Nuclear Density Technician I
HIGHWAY TECHNICIAN CERTIFICATION PROGRAM
I
Course Overview
PREFACE The WisDOT Certified Nuclear Density Technician I course manual was prepared and developed by the Highway Technician Certification Program (HTCP) staff, the HTCP instructors, and other contributors from the Wisconsin Department of Transportation (WisDOT) and the highway industry. The information contained in this course manual is intended to be used to train WisDOT Quality Control/Quality Assurance (QC/QA) Certified Nuclear Density technicians. The intent of this manual is to illustrate the related AASHTO/ASTM test standards and also to discuss the Nuclear Density testing procedures. It is the responsibility of the WisDOT Certified Nuclear Density Technician I to follow all current WisDOT specification parameters and procedures in accordance when conducting work assignments for the Wisconsin Department of Transportation. The WisDOT Certified Nuclear Density Technician I course manual was developed in conjunction with these valuable resources: (1)
Seaman Nuclear Corporation, C-75 and C-200 operator’s manuals, Oak Creek, Wisconsin
(2)
Troxler Electronics Laboratories, Inc., 3400 series and 4640 manuals of operation and instruction, Research Triangle Park, North Carolina
(3)
Troxler Electronics Laboratories, Inc., Troxler Radiation Safety Officer Training Manual, Research Triangle Park, North Carolina
(4)
CPN International, Inc. (Aguinaga Technical Services, Sheboygan, Wisconsin), abbreviated review of the CPN MC Series gauges
ACKNOWLEDGMENTS The Highway Technician Certification Program Nuclear Density Technical committee members have been instrumental contributors to the contents of this course manual. The committee members are: Robert Schiro, WisDOT SE Region John Jorgenson, Mathy Construction Paul Eggen, OMNNI Associates, Inc. Joseph Kyle, American Asphalt Steve Bloedow, Rock Road Companies, Inc. Harry Seaman, Seaman Nuclear Corporation Pat Schroeder, Troxler Electronics Laboratories, Inc. Rich Aguinaga, CPN International David Kopacz, Federal Highway Administration Deb Bischoff, WisDOT, QMP Engineer Jeff Merten WisDOT SW Region, UW-Platteville
WisDOT Technical Assistance Hotline Representative Robert Schiro Mike Bohn
414-750-4153 608-516-6359
Course Overview
Syllabus Day 1 8:00 – 8:15 Registrations, Introductions, Course Objectives and Course Syllabus 8:15 – 8:45 Quality Asphalt Pavements, WisDOT Spec. 8:45 – 9:15 WisDOT 460.3 Hot Mix Asphalt Pavement Construction 9:15 – 10:00 Stone Matrix Asphalt, SMA 10:00 – 10:15 Break 10:15 – 10:30 Rolling and Compaction 10:30 – 11:00 Private Transportation and Storage of Nuclear Density Gauges/Meters 11:00 – 11:30 Troxler Nuclear Density Gauge Operation on Asphaltic Concrete Pavement 11:30 – Noon Seaman Nuclear Density Gauge Operation on Asphaltic Concrete Pavement Noon – 1:00 Lunch Break 1:00 – 3:00 Demonstration of Laboratory Field Testing Procedures 3:00 – 3:15 Break 3:15 – 5:00 Student Practice Laboratory Field Testing Procedures Day 2 8:00 – 9:00 Emergency Procedures for Nuclear Gauge Operators 9:00 – 10:00 Random Sampling Procedures for Asphaltic Concrete Procedures 10:00 – 10:15 Break 10:15 – 11:00 Nuclear Gauge Policy for Operation on WisDOT Projects 11:00 – Noon Correlation/Calibration of Nuclear Density Gauges Noon – 1:00 Lunch Break 1:00 – 5:00 Review, Written Examination, Course Evaluation Adjourn
II
Course Overview
III
Introduction The Highway Technician Certification Program (HTCP) welcomes you to the Certified Nuclear Density Technician I course. This course requires 16 hours of classroom attendance. The course content will cover the Wisconsin Department of Transportation (WisDOT) specification for QMP Asphalt Nuclear Density and operation of nuclear gauges on asphaltic concrete and soils. The student will also become familiar with:
Standardization of nuclear density gauge procedures Nuclear density gauge hands-on, leak testing, and maintenance Random sampling methods Radiation safety practices Calibration/correlation between different nuclear density gauges Trouble-shooting techniques All nuclear density gauges for classes will be provided by WisDOT.
Course Prerequisites All participants should be radiation safety trained by a manufacturer’s nuclear density course or other approved courses by NRC or agreement states. A person may earn 1.6 continuing education units (CEU’s) upon successful completion of this course. Certification Requirements The written examination will be limited to a maximum duration of two (2) hours. The written examination will be “open book and open notes” and will consist of true/false questions, multiple-choice questions, and essay problems. A student will be required to obtain a passing score of 70 percent to be certified as a Nuclear Density Technician I. Recertification Requirements Recertification is mandatory every three (3) years. The HTCP will send a recertification notice to each certified technician and the firm or agency before the expiration date of the highest certification level(s) of certification obtained. The certified technician must apply for recertification before the expiration date of the highest level(s) obtained. Each certified technician is responsible for obtaining his/her recertification.
Course Overview
IV
Revocation/Suspension of Certification Upon written request from any individual, firm, agency, or contractor associated with the HTCP, the HTCP director will provide technical assistance in investigating any alleged report(s) of either certified technician incompetence or act(s) of malfeasance. The HTCP director will then notify WisDOT of the report findings concerning certified technician incompetence or misconduct. Highway Technician Certification Program Goal The principle goal of the Highway Technician Certification Program (HTCP) is to certify that individuals have demonstrated the abilities to engage in quality control/quality assurance activities in highway work contracted by the Wisconsin Department of Transportation (WisDOT). Please visit the Highway Technician Certification Program Website for information about the Assistant Certified Technician-NUC (ACT-NUC)
WELCOME! The HTCP welcomes you to the Certified Nuclear Density Technician I training course. Introduction of Course Participants At this time, you will be asked to introduce yourself, company name, years of service to the Nuclear Density industry, and your present occupational duty. What do you expect from this Training Course? This is your opportunity, as a course participant, to ask the course instructor to cover any other topics related to the Nuclear Density Technician I course. Please list and identify topics below:
Course Overview
V
Duties and Responsibilities of a Certified Nuclear Density Technician I The duties and responsibilities of a Certified Nuclear Density Technician I are:
Know how to perform nuclear sampling and testing and to compute test data results. Know who on the project is responsible for sampling and testing location, frequency, and charting. Know the proper frequency of sampling and testing and be able to sample and test as required by specification. Know how to correlate the nuclear gauge across a secondary standard. Know the safety, handling, and storage requirements for the equipment. Know which project personnel to contact to obtain specification requirements, evaluate the test results in relation to these specifications, and report results to the appropriate persons. Be able to maintain records in an organized manner, and document sampling and testing performed and actions taken as a result of sampling and testing required by specification.
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Course Overview
Glossary of Radiological Terms ALARA:
As Low As Reasonably Achievable
Agreement State:
A state that has signed an agreement with the U.S. Nuclear Regulatory Commission, allowing the state to regulate the use of radioactive materials. Wisconsin is an agreement state and is regulated by the Department of Health Services, Radiation Production Section
Byproduct:
Radioactive material which is a byproduct of a nuclear reactor, such as cesium, americium, radium as of 9-1-07 etc., (regulated and licensed by the NRC or agreement states)
Background Radiation: Compliance Inspection:
Naturally occurring radiation to which we are exposed all the time
An inspection performed by the licensing or registering authority to ensure that leak tests have been performed and that license conditions are being followed
Dose:
The radiation absorbed by the body
Dosimeter:
A personal measuring device used to monitor one=s radiation exposure. Examples are film badge or TLD
Half-life:
Time for radioactivity to decay to one half of the original value Some examples for some well-known radioisotopes: - radium: 1620 years - cesium: 30 years - americium: 450 years - radon: 3.8 days - uranium: 4,490,000,000 years
Ionizing Radiation:
The result of the change of an atom’s nucleus
Leak Tests:
Tests performed on nuclear meters to ensure the integrity of the source capsule
Man-Made Radiation:
The radioactive substances or sources of radiation created by man (e.g., medical x-rays, byproduct materials)
NARM:
Naturally occurring or Accelerator produced Radioactive Material, such as uranium, radium, etc. (licensed by NRC or an agreement state)
Non-Agreement State:
A state in which an NRC license is required for possession of byproduct material and for manmade radioactive material and for
VII
Course Overview naturally occurring radioactive material such as radium 226. Radioisotope:
A radioactive form of an element, either man-made or naturally-occurring
NRC:
U.S. Nuclear Regulatory Commission, the regulatory body responsible for ensuring the safety and security of nuclear products and facilities
(Radio)activity:
Rate of radioactive decay Two units of measure are commonly used: Curie: (Ci) is the activity of 1 g radium (37 billion decays/sec.) Becquerel: (Bq) is the amount of radioactive material that Undergoes one decay/sec.
Roentgen:
Quantity of ionizing radiation, the level of radioactivity is usually expressed in R/hr, or mr/hr.
RAD:
(Radiation Absorbed Dose) quantity of radiation received
REM:
(Radiation Equivalent Man) the traditional unit measuring the radiation dose equivalent or biological effect on living tissue. This quantity will depend on the type (alpha, gamma, etc.) as well as the amount of radiation received. This unit is used for protection and administration purposes.
RBE:
(Relative Biological Effectiveness) used to determine the equivalent dose, in REM or sievert (it depends on type of radiation)
RPO:
Radiation Protection Officer
RSO:
Radiation Safety Officer
Sealed Source:
Radioactive material encased in two protective capsules
Sievert:
System International (SI) unit of radiation dose absorbed equivalent, equal to 100 REM
Shipping Papers:
Information carried by the driver of a vehicle which identifies the nature and classification of a radioactive shipment
Unrestricted Area:
An area to which access is not restricted and where warning signs are not required, and the general public can not receive 2 mrems an hour or 100 per year.
VIII
Course Overview
General Glossary FC
Face of curb
Transit line
Offset
Stationing:
In route surveying, a system called stationing is used to specify the relative position of any point along the reference line. The starting point is usually designated with some arbitrary value, for example, 10+00 or 100+00, although 0+00 can be used. If the beginning point was 10+00, the first stake 100ft along the line from it would be designated 11+00, the one 200 ft along the line 12+00 and so on. The term full station is applied to each of these points set at 100-ft increments. A point located between two full stations, say 84 ft beyond station 17+00, would be designated 17+84. Thus locations of intermediate points are specified by their nearest preceding full station and their plus. In the designation of station 17+84, the plus is 84. In rugged areas, and in urban situations, half-stations with a plus of 50 ft are often also staked. Even quarter-stations (at 25-ft increments) are sometimes placed in these situations. Stationing not only provides a convenient unambiguous method for specifying positions of points along the reference line, it also gives the distances between points. For example, station 24+18 and 17+84.9 are (2418 – 1784) or 634 ft, apart. Elementary Surveying, 9th Edition, Wolf and Brinker
Assume the above roadway is 12’ wide and 1000’ long. Label the above roadway assuming the starting point is 10+00.. Plot the point at station 7+84, with a 3 ft offset.
IX
Course Overview
Table of Contents Course Overview A. Quality Asphaltic Pavement ....................................................................................... A-1 B. WisDOT Quality Management Program Specifications .............................................. B-1 C. WisDOT 460.3 Hot Mix Asphalt Pavement Construction ........................................... C-1 D. Stone Matrix Asphalt, SMA ........................................................................................ D-1 E. Soils .............................................................................................................................. E-1 F. Private Transportation and Storage............................................................................. F-1 G. Troxler, Humboldt, and CPN Nuclear Gauge Operation and Procedures .................. G-1 H. Seaman Gauge Nuclear Operation and Procedures .................................................. H-1 I. Emergency Procedures for Nuclear Density Gauges .....................................................I-1 J. Random Sampling Procedures ..................................................................................... J-1 K. Nuclear Gauge Policy for Operation on WisDOT Projects ...........................................K-1 L. Nuclear Density Worksheets ........................................................................................ L-1
Appendix 1, CMM 8.15, AASHTO Test Numbers, Lab Exam .................................... Appdx-1 Appendix 2, QMP Award, Corrections, Course Evaluation ..................................... Appdx-2
Topic A: Quality Asphaltic Pavement
Topic A: Quality Asphaltic Pavement
A-1
A. Quality Asphaltic Pavement Quality Hot Mix Asphalt
Factors Related to Durability Sufficient Asphalt Binder in Mixture Sufficient Compactive Effort Sufficient Air Voids Quality of Aggregate
The durability of an asphaltic concrete pavement is attributed to: Sufficient asphalt binder in the hot-mix asphalt (HMA) mixture is necessary to provide an adequate asphalt film thickness around the aggregate particles to minimize asphalt binder hardening or aging during asphaltic mix production. Sufficient compactive effort and air voids are directly related, to the compactive effort (density) must be closely monitored to control and achieve the specified percent air voids for the specified HMA mix type. At this time, the amount of air voids measured in the HMA mixture is the most important factor in predicting HMA pavement performance. Historical data indicates air voids between 2 and 4 percent are recommended for optimum pavement performance. The WisDOT HMA density specifications require the HMA mixture to be placed and compacted with at least 7 percent air voids, this depends on the specified type of asphaltic mixture. In theory, within a two to three year period of additional traffic loading the HMA pavement will further density to the recommended measured air void performance level of between 2 and 4 percent. Optimum HMA Performance Air voids between 2 and 4 percent after two to three years of further traffic densification will provide optimum asphaltic concrete pavement performance.
For quality HMA pavement, the density value is entered into the Nuclear Density Gauge. This value is derived from the mix design’s theoretical maximum specific gravity (Gmm) for the first day’s placement. The running average is used from that point on for that mix design.
Topic A: Quality Asphaltic Pavement
A-2
Compaction of Asphalt Pavement (continued) The compaction of HMA pavement is accomplished through the use of breakdown and intermediate rollers to achieve the specified density and a finish roller to remove all the roller marks. If the breakdown roller can achieve the specified density then an intermediate roller may not be necessary. Percent compaction is accomplished by taking the mix design theoretical maximum specific gravity (Gmm) or the running average number specific gravity (Gmm) times (x) 62.24. This number is what needs to be entered into your moisture / density gauge. It gives you the lab density required for figuring out percent compaction.
Types of Compaction Equipment for Asphaltic Concrete Smooth Steel-Wheeled Rollers Smooth Three Steel-Wheeled Rollers Pneumatic Tired Rollers
Two types of compactors used to densify HMA mixtures are: 1) smooth steel-wheeled rollers and 2) pneumatic tired roller.
The smooth steel-wheeled roller can be either static or vibratory. Static rollers compact using only the weight of the roller. Vibratory rollers have one, two, or three steel drums with rotating weights. These weights vibrate these drums creating a dynamic force, which is added to the static rolling force. The pneumatic tired rollers are static rollers. Pneumatic tired rollers allow adjustment by varying the tire pressure.
Topic A: Quality Asphaltic Pavement General Principles on When to Use Vibration on Double Drum Vibrators •Use both drums in static on 1 inch mat or less. •Use lead drum when vibrating on mat 2 inches or less. •Use both drums when vibrating on mat 2 inches or greater.
A-3
Topic B: Quality Management Program Hot Mix Asphalt Pavement Nuclear Density
QMP HMA Pavement Nuclear Density. A Description Replace standard spec 460.3.3.2 (1) and 460.3.3.2 (4) with the following: (1)
(2)
(3)
(4)
This special provision describes density testing of in-place HMA pavement with the use of nuclear density gauges. Conform to standard spec 460 as modified in this special provision. Provide and maintain a quality control program defined as all activities and documentation of the following: 1. Selection of test sites. 2. Testing. 3. Necessary adjustments in the process. 4. Process control inspection. Chapter 8 of the department’s construction and materials manual (CMM) provides additional detailed guidance for QMP work and describes required procedures. Obtain the CMM from the department’s web site at: http://roadwaystandards.dot.wi.gov/standards/cmm/index.htm The department’s Materials Reporting System (MRS) software allows contractors to submit data to the department electronically, estimate pay adjustments, and print selected reports. Qualified personnel may obtain MRS software from the department’s web site at: http://www.atwoodsystems.com/mrs
B Materials B.1 Personnel (1) Perform HMA pavement density (QC, QV) testing using a HTCP certified nuclear technician I, or a nuclear assistant certified technician (ACT-NUC) working under a certified technician. (2)
If an ACT is performing sampling or testing, a certified technician must coordinate and take responsibility for the work an ACT performs. Have a certified technician ensure that all sampling and testing is performed correctly, analyze test results, and post resulting data. No more than one ACT can work under a single certified technician.
B.2 Testing (1) Conform to ASTM D2950 and CMM 8.15 for density testing and gauge monitoring methods. Perform nuclear gauge measurements using gamma radiation in the backscatter position. Perform each test for 4 minutes of nuclear gauge count time. B.3 Equipment B.3.1 General 1 of 8
(1)
(2)
(3)
Furnish nuclear gauges from the department’s approved product list at http://www.dot.wisconsin.gov/business/engrserv/approvedprod.htm. Have the gauge calibrated by the manufacturer or an approved calibration service within 12 months of its use on the project. Retain a copy of the manufacturer’s calibration certificate with the gauge. Prior to each construction season, and following any calibration of the gauge, the contractor must perform calibration verification for each gauge using the reference blocks located in the department’s central office materials laboratory. To obtain information or schedule a time to perform calibration verification, contact the department’s Radiation Safety Officer at: Materials Management Section 3502 Kinsman Blvd. Madison, Wisconsin 53704 Telephone: 608-243-5998
B.3.2 Comparison of Nuclear Gauges B.3.2.1 Comparison of QC and QV Nuclear Gauges (1) Select a representative section of the compacted pavement prior to or on the first day of paving for the comparison process. The section does not have to be the same mix design. (2)
Compare the 2 or more gauges used for density measurement (QC, QV). The QC and QV gauge operators will perform the comparison on 5 test sites jointly located. Record each density measurement of each test site for the QC, QV and back up gauges.
(3)
Calculate the average of the difference in density of the 5 test sites between the QC and QV gauges. Locate an additional 5 test sites if the average difference exceeds 1.0 lb/ft3. Measure and record the density on the 5 additional test sites for each gauge.
(4)
Calculate the average of the difference in density of the 10 test sites between the QC and QV gauges. Replace one or both gauges if the average difference of the 10 tests exceeds 1.0 lb/ft3 and repeat comparison process from B.3.2.1 (2).
(5)
Furnish one of the QC gauges passing the allowable correlation tolerances to perform density testing on the project. B.3.2.2 Comparison Monitoring (1) After performing the gauge comparison specified in B.3.2.1, establish a project reference site approved by the department. Clearly mark a flat surface of concrete or asphalt or other material that will not be disturbed during the duration of the project. Perform comparison monitoring of the QC, QV, and all back-up gauges at the project reference site.
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(2)
(3)
(4)
Conduct an initial 10 density tests with each gauge on the project reference site and calculate the average value for each gauge to establish the gauge’s reference value. Use the gauge’s reference value as a control to monitor the calibration of the gauge for the duration of the project. Check each gauge on the project reference site a minimum of one test per day if paving on the project. Calculate the difference between the gauge’s daily test result and its reference value. Investigate if a daily test result is not within 1.5 lb/ft3 of its reference value. Conduct 5 additional tests at the reference site once the cause of deviation is corrected. Calculate and record the average of the 5 additional tests. Remove the gauge from the project if the 5-test average is not within 1.5 lb/ft3 of its reference value established in B.3.2.2(2). Maintain the reference site test data for each gauge at an agreed location.
B.4 Quality Control Testing and Documentation B.4.1 Lot and Sublot Requirements B.4.1.1 Mainline Traffic Lanes, Shoulders, and Appurtenances (1) A lot consists of the tonnage placed each day for each layer and target density specified in standard spec 460.3.3.1. A lot may include partial sublots. (2)
(3)
(4)
(5)
(6)
Divide the roadway into sublots. A sublot is 1500 lane feet for each layer and target density. A sublot may include HMA placed on more than one day of paving. Test sublots at the pre-determined random locations regardless of when the HMA is placed. No additional testing is required for partial sublots at the beginning or end of a day’s paving. If a resulting partial quantity at the end of the project is less than 750 lane feet, include that partial quantity with the last full sublot of the lane. If a resulting partial quantity at the end of the project is 750 lane feet or more, create a separate sublot for that partial quantity. Randomly select test locations for each sublot as specified in CMM 8.15 prior to paving and provide a copy to the engineer. Locate and mark QC density test sites when performing the tests. Perform density tests prior to opening the roadway to traffic. Use Table 1 to determine the number of tests required at each station, depending on the width of the lane being tested. When more than one test is required at a station, offset the tests 10 feet longitudinally from one another to form a diagonal testing row across the lane. Lane Width No. of Tests Transverse Location 5 ft or less 1 Random Greater than 5 ft to 9 ft 2 Random within 2 equal widths
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Greater than 9 ft
3
Random within 3 equal widths Table 1
B.4.1.2 Side Roads, Crossovers, Turn Lanes, Ramps, and Roundabouts (1) A lot represents a combination of the total daily tonnage for each layer and target density. (2)
(3)
(4)
Each side road, crossover, turn lane, ramp, and roundabout must contain at least one sublot for each layer. If a side road, crossover, turn lane, or ramp is 1500 feet or longer, determine sublots and random test locations as specified in B.4.1.1. If a side road, crossover, turn lane, or ramp is less than 1500 feet long, determine sublots using a maximum of 750 tons per sublot and perform the number of random tests as specified in Table 2. Side Roads, Turn Lanes, Crossovers, Ramps, Minimum Number Roundabouts: Sublot/Layer tonnage of Tests Required 25 to 100 tons 1 101 to 250 tons 3 251 to 500 tons 5 501 to 750 tons 7 Table 2
B.4.2 Pavement Density Determination B.4.2.1 Mainline Traffic Lanes and Appurtenances (1) Calculate the average sublot densities using the individual test results in each sublot. (2)
(3)
If all sublot averages are no more than one percent below the target density, calculate the daily lot density by averaging the results of each random QC test taken on that day’s material. If any sublot average is more than one percent below the target density, do not include the individual test results from that sublot when computing the lot average density and remove that sublot’s tonnage from the daily quantity for incentive. The tonnage from any such sublot is subject to disincentive pay according to standard spec 460.5.2.2.
B.4.2.2 Mainline Shoulders B.4.2.2.1 Width Greater Than 5 Feet (1) Determine the pavement density as specified in B.4.2.1. B.4.2.2.2 Width of 5 Feet or Less (1) If all sublot test results are no more than 3.0 percent below the minimum target density, calculate the daily lot density by averaging all individual test results for the day.
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(2)
If a sublot test result is more than 3.0 percent below the target density, the engineer may require the unacceptable material to be removed and replaced with acceptable material or allow the nonconforming material to remain in place with a 50 percent pay reduction. Determine the limits of the unacceptable material according to B.4.3.
B.4.2.3 Side Roads, Crossovers, Turn Lanes, Ramps, and Roundabouts (1) Determine the pavement density as specified in B.4.2.1. B.4.2.4 Documentation (1) Document QC density test data as specified in CMM 8.15. Provide the engineer with the data for each lot within 24 hours of completing the QC testing for the lot. B.4.3 Corrective Action (1) Notify the engineer immediately when an individual test is more than 3.0 percent below the specified minimum in standard spec 460.3.3.1. Investigate and determine the cause of the unacceptable test result. (2)
(3)
(4)
(5)
(6)
The engineer may require unacceptable material specified in B.4.3(1) to be removed and replaced with acceptable material or allow the nonconforming material to remain in place with a 50 percent pay reduction. Determine limits of the unacceptable area by measuring density of the layer at 50-foot increments both ahead and behind the point of unacceptable density and at the same offset as the original test site. Continue testing at 50-foot increments until a point of acceptable density is found as specified in standard spec 460.5.2.2(1). Removal and replacement of material may be required if extended testing is in a previously accepted sublot. Testing in a previously accepted sublot will not be used to recalculate a new lot density. Compute unacceptable pavement area using the product of the longitudinal limits of the unacceptable density and the full sublot width within the traffic lanes or shoulders. Retesting and acceptance of replaced pavement will be according to standard spec 105.3. Tests indicating density more than 3.0 percent below the specified minimum, and further tests taken to determine the limits of unacceptable area, are excluded from the computations of the sublot and lot densities. If 2 consecutive sublot averages within the same paving pass and same target density are more than one percent below the specified target density, notify the engineer and take necessary corrective action. Document the locations of such sublots and the corrective action that was taken.
B.5 Department Testing B.5.1 Verification Testing
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(1)
(2)
(3)
(4)
(5)
(6)
The department will have a HTCP certified technician, or ACT working under a certified technician, perform verification testing. The department will test randomly at locations independent of the contractor’s QC work. The department will perform verification testing at a minimum frequency of 10 percent of the sublots and a minimum of one sublot per mix design. The sublots selected will be within the active work zone. The contractor will supply the necessary traffic control for the department’s testing activities. The QV tester will test each selected sublot using the same testing requirements and frequencies as the QC tester. If the verification sublot average is not more than one percent below the specified minimum target density, use the QC tests for acceptance. If the verification sublot average is more than one percent below the specified target density, compare the QC and QV sublot averages. If the QV sublot average is within 1.0 lb/ft3 of the QC sublot average, use the QC tests for acceptance. If the first QV/QC sublot average comparison shows a difference of more than 1.0 lb/ft3 each tester will perform an additional set of tests within that sublot. Combine the additional tests with the original set of tests to compute a new sublot average for each tester. If the new QV and QC sublot averages compare to within 1.0 lb/ft3, use the original QC tests for acceptance. If the QV and QC sublot averages differ by more than 1.0 lb/ft3 after a second set of tests, resolve the difference with dispute resolution specified in B.6. The engineer will notify the contractor immediately when density deficiencies or testing precision exceeding the allowable differences are observed.
B.5.2 Independent Assurance Testing (1) Independent assurance is unbiased testing the department performs to evaluate the department’s verification and the contractor’s QC sampling and testing including personnel qualifications, procedures, and equipment. The department will perform the independent assurance review according to the department’s independent assurance program. B.6 Dispute Resolution (1) The testers may perform investigation in the work zone by analyzing the testing, calculation, and documentation procedures. The testers may perform gauge comparison according to B.3.2.1. (2)
The testers may use comparison monitoring according to B.3.2.2 to determine if one of the gauges is out of tolerance. If a gauge is found to be out of tolerance with its reference value, remove the gauge from the project and use the other gauge’s test results for acceptance.
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(3)
(4)
If the testing discrepancy cannot be identified, the contractor may elect to accept the QV sublot density test results or retesting of the sublot in dispute within 48 hours of paving. Traffic control costs will be split between the department and the contractor. If investigation finds that both gauges are in error, the contractor and engineer will reach a decision on resolution through mutual agreement.
B.7 Acceptance (1) The department will not accept QMP HMA Pavement Nuclear Density if a noncompared gauge is used for contractor QC tests. C (Vacant) D (Vacant) E Payment E.1 QMP Testing (1) Costs for all sampling, testing, and documentation required under this special provision are incidental to the work. If the contractor fails to perform the work required under this special provision, the department may reduce the contractor’s pay. The department will administer pay reduction under the Non-performance of QMP administrative item. E.2 Disincentive for HMA Pavement Density (1) The department will administer density disincentives according to standard spec 460.5.2.2. E.3 Incentive for HMA Pavement Density (1) Delete standard spec 460.5.2.3. (2)
If the lot density is greater than the minimum specified in standard spec table 460-3 and all individual air voids test results for that mixture are within +2.5% to 4.0%, the department will adjust pay for that lot as follows: Percent Lot Density Above Minimum From -0.4 to 1.0 inclusive From 1.1 to 1.8 inclusive More than 1.8
(3)
(4)
Pay Adjustment Per Ton $0 $0.40 $0.80
The department will adjust pay under the Incentive Density HMA Pavement bid item. Adjustment under this item is not limited, either up or down, to the bid amount shown on the schedule of items. If a traffic lane meets the requirements for disincentive, the department will not pay incentive on the integrally paved shoulder.
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Submit density results to the department electronically using the MRS software. The department will validate all contractor data before determining pay adjustments. 460-020 (20100709) (5)
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Topic C: WisDOT 460.3 Hot Mix Asphalt Pavement Construction
- Va is within a range of 2.7 to 5.3 percent. - VMA is within minus 0.5 of the minimum requirement for the mix design nominal maximum aggregate size. (2)
(3)
(1)
TR AC T
(1)
AD
M
IN
(2)
AT I
(3)
IS TR
(2)
O
N
(1)
If QV test results are outside the specified limits, the engineer will investigate immediately through dispute resolution procedures. The engineer may stop production while the investigation is in progress if the potential for a pavement failure is present. If production continues for that mixture design, the engineer will provide additional retained sample testing at the frequency provided for in CMM 8-36. This supplemental testing will continue until the material meets allowable differences or as the engineer and contractor mutually agree. 460.2.8.3.1.7 Dispute Resolution When QV test results do not meet the specified limits, the bureau's AASHTO accredited laboratory and certified personnel will referee test the retained portion of the QV sample and the retained portion of the nearest available previous QC sample. The department will notify the contractor of the referee test results within 3 business days after receipt of the samples. The department will determine mixture conformance and acceptability by analyzing referee test results, reviewing mixture project data, and inspecting the completed pavement all according to CMM 8-36. 460.2.8.3.1.8 Corrective Action Remove and replace unacceptable material at no additional expense to the department. The department will reduce pay for the tonnage of nonconforming mixture, as determined during QV dispute resolution, if the engineer allows that mixture to remain in place. If production of that mixture design continued during the investigation, the department will also adjust pay for that mixture forward to the next conforming QV or QC point. The department will pay for the affected mixture as specified in 460.5.2.1. 460.2.8.3.2 Independent Assurance Testing The department will evaluate both the contractor and department testing personnel and equipment as specified in 106.3.4.3.4. 460.3 Construction 460.3.1 General
Revise 460.3.1 to specify the encoding for the combined bid item naming convention. (1)
Construct HMA pavement of the type the bid item indicates encoded as follows:
C O
N
Combined Bid Item Encoding
1
TRAFFIC VOLUME
BINDER DESIGNATION LEVEL
37.5 mm
LT
Low
S
Standard
25.0 mm
MT
Medium
H
Heavy
3
19.0 mm
HT
High
V
Very Heavy
4
12.5 mm
E
Extremely Heavy
T
FO
2
R
GRADATIONS (NMAS)
O
5
4.75 mm
N
6
9.5 mm
(2)
Construct HMA pavement conforming to the general provisions of 450.3. 460.3.2 Thickness
Revise 460.3.2(1) to include gradation numbers and update the minimum and maximum required thickness. (1)
Provide the plan thickness for lower and upper layers limited as follows:
Effective with the December 2016 Letting
184
2017 Standard Specifications
MINIMUM LAYER MAXIMUM LOWER MAXIMUM UPPER MAXIMUM SINGLE THICKNESS LAYER THICKNESS LAYER THICKNESS LAYER THICKNESS[3] in inches in inches in inches in inches No. 1 (37.5 mm) 4.5 6 4.5 6 No. 2 (25.0 mm) 3.0 5 4 6 No. 3 (19.0 mm 2.25 4 3 5 1.75 3[2] 2.5 4 No. 4 (12.5 mm)[1] [4] [1] [4] [2] No. 5 (9.5 mm) 1.5 3 2 3 [1] SMA mixtures use nominal size No. 4 (12.5 mm) or No. 5 (9.5 mm). [2] SMA mixtures with nominal sizes of No. 4 (12.5 mm) and No. 5 (9.5 mm) have no maximum lower layer thickness specified. [3] For use on cross-overs and shoulders. [4] Can be used for a leveling layer or scratch coat at a reduced thickness.
AT I
O N
NOMINAL SIZE
460.3.3 HMA Pavement Density Maximum Density Method 460.3.3.1 Minimum Required Density
Compact all layers of HMA mixture to the density table 460-3 shows for the applicable mixture, location, and layer.
IN IS
(1)
TR
Revise 460.3.3.1(1) table 460-3 to switch from E mixes to LT, MT, and HT mixes. This revision incorporates STSP460-025.
TABLE 460-3 MINIMUM REQUIRED DENSITY[1]
PERCENT OF TARGET MAXIMUM DENSITY LAYER
MIXTURE TYPE SMA[5]
91.5[3]
92.0[4]
___
UPPER
91.5
92.0
___
92.0[4]
___
91.5
92.0
___
[3]
LOWER
SHOULDERS & APPURTENANCES
LOWER
89.5
89.5
___
UPPER
90.5
90.5
___
[4]
[5]
TR
N
C O
R
[3]
The table values are for average lot density. If any individual density test result falls more than 3.0 percent below the minimum required target maximum density, the engineer may investigate the acceptability of that material. Includes parking lanes as determined by the engineer. Minimum reduced by 2.0 percent for a lower layer constructed directly on crushed aggregate or recycled base courses. Minimum reduced by 1.0 percent for a lower layer constructed directly on crushed aggregate or recycled base courses. The minimum required densities for SMA mixtures are determined according to CMM 8-15.
FO
[2]
UPPER
91.5
AC
SIDE ROADS, CROSSOVERS, TURN LANES, & RAMPS
[1]
T
460.3.3.2 Pavement Density Determination The engineer will determine the target maximum density using department procedures described in CMM 8-15. The engineer will determine density as soon as practicable after compaction and before placement of subsequent layers or before opening to traffic. Do not re-roll compacted mixtures with deficient density test results. Do not operate continuously below the specified minimum density. Stop production, identify the source of the problem, and make corrections to produce work meeting the specification requirements. A lot is defined in CMM 8-15 and placed within a single layer for each location and target maximum density category indicated in table 460-3. The lot density is the average of all samples taken for that lot. The department determines the number of tests per lot according to either the linear sublot system or the nominal tonnage system defined in CMM 8-15. A certified nuclear density technician, or a nuclear density ACT working under a certified nuclear density technician, will locate samples and perform the testing. A certified nuclear density technician must coordinate and take responsibility for the work an ACT performs. No more than one ACT can work under
N
O
(1)
HT
LOWER
T
TRAFFIC LANES[2]
AD
LT and MT
M
LOCATION
(2)
(3)
(4)
Effective with the December 2016 Letting
185
2017 Standard Specifications
(1)
a single certified technician. The responsible certified technician will ensure that sample location and testing is performed correctly, analyze test results, and provide density results to the contractor weekly. 460.3.3.3 Waiving Density Testing The engineer may waive density testing for one or more of the following reasons: 1. It is impracticable to determine density by the lot system. 2. The contract contains less than 750 tons of a given mixture type placed within the same layer and target maximum density category.
(3)
AT I
(1)
If the department waives density testing notify the contractor before paving. The department will accept the mixture by the ordinary compaction procedure as specified in 450.3.2.6.2. If HMA QC testing is waived under 460.2.8.2.1.3.3, density testing is also waived. 460.4 Measurement The department will measure the HMA Pavement bid items acceptably completed by the ton as specified in 450.4. 460.5 Payment 460.5.1 General
O N
(2)
IN IS
The department will pay for measured quantities at the contract unit price under the following bid items: DESCRIPTION HMA Pavement (gradation) LT (binder)(designation) HMA Pavement (gradation) MT (binder)(designation) HMA Pavement (gradation) HT (binder)(designation) HMA Pavement (gradation) SMA (binder)(designation) Incentive Density HMA Pavement
M
ITEM NUMBER 460.5000 - 5999 460.6000 - 6999 460.7000 - 7999 460.8000 - 8999 460.2000
AD
(1)
TR
Revise 460.5.1(1) to add combined bid items that specify the gradation, traffic, binder, and designation. This revision incorporates STSP460-025.
T
460.5.2 HMA Pavement 460.5.2.1 General
UNIT TON TON TON TON DOL
O
T
(4)
R
(3)
Payment for the HMA Pavement bid items is full compensation for providing HMA pavement including binder; for mixture design; for preparing the foundation; and for QMP and aggregate source testing. If provided for in the plan quantities, the department will pay for a leveling layer, placed to correct irregularities in an existing paved surface before overlaying, under the pertinent paving bid item. Absent a plan quantity, the department will pay for a leveling layer as extra work. The department will administer pay reduction for nonconforming QMP mixture under the Nonconforming QMP HMA Mixture administrative item. The department will reduce pay based on the contract unit price for the HMA Pavement bid item. The department will reduce pay for nonconforming QMP HMA mixtures as specified in 460.2.8.2.1.7, starting from the stop point to the point when the running average of 4 is back inside the warning limits. The engineer will determine the quantity of material subject to pay reduction based on the testing data and an inspection of the completed pavement. The department will reduce pay as follows:
FO
(2)
Disincentive for density of HMA pavement as specified in 460.5.2.2. Incentive for density of HMA pavement as specified in 460.5.2.3. Reduced payment for nonconforming smoothness as specified in 450.3.2.9. Reduced payment for nonconforming QMP HMA mixtures as specified in 460.2.8.2.1.7.
N
1. 2. 3. 4.
TR
The department will pay for the HMA Pavement bid items at the contract unit price subject to one or more of the following adjustments:
C O
(1)
AC
Revise 460.5.2.1 to specify nonconforming combined bid item pay adjustments. This revision incorporates STSP460-025.
N
(5)
Effective with the December 2016 Letting
186
2017 Standard Specifications
[2]
(8)
TR
AD
(1)
IN IS
(7)
If the department discovers nonconforming mixture during a QV dispute resolution investigation, and the engineer allows that mixture to remain in place, the department will pay for the quantity of affected material as specified in 460.2.8.3.1.8 at 50 percent of the contract price. If the department waives density testing under 460.3.3.3, the department will not adjust pay under either 460.5.2.2 or 460.5.2.3. Restore the surface after cutting density samples as specified in 460.3.3.2(1) at no additional cost to the department. 460.5.2.2 Disincentive for HMA Pavement Density The department will administer density disincentives under the Disincentive Density HMA Pavement administrative item. If the lot density is less than the specified minimum in table 460-3, the department will reduce pay based on the contract unit price for the HMA Pavement bid item for that lot as follows:
M
(6)
AT I
[3]
O N
[1]
PAYMENT FOR MIXTURE[1] [2] PRODUCED WITHIN PRODUCED OUTSIDE ITEM WARNING BANDS JMF LIMITS Gradation 90% 75% Asphalt Content 85% 75% Air Voids 70% 50% VMA 90% 75% For projects or plants where the total production of each mixture design requires less than 4 tests refer to CMM 8-36. Payment is in percent of the contract unit price for the HMA Pavement bid item. The department will reduce pay based on the nonconforming property with lowest percent pay. In addition to any pay adjustment listed in the table above, the department will adjust pay for nonconforming binder under the Nonconforming QMP Asphaltic Material administrative item. The department will deduct 25 percent of the contract unit price of the HMA Pavement bid item per ton of pavement placed with nonconforming PG binder the engineer allows to remain in place.
FO
N
O
(1)
The department will not assess density disincentives for pavement placed in cold weather because of a department-caused delay as specified in 450.5.2(3). 460.5.2.3 Incentive for HMA Pavement Density If the lot density is greater than the minimum specified in table 460-3 and all individual air voids test results for that mixture placed during the same day are within +1.0 percent or - 0.5 percent of the design target in table 460-2, the department will adjust pay for that lot as follows:
T
(2)
R
[1]
C O
N
TR
AC
T
DISINCENTIVE PAY REDUCTION FOR HMA PAVEMENT DENSITY PERCENT LOT DENSITY PAYMENT FACTOR BELOW SPECIFIED MINIMUM (percent of contract price) From 0.5 to 1.0 inclusive 98 From 1.1 to 1.5 inclusive 95 From 1.6 to 2.0 inclusive 91 From 2.1 to 2.5 inclusive 85 From 2.6 to 3.0 inclusive 70 [1] ___ More than 3.0 Remove and replace the lot with a mixture at the specified density. When acceptably replaced, the department will pay for the replaced work at the contract unit price. Alternatively the engineer may allow the nonconforming material to remain in place with a 50 percent payment factor.
INCENTIVE PAY ADJUSTMENT FOR HMA PAVEMENT DENSITY PERCENT LOT DENSITY ABOVE SPECIFIED MINIMUM PAY ADJUSTMENT PER TON[1] From -0.4 to 1.0 inclusive $0 From 1.1 to 1.8 inclusive $0.40 More than 1.8 $0.80 [1] The department will prorate the pay adjustment for a partial lot.
(2)
(3)
The department will adjust pay under the Incentive Density HMA Pavement bid item. Adjustment under this item is not limited, either up or down, to the bid amount the schedule of items shows. The department will restrict incentive payment for shoulders paved integrally with the traffic lane, if the traffic lane does not meet incentive requirements, the department will not pay incentive on the integrally paved shoulder.
Effective with the December 2016 Letting
187
2017 Standard Specifications
Topic D: Stone Matrix Asphalt, SMA
Construction and Materials Manual Chapter 8 Section 15
Wisconsin Department of Transportation
Materials Testing, Sampling, Acceptance Density Testing
Materials sampling and testing methods and documentation procedures prescribed in chapter 8 of the CMM are mobilized into the contract per standard spec 106.3.4.1 and standard spec 106.3.4.3.1. CMM provisions mobilized by the contract: CMM 8-15.10.2.1, CMM 8-15.10.2.2, CMM 8-15.10.2.3
8-15.13 Density Testing Requirements for Stone Matrix Asphalt (SMA) and Coarse (Gap-graded) mixes The procedure for determing compactive effort to stablize the SMA and gap graded mixes prescribed in CMM 8-15.13.1 is mobilized into the contract per standard spec 460.3.3.2.
8-15.13.1 Density Testing SMA & Gap Graded Mixes Density determination procedures and requirements for Stone Matrix Asphalt (SMA) pavements and coarse, gap graded mixes are different from other HMA pavements. The following procedure must be used to determine the compactive effort needed to stabilize the SMA and gap graded mixes. Gap-graded mixtures have gradations when plotted on a 0.45 power graph cross the maximum density line from the fine side to the coarse at or before the No. 8 sieve and are predominately on the low side (at or below the minimum allowable in Table 460-1) of the allowable passing for the sieve sizes that plot on the coarse side of the maximum density curve. Since SMA is a type of gap-graded mixture, only the term SMA will be used in the following to describe both SMA and gap- graded mixtures. See Figure 5- SMA (Gap-Graded) Gradations. Figure 5 SMA(Gap Graded) Gradations
Determine compactive effort for SMA pavement using the control strip method. Construct a control strip at the beginning of work for each layer of SMA to be compacted. Ensure that the control strip, when acceptably compacted and meeting finish and smoothness requirements, remains in place and becomes part of the completed pavement. Ensure that the SMA mixture is composed of the same material with the same mixture design as the rest of the layer. The initial placement of the first 1500 feet of SMA will be accepted by ordinary compaction 450.3.2.6.2. After the May 2015
Page 1
CMM 8-15 Density Testing
placement of the initial 1500 feet of SMA pavement, density will be determined by the control strip method as follows. The control strip shall consist of 1,000 feet of the SMA mixture that contains a minimum of one mixture QC test and twelve sites for nuclear density testing. Within the control strip, the Department, using random numbers for stationing, will determine twelve locations for density testing. Upon completion of the desired compaction for the control strip, the contractor will perform nuclear density tests at the twelve locations. Do not use additional materials to aid in seating the gauge. Determine the control strip target density by calculating the median value of the random twelve nuclear density locations. Within 24 hours, provide the department with test results for the mixture QC sample and control strip target density. Use the control strip target density as the target compactive effort for remaining layer acceptance if the air voids from the mixture QC sample taken during control strip construction falls between 3.5% and 5.0%. If the test results do not meet these minimum requirements, an investigation will result and a new control test strip may be required. Acceptance of the remaining layer will be determined by standard department procedures using the control strip median density, recorded as a percentage of the target density. Stop mixture production and initiate an investigation if any of the following conditions occur: 1. There is a change in mix design (i.e. new 250 number); 2. The previous day's maximum specific gravity average from QC testing, varies by ≥0.020 from the value from the initial QC test; 3. The overall blend changes have deviated from the original mix design by ≥ 10%; 4. There is a change in the average lot density in two sequential lots either below or above control strip target density by 2.0% (in PCF) inclusive 5. Any other condition occurs which in the judgment of the project engineer would warrant the establishment of a new control strip density
Note: for shoulders paved integrally with mainline pavement, but over different base/subgrade materials, determine and test at another twelve randomly located test spots in the shoulder area. Determine the shoulder control strip target density by calculating the median value of the random twelve nuclear density locations. Example of determining median target density: Sort the 12 measured densities into numerical order. For this example the densities are sorted from the lowest to highest value.
Submit the results to the project engineer. QMP Nuclear Density testing applies for SMA as it would normally apply for mainline paving greater than 10,000 Tons. The Materials Reporting system is not designed to accept nuclear density test results for SMA. SMA is not subject to density incentive/disincentive bid items. Also note that the control strip is not to be used for gauge correlation. That procedure is to be done as described in CMM 815.7 and will be completed before density testing in the control strip. The 12 density tests required for determining the control strip density and rolling pattern for asphalt base, prescribed in CMM 8-15.13.2 is mobilized into the contract per standard spec 460.3.3.2.
8-15.13.2 Density Testing Asphaltic Base Mixtures The control strip shall consist of 1000 feet of the asphaltic base mixture that contains a minimum of one QC mixture test and twelve sites for nuclear density testing. Within the control strip, the department, using random numbers for sample determination, will identify twelve locations for density testing. Upon completion of the May 2015
Page 2
CMM 8-15 Density Testing
desired compaction for the control strip, nuclear density tests will be performed by the contractor at the twelve locations. Do not use additional materials to aid in seating the gauge. The Control Strip accepted density will be determined by calculating the median value of the random twelve nuclear density locations. Within (4) hours, the contractor will provide the department with test results for the QC sample and Control Strip acceptance density. The QC sample shall be taken randomly within the first 300 tons of production not to include the first 50 tons. The Control Strip will validate the rolling pattern to be used for the remainder of the contract if the air voids from the initial QC sample taken during the control strip construction falls between 3.5% to 5.0%. If the test results do not meet these minimum requirements during the first control strip, an investigation will result and a new control test strip and new QC sample will be required. Once the contractor has proven in the control strip that he can maintain a minimum density of 89.5% density, the rolling pattern will be accepted and used for the remainder of the project. The department maintains the right to verify that the rolling pattern is maintaining a minimum density of 89.5% at any time. If the department’s test is less than 89.5%, a new control strip may be required, at the department’s discretion. QMP nuclear density testing does not apply to asphaltic base. Mixture production will be stopped and an investigation initiated if any of the following conditions occur: 1. The previous day’s maximum specific gravity average from QC testing varies by ≥ 0.020 from the value of the initial QC test; 2. If a new mix design is required (i.e, 250 number), a new test strip will be required. 3. Any other condition occurs which in the judgment of the project engineer would warrant the establishment of a new control strip density.
Submit the results to the project engineer. The Materials Reporting System is not designed to accept nuclear density test results for Asphaltic Base. Asphaltic Base is not subject to density incentive/disincentive bid items. Also note that the control strip is not to be used for gauge correlation. That procedure is to be done as described in CMM 8-15.7 and will be completed before density testing in the control strip. 8-15.16 Density Data Submittal After verifying the contractor's data, the department calculates pay adjustments using the department's MRS software. The contractor must submit the required density test information electronically using the MRS software available on the department's web site at: http://www.atwoodsystems.com/mrs/
Note: SMA and Asphaltic Base test results are recorded and submitted on DOT forms, and not submitted to the MRS system.
May 2015
Page 3
Topic E: Soils
Topic E: Soils & Aggregates
E-1
SOIL AND AGGREGATE DENSITY The Certified Nuclear Density Technicians prime responsibility is to perform density tests on HMA pavement, soils (cohesive or non-cohesive) and crushed aggregate base course. This chapter will focus only on soils and aggregates. Random sampling methodology is used to provide accurate non-biased samples and is discussed in greater detail in Topic J of this manual.
Compaction Tests are Conducted on:
Soils (Cohesive/Non-Cohesive) Crushed Aggregate Base Course Recycled Crushed Aggregate Base Course
Compaction of soils or crushed aggregate base course is the densification of loose soils by mechanical means. Densification results in a decrease of void ratio and therefore an increase of shear strength and volume stability. The improvements realized by compaction are a reduction or elimination of settlement, an increase in the bearing capacity, and a reduction or elimination of volume changes that can occur due to frost heave or swelling. The degree of compaction achieved is directly related to the material type, the compaction effort and its moisture content during compaction.
Topic E: Soils & Aggregates
E-2
VISUAL CLASSIFICATION Introduction Visual classification of laboratory or field samples is based on the Unified Soil Classification System in which the soils are divided into two broad categories: Granular soils - the proportion and gradation of the components are most significant. Cohesive soils - the degree of plasticity is the controlling factor; frequently the granular and cohesive soils will occur in combination. Granular Soils The limiting boundaries between various size ranges have been set as follows (the boundaries between “Coarse” to “Medium” and “Medium” to “Fine” are on the basis of ASTM Specifications D422-1974):
Soil Component BOULDERS COBBLES GRAVEL-Coarse GRAVEL-Fine SAND-Coarse SAND-Medium SAND-Fine
Size Range Above 8 in. 3 in. to 8 in. 3 in. to 3/4 in. 3/4 in. to No. 4 (4.76 mm) No. 4 (4.76 mm) to No. 10 (2.0 mm) No. 10 (2.0 mm) to No. 40 (0.42 mm) No. 40 (0.42 mm) to No. 200 (0.074 mm)
The shape of the gravel and coarse sand grains can be visually determined (i.e., rounded, subrounded, subangular, or angular) and should be noted on the description. Cohesive Soils Soil grains having an average particle diameter of less than 0.074 mm, the size of the openings in a U.S. Standard No. 200 sieve, are referred to as fines. They are composed of the silt and clay sizes and are identified on the basis of the degree of plasticity as well as on grain size. Size 0.005 mm is taken as the boundary between silt and clay (ASTM D 422).
Topic E: Soils & Aggregates
E-3
The following terminology is used to denote the various degrees of plasticity: Descriptive Term
Degree of Plasticity
Sandy SILT or SILT
None
SILT, trace clay, or organic SILT
Slight
Clayey SILT or organic clayey SILT
Low
Silty CLAY or organic silty CLAY
Medium
Clay or organic CLAY
High to Very High
For predominantly granular size soils with sufficient clay sizes to show marked plastic properties, it will be necessary to combine the granular and cohesive system to give the truest description possible. Such identification might be silty SAND or clayey SAND, slightly plastic. Identification Tests The following field tests may be applied to differentiate between cohesionless silt and plastic siltclay soils: 1. Dilatancy - A pat of wet soil is shaken in the palm of the hand and alternately squeezed and released. Materials which are predominantly silt will show a dull dry surface upon squeezing and a glassy wet surface upon releasing the pressure and upon shaking or vibrating the pat. With increasing clay content, this phenomenon becomes less pronounced due to lower mobility of the pore water. 2. Dry Strength - A portion of the soil is allowed to dry out completely in air. An angular fragment, about 2" in diameter of the dried material, is pressed between the fingers. Fragments with very high strength cannot be injured at all, whereas those of very low strength disintegrate completely on gentle pressure. The strength is called medium if the fragment can be reduced to powder only with great effort. Those materials with greater dry strength are predominantly clay. 3. Stickiness - A high degree of stickiness and a very smooth smear in the natural state are indicative of high plasticity. 4. Soil Thread Test - This test is an aid in estimating the degree of plasticity and differentiating between organic and inorganic soils. Take a portion of the sample, adding water as necessary, and attempt to roll it out on a flat surface with the palm of the hand into threads approximately 1/8" in diameter. Fold and repeat the procedure until thread begins to crumble into a number of small pieces. The very fact that the soil can be rolled into threads without crumbling indicates plasticity and the presence of clay. Note the number of times that the process can be repeated. This is indicative of the degree of plasticity—the greater the number of repetitions for fine soils
Topic E: Soils & Aggregates
E-4
started at the same water content, the more plastic the clay. As the plastic limit is approached, note the toughness of the threads. Highly plastic, inorganic, fat clays will feel very tough. Leaner, sandy, or silty clays will feel weak and will crumble easily. This distinction in the toughness of threads can only be felt at water contents close to the plastic limit. Organic soils and inorganic diatomaceous or micaceous soils will feel very spongy and elastic. 5. Identification may also be made on the following basis: the natural soil is molded and water content adjusted until a 1-1/2" diameter ball formed from the soil shows a flattened contact surface of 7/8" diameter when dropped from a height of two feet (gravel sizes are not included in the ball). The smallest thread possible without crumbling is then rolled from the above soil sample. The approximate relationships below are then used for identification. Thread Diameter
Descriptive Term
1/4 inch
SILT, trace clay
1/8 in. to 1/16 in.
Clayey SILT
1/32 in.
Silty CLAY
1/64 in.
CLAY
6. Dispersion Test - Silt and clay size particles can also be differentiated by determining their approximate settling rates in water. The settling rate may be measured in the field by shaking a small sample of the soil to be identified in a test tube filled with water and then allowing the particles to settle. The time required for particles to fall a distance of four inches is about 30 seconds for 0.074 mm size (the boundary between sand and silt) and about 50 minutes for particles 0.005 mm in size (the boundary between silt and clay). An approximate idea of the grain sizes present in a sample of fine-grained soil may be obtained by this method. ORGANIC SOILS Organic soils are those soils which contain sufficient organic matter, living or in the process of decay, to significantly affect the engineering properties of the soil. Topsoil, peat, and organic silt are typical examples. Organic clays are rare in New England but are common in other sections of the country. Peaty diatomaceous earth is a common organic soil found at the lower stratum of peat bogs in New England. Clay soils and organic soils may be differentiated by the following criteria:
Topic E: Soils & Aggregates
E-5
Clay Soils - Any color may be expected. For more plastic clays, appreciable effort is required to pull the material apart. The broken pieces show the structure standing on end from the pulling. For high plasticities, the smear has a shiny, waxy appearance. Organic Soils - Dark gray, black, and various shades of brown are characteristic colors. Fresh organic soils, particularly marine peats and silts, have a strong odor of hydrogen sulfide and heating the sample will intensify the odor. Less effort is required to pull fine-grained nonfibrous organic soils apart than in the case of inorganic fine grained soil and a clean break is generally formed. The smear, although smooth, is very dull and appears silty. Fibrous structure is, of course, an obvious identifying property. Organic silts respond to the dilatancy test. Organic soils invariably have very low shear strength in their natural state. UNIFIED SOIL CLASSIFICATION SYSTEM SYMBOLS GW
Well graded gravels; gravel-sand mixtures
GP
Poorly graded gravels
GM
Silty gravels; gravel-sand-silt mixtures
GC
Clayey gravels; gravel-sand-clay mixtures
SW
Well graded sands; sand-gravel mixtures
SP
Poorly graded sands
SM
Silty sand
SC
Clayey sands; sand-clay mixtures
ML
Silts; silty, very fine sands or clayey silts
CL
Clays of low to medium plasticity; silty, sandy or gravelly clays
CH
Inorganic clays of high plasticity; fat clays
MH
Elastic silts; micaeous or diatomaceous silts
OL
Organic silts and organic silty clays of low plasticity
OH
Organic clays of medium to high plasticity
NOTE Use combinations of group symbols for soils possessing characteristics of two groups: GW-GC Well graded gravel-sand mixture with clay binder
Topic E: Soils & Aggregates
E-6
Topic E: Soils & Aggregates
E-7
Topic E: Soils & Aggregates
E-8
Soils Classification According to the AASHTO system, soils are divided into two major groups and further divided into additional groups and subgroups. This section will concentrate on the two major groups. Group 1 - Granular Materials (35% or less passing No. 200 sieve) Group 2 - Silt-Clay Materials (More than 35% passing No. 200 sieve) Moreover, five soil fractions are recognized and often used in word descriptions of a material. These five fractions are defined as follows: 1. Boulders
material retained on 3-inch sieve
2. Gravel
material passing a sieve with 3-inch square openings and retained on the No. 10 sieve
3. Coarse sand
material passing the No. 10 sieve and retained on the No. 40
4. Fine sand
material passing the No. 40 and retained on the No. 200 sieve
5. Combined
material passing the No. 200. The word “silty” is applied to a silt and clay fine material having a Plasticity Index (PI) of 10 or less and the term “clayey” is applied to fine material having a PI of more than 10.
Highly organic soils such as peat and muck are not included in this classification. Because of their many undesirable properties, their use should be avoided, if possible, in all types of construction. Soil is heterogeneous. This means that soil comes in a variety of soil type combinations with a variety of properties. For example, clay or silt mixed with sand changes its properties. It slows up the intake of water and its ability to dry out. A sand with more than 15 percent silt or clay will cause it to act differently. Silty clays are difficult to differentiate. They have some of the properties of both silts and clays. If it has more than 30 percent clay, it acts like a clay. More than 20 percent silt in a soil makes it act like a silt. The finer portions of a soil composition have the greatest effect on its properties. A silty clay will dry very slowly, will take on water, is greasy and slippery, its properties change fairly rapidly, and is difficult to work with when wet. Constructing transportation facilities on the surface of the earth presents many challenges and surprises for the highway engineer. Moisture and temperature changes that occur within the upper five feet of soil have an important influence upon the engineering behavior of soil. The next section examines the soil-water relations that can have a significant effect upon the performance of a highway facility
Topic E: Soils & Aggregates
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Compaction Equipment for soils The key to obtaining good compaction of soils and crushed aggregate base course is the use of appropriate compaction equipment and methods for each type of soil or crushed aggregate base course. It is also important to have the material at or near its optimum moisture content during compaction. Compaction equipment is required to densify the material so that it can withstand loads that are placed on it. Various types of compaction methods and equipment have been designed to achieve specification compaction requirements. Four common types of rollers used to achieve compaction are briefly discussed.
Types of Compaction Equipment for Soils Vibratory Roller Sheep’s foot Roller Tamping Roller Pneumatic Rubber Tired Roller
Vibratory Roller Vibratory rollers can have a smooth steel drum as shown in the picture or the steel drums can be padded. The vibration reduces the friction between the particles and decreases the air voids. Vibrations have little or no effect on cohesive soils such as silts and clays.
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Sheepsfoot Roller Early Roman road builders would herd sheep back and forth over the base material until the road was compacted. Thus, the term “sheepsfoot” was derived as a generic term to describe studded drum rollers. Today, the term sheepsfoot is typically used to describe rollers that have long spikes projecting from the drum. The spikes penetrate through the top layer of soil and compact the underlying layer by exerting high loads of pressure per square inch (psi). As the roller moves forward or backwards, the spikes pull out of the soil and fluff the upper layer of soil. The loose top layer of soil can be beneficial or unfavorable, depending on the current soil condition. Sheepsfoot rollers work extremely well on breaking down layers of silts and clay soils. It is not as effective of a method on granular soils.
Tamping Roller Tamping rollers are similar to sheepsfoot rollers, but have lugs or pads of larger area than sheepsfoot rollers. They can operate at higher speeds, achieve a higher degree of compaction, and provide a more uniform base than a typical sheepsfoot. The tapered pads penetrate and compact the bottom layer of the soil and, as the roller propels forward or backwards, the pads can walk out of the lift without fluffing the soil on the top, leaving a fairly smooth, compacted surface. The tamping roller works well on cohesive soils (clays). A vibratory tamping roller works well on granular soils as well.
Topic E: Soils & Aggregates
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Pneumatic Rubber-Tired Roller Pneumatic rubber tired rollers provide both kneading and pressure to compact materials. It is an effective method on cohesive, granular and asphaltic materials.
Compaction Methods Section 207.3.6 of WisDOT standard specifications outline two methods of compaction—standard compaction and special compaction. Standard Compaction Standard compaction is the method used for embankment compaction unless special compaction is specified in the plans or in the contract. What they are called has nothing to do with desired results. Standard compaction does not mean a lower standard for embankment construction, nor does special compaction mean a higher standard. Regardless of the compaction method used, the aim is to achieve a degree of compaction that is satisfactory and sufficient. The determination of when a sufficient amount of compaction has been obtained is one of judgment. Density testing is usually not required as a control measure or for acceptance when using standard compaction. Different types of soils will require different degrees of effort to obtain the required compaction. As previously stated, generally soils will compact most readily to 90% when their moisture content is between 90 to 110 percent of the optimum moisture content. A simple test can be performed to get a rough idea of a soil’s moisture content. Take a handful of soil and form it into a compact ball in your hand. If the soil cannot be formed into a compact ball, then the soil is too dry. Spit on the ball. If the spit remains on the surface of the soil, then it is too wet. If the moisture is slowly absorbed into the soil ball, then proper moisture has been Compaction can be categorized as shallow compaction or deep compaction, based on the extent of treatment. Shallow compaction is performed on soft in-situ soils or on earth fills, while deep compaction is performed on in-situ soils at greater depths. The inspection of embankments compacted under standard compaction procedures is as essential as inspection for embankments built under special compaction procedures. The grade inspector
Topic E: Soils & Aggregates
E-12
or project engineer should ensure that each layer placed meets the thickness requirements and is uniformly compacted across the full width of the embankment to the required degree. To provide a record of compaction effort and achievement, the grade inspector should make at least one entry per day in the diary for each embankment constructed, excluding minor fills. Special Compaction If special compaction is required for embankments, QMP soils, mechanically stabilized earth (MSE) walls, or base courses, then check the special provisions and design criteria of the project for additional information. In most cases, specifications will require that the soil be compacted to a dry density that is 90 to 95 percent of the maximum dry density as determined by the laboratory Proctor test. Special compaction involves laboratory testing and field inspection and testing. The engineer determines the maximum density and the optimum moisture content of the material by performing the Proctor test, as stated in the specifications. The contractor is responsible for ensuring the proper moisture content of the soil or aggregate, for selecting proper compaction equipment, and for determining the amount of effort that is needed in order to consolidate the material to the specified density. It is the responsibility of the inspection forces to determine whether or not the embankment materials have been satisfactorily compacted. Density tests, according to AASHTO T 310 (WisDOT modified), for determining the in-situ density of the compacted material, should be taken as frequently as necessary for adequate control under particular job circumstances. Moisture-Density Relationship Different types of soils or aggregates will require different amounts of effort to obtain compaction that meets the target density. The moisture content of the materials will influence the degree of density attained during compaction. Proctor R.R. Proctor developed the fundamentals of soil compaction in the early 1930s. He established that the degree of compaction of a soil depends on the soil dry unit weight, moisture content, grain size distribution, and on the magnitude of the mechanical energy imparted on the soil. When water is added to a soil during compaction, it acts as a lubricating agent, causing soil grains to slip on each other and attain more efficient packing (higher dry unit weight). As the water content is increased, a point is reached beyond which any addition of water to the soil mass will result in a decrease of the dry unit weight (dry density). This is because water will occupy void spaces otherwise occupied by solid grains. The moisture content at which the maximum dry unit weight is achieved for a given compactive energy is called the optimum moisture content. The Proctor compaction tests are used in the laboratory to establish the dry unit weight-moisture content relationship of a soil to determine its compaction properties. Specifically, the Proctor test
Topic E: Soils & Aggregates
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is used to determine the maximum dry density of a soil, and the moisture content at which the maximum density is achieved. There are two Proctor tests that are often used—AASHTO T 99 which is referred to as the standard Proctor test and AASHTO T 180, referred to as the modified Proctor. A typical moisture-density relationship of soils is depicted in the graph. The material’s dry density is plotted against the water content and a test curve is drawn through all of the points. The top of the curve represents the maximum dry density for the soil type. The center of the curve represents the optimum moisture content at which the maximum dry density is achieved. The primary difference between the standard and the modified Proctor tests is the laboratory compaction effort used to prepare the soil specimen—it is much higher using the modified Proctor test. The following graph shows the moisture-density relationships of several common material types. The graph shows that a crushed aggregate base course will achieve a much higher maximum dry density at lower moisture contents than a silty sand or fat clay.
A.) Crushed aggregate base course B.) Gravel with sand C.) Sand D.) Silty sand E.) Fat clay
Moisture Density Relations of Soils Using a 5.5-lb Rammer and a 12-in. Drop (AASHTO T 99) In the Standard Proctor Test, the soil sample is placed into a 4-inch or 6-inch diameter mold in three layers of equal height for a total compacted depth of 5 inches. Each layer is subjected to 25 blows if using 4-inch molds or 56 blows if using 6-inch molds by a rammer that weighs 5.5 pounds and free falls 12 inches, for a compaction force of 12,400 foot pounds. The test is repeated with the same soil sample at different amounts of moisture until enough points are established to plot the dry unit weight-moisture content curve. Moisture Density Relations of Soils Using a 10-lb Rammer and an 18-in. Drop (AASHTO T 180)
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With the Modified Proctor Test, the soil sample is placed into a 4-inch or 6-inch diameter mold in five layers of equal height for a total compacted depth of 5 inches. Each layer is subjected to 25 blows if using 4-inch molds or 56 blows if using 6-inch molds by a rammer that weighs 10 pounds and free falls 18 inches. The compaction force of this test is 56,200 foot pounds—much greater than that of the standard Proctor test. Thus, the maximum dry density obtained using the modified Proctor is higher than that obtained using the standard test. This test is also repeated with the soil at different moisture levels until enough points are obtained to plot the dry unit weight-moisture content curve. The table below shows a simple comparison of the two Proctor tests.
AASHTO Sieve Size Mold Diameter Lifts Compacted Depth Blows Rammer Fall Height
Proctor Comparison (simplified) T 99 T 180 No.4 or 3/4 –inch No.4 or 3/4 –inch 4-inch or 6-inch 4-inch or 6-inch 3 5 5 inches 5 inches 25 (4” mold) or 56 (6” mold) 25 (4” mold) or 56 (6” mold) 5.5 lbs. 10 lbs. 12 inches 18 inches
WisDOT requires that a minimum of five Proctor points be used to plot the density-moisture curve—two ascending points, two descending points, and one at or near the optimum moisture content. Note: AASHTO T 180, Moisture-Density Relations of Soils Using a 10-lb Rammer and an 18 in. Drop, the modified Proctor, is used on QMP Base Aggregate ONLY. Family of Curves—One-Point Method (AASHTO T 272) A family of curves, as shown in the graph on the previous page, can be used for a quick determination of the maximum density and optimum moisture content of a soil from a particular source using only one Proctor point. If a family of curves is developed for a particular source, then this one-point procedure can be used to test a material from that source, following the same method (A, B, C, or D) that was used in the Proctor test to plot the family of curves. The single Proctor point that is determined from the test can be plotted on the family of curves, to determine the maximum dry density and optimum moisture content of the material.
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The sample preparation and test procedure involved in the standard and modified Proctor tests are similar for each respective test method, with the exception of the number of lifts compacted, the rammer weight, and the drop height. The following example lists the basic steps involved with the standard Proctor test—AASHTO T 99, Method C. Steps of Test Procedure T 99, Method C for a soil sample 1.
Obtain a sample of roughly 25 pounds (11 kg). If the sample is damp when received from the field, then dry by air or by heat not to exceed 140oF.
2.
Thoroughly break up the sample and run it all through a ¾” sieve.
3.
Weigh the material that passed thru the ¾"sieve (P¾) and the material retained (R¾) and calculate the percentage of R¾ (PR3/4).
If the PR3/4 material > 5%, then a coarse aggregate correction factor needs to be applied at the end of the test. If the PR3/4 material > 30%, then this test procedure cannot be used. Discard or set aside the R¾ material and run the test on the material that passed through the ¾" sieve (P¾). Test will be run at 2, 4, 6, 8, and 10 percent moisture contents with the P¾ material.
4.
Select a representative sample of the P¾ material that is at least 11 pounds and thoroughly mix it with enough water so that it is roughly four percent below its optimum moisture content.
5.
Form a specimen by compacting the sample into a 4-inch mold (with collar attached) in three equal layers for a total compacted depth of about five inches. Compact each layer with 25 uniformly distributed blows from the rammer, dropping free from a height of 12 inches above the elevation of the soil.
6.
After all three layers have been compacted, remove the extension collar and carefully trim the compacted soil even with the top of the mold by using a straightedge. Patch any holes that develop in the surface (by removal of coarse material with the straightedge) with smaller-sized material.
7.
Weigh the mold with the moist soil.
8.
Subtract the weight of the mold from the weight of the mold with the moist soil to determine the weight of the moist soil specimen. Then multiply that by the mold factor, which is shown in Table 3 of AASHTO T 99, to determine the wet weight by cubic foot of compacted soil. For Method C, the mold factor is 30.
9.
Remove the material from the mold and slice it vertically through the center. Take a sample of the material from one of the cut faces (500 grams minimum) and weigh it immediately. Then dry it to a constant weight to determine its moisture content (Msample). Msample=
Weight of Water lost Weight of Dry Soil Sample
x 100
Topic E: Soils & Aggregates
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10. When the moisture content is known (x-coordinate), the oven-dry density (Doven-dry)(ycoordinate) can be calculated as follows: Wet Density
Doven-dry = (% moisture content+100) x 100 11. Thoroughly break up the remainder of the material until it will all pass through a ¾-inch sieve and about 90 percent of it will pass a No. 4 sieve, as judged by the eye, and add it to the remaining portion of the sample. 12. Add water to increase the moisture content of the soil sample by one or two percent. 13. Repeat steps 4 through 12 above and continue the series of tests until there is either a decrease or no change in wet weight per cubic foot of the compacted soil. WisDOT requires that at least 5 points to be used for plotting the graph. 14. Plot the moisture content (x) versus the dry densities (y) of the Proctor points on a graph. 15. Select the maximum dry density (DMAX ) and optimum moisture content (MOPT) from the graph. 16. Apply coarse aggregate correction factor if applicable (see step 3). The procedure for correction is explained below.
Topic E: Soils & Aggregates
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Correction of Maximum Dry Density and Optimum Moisture for Oversized Particles AASHTO T99 Annex A and AASHTO T180 Annex A Since the large sized particles are removed from the soil sample before conducting the Proctor tests (AASHTO T 90 or AASHTO T 180), we will have removed the densest material (by volume). That can be briefly explained as follows: Specific gravity is a measure of a material’s density as compared to the density of water. The specific gravity of water, by definition, is 1. The specific gravity can also be determined by dividing the dry weight of a solid mass by the weight of that same solid mass when it is submerged in water. Regardless of which ratio you use, the units will cancel each other out and the result will be the specific gravity, which is unitless. The specific gravity of a material (X) can be determined by the ratio of the density of that material divided by the density of water. Specific Gravity of X=
Density of X Density of Water
The density of water is not an absolute density because it varies based on the water’s temperature. Water is most dense at 39.2oF (4°C); at that temperature it has a density of 1 gram/cm3 = 62.4 lb/ft3, which is the density that is used in most calculations. AASHTO recommends using 2.6 as the specific gravity of coarse particles, unless the specific gravity of the coarse particles is determined in the laboratory. Thus, we can use the specific gravity of 2.6 and multiply it by the density of water (62.4 lb/ft3) to determine the density of that coarse material 2.6 x 62.4 lb/ft3 = 162.2 lb/ft3. Previous laboratory Proctor tests have shown that the maximum density of our crushed stones or gravel usually range between 135 and 145 lb/ft3. So, a solid cubic foot of stone has a greater weight and is denser than that of its crushed components.
Since we remove the largest and densest particles from our laboratory Proctor tests, the results will be less than they would be if the large stones were left in. So, the maximum density and the optimum moisture content that is determined from the Proctor graph needs to be adjusted higher to compensate for the percentage of coarse particles that were removed to be more representative of the entire material sample, thus more representative of the material used in construction. The procedure and calculations to determine the corrected optimum moisture content and the corrected maximum dry density are detailed in Annex A of AASHTO T 99 and AASHTO T 180, and are summarized in the following section.
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Correction of Maximum Dry Density and Optimum Moisture for Oversized Particles Correction Definitions DMAX = dry density of material passing 3/4" sieve (P¾) in lb/ft3) NOTE: This is Maximum Density from the Proctor curve PR3/4 = percent retained on 3/4" sieve (R¾) expressed as 0.0 % NOTE: Not as a decimal PP3/4 = percent passing through 3/4" sieve (P¾) expressed as 0.0% NOTE: PP3/4 = 100 - PR3/4 (Not a decimal) k = Bulk Specific Gravity (Gsb) of R¾ x 62.4 lb/ft3 NOTE: Wisconsin uses a Gsb = 2.65, therefore k = 165.4 lb/ft3 MOPT = Optimum Moisture Content of P¾ material (obtained from Proctor curve) MR3/4 = Moisture Content of R¾ (actual as measured or assumed at 2.0%)
Correction Equations: Corrected Maximum Dry Density =
(100) (DMAX ) (k) (DMAX )(PR3/4 ) + (k) (PP3/4 )
Corrected Optimum Moisture Content =
(MOPT ) (PP3/4 ) + (MR3/4 ) (PR3/4 ) (100)
Typical Corrections Corrected dry density is an increase of about 1 to 5 lb/ft3 Corrected optimum moisture is a decrease of about 0.1 to 1 %
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STUDENT PROBLEM #1: MOISTURE-DENSITY RELATIONSHIP The moisture/density relationship of clay Proctor is 132.9 lb/ft3 at 10.1% moisture content. Part 1—calculate the percentage of optimum moisture for each of the five density gauge readings shown below. Part 2—calculate the percent compaction at each test location. Required density is 95.0 percent of maximum dry density as determined by AASHTO T-99.
Lift #-Test #
Dry Density (lb/ft3)
% Moisture
1-1
123.3
10.4
1-2
134.3
9.6
2-1
135.8
11.2
3-1
135.0
10.8
3-2
131.6
9.2
% of Optimum Moisture
Percent Compaction
FORMULAS: % of Optimum Moisture = % Compaction =
𝐴𝑐𝑡𝑢𝑎𝑙 𝑀𝑜𝑖𝑠𝑡𝑢𝑟𝑒 % 𝑂𝑝𝑡𝑖𝑚𝑢𝑚 𝑀𝑜𝑖𝑠𝑡𝑢𝑟𝑒 %
x 100
𝐹𝑖𝑒𝑙𝑑 𝑀𝑒𝑎𝑠𝑢𝑟𝑒𝑑 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 x 100 𝐾𝑛𝑜𝑤𝑛 𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝐷𝑒𝑛𝑠𝑖𝑡𝑦
Consider: What needs to be done with the above tests? They are 1-1, 1-2, 2-1, 3-1, 3-2.
Hint: We know compaction and moisture are related. How will we handle the situation? Consider if our samples are way too wet or way to dry. Each lift has to be corrected separately.
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SOLUTION FOR STUDENT PROBLEM #1: MOISTURE-DENSITY RELATIONSHIP
Solution for Part 1 (% of Optimum Moisture): % of Optimum Moisture =
𝐴𝑐𝑡𝑢𝑎𝑙 𝑀𝑜𝑖𝑠𝑡𝑢𝑟𝑒 % x 100 𝑂𝑝𝑡𝑖𝑚𝑢𝑚 𝑀𝑜𝑖𝑠𝑡𝑢𝑟𝑒 %
% of Optimum Moisture =
10.4 % x 100 = 102.97 = 103% 10.1 %
Solution for Part 2 (Percent Compaction): % Compaction =
𝐹𝑖𝑒𝑙𝑑 𝑀𝑒𝑎𝑠𝑢𝑟𝑒𝑑 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 x 100 𝐾𝑛𝑜𝑤𝑛 𝑀𝑎𝑥𝑖𝑚𝑢𝑚 𝐷𝑒𝑛𝑠𝑖𝑡𝑦
% Compaction =
123.3 x 100 = 92.77 = 92.8 132.9
Dry Density (lb/ft3)
% Moisture
% of Optimum Moisture
Percent Compaction
Lift 1- 1) 123.3
10.4
103.0
92.8
1-2) 134.3
9.6
95.0
101.1
Lift 2-1) 135.8
11.2
110.9
102.2
Lift 3-1) 135.0
10.8
106.9
101.6
3-2) 131.6
9.2
91.1
99.0
What should your recommendation be for the above tests? 1. Add water and disk or wait for additional moisture to absorb and retest. 2. Everything is OK.
Topic E: Soils & Aggregates
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Backfill Fill material is usually placed in layers (lifts) having a loose thickness of eight inches. Each lift is compacted by several passes of a compaction roller. Field tests are then performed to determine the in-situ (compacted) soil density. If the in-situ dry unit weight is not within the specified percentage of the maximum dry unit weight, then the soil should be compacted more. The number of roller passes required to result in acceptable compaction is then determined. As long as the fill moisture content and the lift thickness remain the same, the compaction is controlled by making sure that the roller makes a sufficient number of passes over each lift. Periodically, insitu dry unit weight tests are performed to verify that the in-situ fill dry weight is within specifications. MSE Wall Backfill Checklist
Check that the backfill material complies with the plan specifications or the manufacturer’s recommended gradation, whichever is more restrictive. Conduct gradation tests, or submit samples to soils testing lab, on the backfill material. Material not conforming to the plans, specifications, and contract documents shall not be used. Obtain from the contractor certified test results showing that the backfill material meets the pH, sulfate, chloride, organic content, and electrical resistivity requirements specified. Test results must be from a certified independent lab and less than six months old. Measure the thickness of each backfill lift. It is not to exceed 8 inches (200 mm). Each layer shall be adequately compacted before the next lift is placed. To achieve adequate compaction, ensure that the backfill behind the wall is compacted to a minimum of 95.0 % of its maximum density as determined by AASHTO T-99, Method C. Backfill shall be spread by pushing it parallel to the concrete panels. Ensure that metal tracks of earth-moving equipment never come in contact with the metal reinforcement. Check that the first lift of backfill is not placed and compacted directly against the panels since the panels may be pushed off-line. Ensure that the contractor checks the batter and alignment of the wall after each lift is placed. If adjustments are necessary, they should be made by the contractor before wall construction proceeds further. If excessive panel movement or backfill pumping is noticed during construction, gradation and moisture of the backfill should be tested. Check to see that the slope behind the wall is sloped away from the back of the concrete panels to divert water run-off from the wall area. Refer to Section 206 of the Standard Specifications for further guidance as to how backfill should be placed.
Topic E: Soils & Aggregates
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Procedure for Establishing a Moisture Density Gauge Bias for Soils A density gauge measures the moisture content simultaneously with the in-situ density of a compacted material. A moisture bias represents the average difference in moisture content between in-situ nuclear gauge measurements and oven-dried samples for a particular nuclear gauge and a particular type of material. Determine a moisture gauge bias for every different type of soil or aggregate base at startup of testing and during gauge correlation. Use the following procedure to establish the correct bias for any particular type of soil or base. Procedure: 1. Use the density gauge to measure the in-situ moisture content, wet density and dry density of a compacted soil base. Take gauge readings, in backscatter mode, at two different locations with the same soil type. 2. Dig a hole about 6 inches in diameter and 6 inches deep and obtain a 150-gram to 200gram sample of the soil directly beneath the center of the gauge footprint at both test locations. 3. Weigh each wet sample. Oven-dry the wet samples at 110°C, until sample weights remain constant. Weigh each, now dry sample. 4. Calculate the oven-dry moisture content (%) of each soil sample (Msample). Msample (%) =
Weight of Water Lost (Wet Weight−Dry Weight) Dry Weight
x 100
5. Determine the oven dry moisture content for each test site from the gauge measurements (Msite), in pounds per cubic foot, and calculate the average. Msite = Where:
Msample x Dgauge (Msample + 100)
Msite = moisture content at test sites, pcf Msample = moisture content of samples, % of dry weight (step 3) Dgauge = gauge measured density, pcf (from step 1)
6. Determine the correction factor (moisture gauge bias) for each site and then average the two values. MBias (pcf) = Msite - Mgauge The average of the two bias values is the gauge moisture bias. This value can be used for all field testing of that project with that gauge for that same soil type. Follow CMM 8-15-12.2 for the procedure to enter the moisture bias into the gauge; some gauges require additional calculations.
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Student Problem #2: Moisture Density Gauge Bias Determine the material moisture bias for a specific soil type on a project. The following gauge measurements and soil samples were obtained from two locations: Gauge Reading Location #1 Location #2
Sample Wet Weights 677 gm 750 gm
Density (Dgauge) pcf 123.3 134.3
After drying in forced air oven at 230 degrees, dry weights:
Sample #1 Sample #2
Sample Dry Weights 642 gm 721 gm
Total Moisture (Mgauge) pcf 10.4 9.6
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Solution to Student Problem #2: Moisture Density Gauge Bias Determine the oven-dry moisture content of the two samples (Msample). Calculate the oven dry moisture content of each test site (Msite). Determine the correction factor (moisture gauge bias). Msample (%) = Msite =
Weight of Water Lost (Wet Weight−Dry Weight) Dry Weight
Msample
x 100
x Dgauge
(Msample+ 100)
MBias (pcf) = Msite - Mgauge Sample/Site #1 Msample#1 (%) = Msite#1 (pcf) =
677−642
Gauge test results: Dgauge#1 = 123.3 pcf Msite#1 = 10.4 pcf DryDgauge#1 = 112.9 pcf Msample#1 = 5.5 %
x 100 = 5.5 %
642
5.5 x 123.3 (5.5+ 100)
= 6.4 pcf
MBias#1 = Msite#1 - Mgauge#1 = 6.4 - 10.4 = -4.0 pcf Sample/Site #2 Msample#2 (%) = Msite#2 (pcf) =
750−721
Gauge test results: Dgauge#2 = 134.3 pcf Mgauge#2 = 9.6 pcf DryDgauge#2 = 124.7 pcf Msample#2 = 4.0 %
x 100 = 4.0 %
721 4 x 134.3 (4 + 100)
= 5.2 pcf
MBias#2 (pcf) = Msite#2 - Mgauge#2 = 5.2 – 9.6 = -4.4 pcf
Sample Msample
Msite
minus Mgauge
=
MBIAS
DryD gauge
#1
5.5%
6.4
-
10.4
=
-4.0
112.9
#2
4.0%
5.2
-
9.6
=
-4.4
124.7
Bias -4.2 Avg
minus Avg = Bias - (-4.2) = -
(-4.2) =
Ddry-corrected 117.1 128.9
TOPIC F: Private Transportation and Storage of Nuclear Density Gauges/Meters
Topic F: Private Transportation and Storage
F-1
Motor Vehicle Transportation
Transporting any nuclear density gauge/meter by vehicle requires: Transportation of Nuclear Density Gauge/Meter
Placed in approved Type “A” shipping container. Properly secured and braced. Never placed in passenger compartment, cargo area only. Hazmat Training.
Practice ALARA (As Low As Reasonably Achievable) at all times to minimize your risk to unnecessary radiation exposure at all times. Regulatory agencies have set specific occupational exposure limits for personnel working with radiation. Bill of Lading/Shipping Papers
Emergency response procedures Within arms reach of driver while restrained by a seat belt When the gauge is locked up and out of the operators sight, shipping papers must be on driver’s seat or in the drivers side door storage compartment
Topic F: Private Transportation and Storage
F-2
HAZMAT Training HAZMAT = HAZARDOUS MATERIALS .
HAZMAT Training 172 CFR subpart H requires that every HAZMAT employer train, test, certify and maintain records for each HAZMAT employee. HAZMAT employer/employee applies to anyone who transports, or anyone who prepares for transport, radioactive materials. HAZMAT training can be obtained from the nuclear gauge manufacturer, but actual course certificate must be endorsed by the company/agency RSO. To remain in compliance, this training must be repeated at intervals not to exceed 3 years. If shipping by air (IATO), this training must be repeated at intervals not to exceed 2 years, to remain in compliance.
Storage of Nuclear Density Gauge/Meter
Storage of Nuclear Density Gauge/Meter Field storage must be approved by agency/company Radiation Safety Officer (RSO). Shall not be stored in private homes, garages or unauthorized buildings, unless approved by the NRC or Wisconsin Agreement State License. Storage location must have readings below the 2 millirem an hour or 100 millirem a year. Always store in locked shipping container. Should notify appropriate civil authorities (e.g., fire department) Lock area where meter is to be stored, must have the three-lock rule. Placard a warning sign and list emergency phone numbers.
Topic F: Private Transportation and Storage
F-3
Safety First WisDOT requires wearing the appropriate safety apparel when conducting nuclear density testing. The appropriate safety apparel should include:
Appropriate Safety Apparel
Hard Hat Hard Toe Shoes Protective Vest Reflective Pants
Topic F: Private Transportation and Storage
F-4
The danger encountered by a nuclear density technician may involve: 1) high traffic conditions, 2) large heavy compaction equipment and 3) asphalt paving equipment. Remember, always use good judgment and common sense whenever working on, near or around highway construction projects. Personnel Monitoring Device A personnel monitoring device, such as a film badge, TLD badge, or an OSL badge, is required Three Types of Personnel Monitoring Devices Film Badge TLD Film Badge OSL
to be worn at all times if required by the companies license. The purpose of the personnel-monitoring device is to document the low-level occupational radiation exposure during nuclear density gauge operation. Film Badge Film badges contain special film that darkens when exposed to radiation. A dose level is determined based on the darkness of the film. Film badges are prone to error, such as fogging due to excessive heat or light. TLD Badge TLD (Thermo Luminescent Dosimeter) badges incorporate a new technology, which utilizes solid crystals or phosphors to determine the amount of radiation exposure. TLD’s are more accurate than film badges. OSL Badge In the new badge, this function is accomplished using optically stimulated luminescence (OSL) from aluminum oxide. Both old and new badges use CR-39 polycarbonate to measure neutron exposure. OSL represents a recent advancement in passive radiation dosimetry. During processing, the aluminum oxide sensing elements are illuminated with an array of LEDs, causing them to luminesce in proportion to the amount of ionizing radiation received. OSL dosimetry has a number of advantages over TLDs, including the ability to re-read sensing elements at times when results are questionable.
Topic F: Private Transportation and Storage
F-5
Film badges must be processed on a monthly basis while TLD’s badges may be processed monthly or quarterly. Occupational Radiation Exposure Limits Whole body dose limit = 5000 millirems per year In Wisconsin, if younger than 18 years of age, you are not allowed to work with radioactive material. Pregnant women (that declare in writing they are pregnant) = dose limit during pregnancy, monthly, maximum cannot be > 500 millirems during the term is limited to 500 millirems.
Methods to Reduce Radiation Exposure The only three factors to consider when looking for ways to reduce exposure are time, distance and shielding. Methods to Reduce Radiation Exposure Time Time The simplest way to reduce exposure is to limit the Distance time spent near a radioactive source to a minimum. Shielding To reduce the amount of exposure while operating a nuclear density gauge/meter, always stand at least 1 meter (3 feet) from the gauge. Distance Distance is a very effective means of limiting exposure to radiation. Gamma rays, and all other forms of electromagnetic radiation, become less intense at the rate of the square of the distance from the radiation source. By the Inverse Square Law, a small increase in distance results in a large drop in exposure. Therefore, if the D1 2 ] I2= I1 [ distance from the D2 radioactive source is doubled then the exposure intensity is reduced one quarter as much.
Shielding Shielding of gamma radiation sources used in density gauges by adding a high-density material between the operator and the source will lower the potential for radiation exposure.
Topic G: Troxler, Humboldt, and CPN Nuclear Density Gauge Operation and Procedures
Topic G: Troxler, Humboldt, and CPN Nuclear Density Gauge Operation and Procedures
Requirements for all WisDOT Nuclear Gauge Operators
Manufacturer’s Nuclear Density Gauge Training Course or Other Approved Courses by NRC or Agreement States (Wisconsin is an agreement state) WisDOT/UWP Certified Nuclear Density Gauge Technician I Course
G-1
Radiation Theory Two Types of Radioactive Isotopes
Cesium-137 Produces Gamma (photons) Radiation Gamma radiation measures density Americium-241: Bereryllium Produces fast neutrons (electrons) Fast neutrons measure moisture
Operation of Troxler Nuclear Density Gauge The nuclear density gauge can be utilized effectively to monitor the density and moisture content of most construction materials. The construction materials include cohesive and noncohesive soils, crushed aggregate base course and asphaltic concrete pavement. The prerequisites for using a nuclear gauge on WisDOT projects include: 1) manufacturer’s nuclear gauge training course, 2) personal monitoring device, and 3) WisDOT/UWP Certified Nuclear Gauge Technician I course. Troxler gauges used on projects will consist of model 3440, 3411, 3430, 3440, and 3450.
The Troxler nuclear density gauge uses two radioactive isotopes to determine moisture and density. The two radioactive isotopes are Cesium 137 and Americium of 241:Beryllium. Beryllium is mixed with Americium to stabilize the element. The radioactive isotope Cesium-137 produces gamma (photon) radiation. Gamma (photon) radiation is used to measure density.
Topic G: Troxler, Humboldt, and CPN Nuclear Density Gauge Operation and Procedures
G-2
Troxler Nuclear Density Gauge Testing Modes
Backscatter
Direct Transmission
The higher the gamma (scattered photon) count, the lower the density; inversely, the lower the gamma (scattered photon) count, the higher the density.
Remember: The material closest to the gauge has the greatest influence on the count. Surface roughness and surface preparation have a direct correlation with the accuracy of the information. The mixing of radioactive isotopes Americium-241:Beryllium produces a fast neutron. Fast neutrons specifically measure moisture. The Troxler Nuclear Density Gauge testing modes consist of 1) backscatter and 2) direct transmission. Backscatter The backscatter mode is obtained by locating the first position on the Troxler Nuclear Density gauge handle. The backscatter mode is enabled to conduct a nondestructive test. The gamma radiation source is located at the end of the source rod. The end of the source rod has been encapsulated to provide safe operation. At no time is the nuclear density gauge operator to touch or handle the end of the source rod. The source rod set in the backscatter position is located ¼ inch off the testing surface. The backscatter position works by emitting gamma (photons) radiation into the testing material and the gamma radiation is measured at the opposite end of the gauge by Geiger-Mueller detector tubes. The measured gamma radiation (scattered photons) is counted by the two sets of the Geiger-Mueller detector tubes. The higher the gamma (scattered photon) count the lower the density; inversely, the lower the gamma (scattered photon) count the higher the density. The gamma (scattered photon) radiation count is directly inversely proportional to the density. Keep in mind, the material closest to the gauge must be flat and devoid of imperfections.
Topic G: Troxler, Humboldt, and CPN Nuclear Density Gauge Operation and Procedures
G-3
Direct Transmission The direct transmission testing is conducted by inserting the source rod directly into a premolded pilot hold. Troxler manufactures different types of nuclear density gauge meters with either an 8 or 12-inch source rod. Direct transmission testing is a destructive test procedure utilized in the testing of soils and crushed aggregate base course. WisDOT puts specifications require 8” lifts which compact down to approximately 6” or 25% mass. Internal Troxler Nuclear Density Gauge Operation
Geiger-Mueller Tubes
Encapsulation of Source Rod
Tungsten Shield
Tungsten Sliding Block
Geiger-Mueller Tubes The Troxler nuclear density gauge uses two sets of Geiger-Mueller (G-M) tubes that are located near the back of the gauge and are used for detecting scattered photons or gamma radiation. When the source rod is set into “measuring” position, the source and detectors are in the same horizontal plane. Ideally, no photons should reach the detectors in a path direct from the source. In the “backscatter mode,” the photons must be scattered at least once before reaching the detectors. Photons reaching the G-M detectors are counted for selected intervals of time. For this reason, WisDOT has selected and established a test duration of four minutes for all nuclear density tests. The number of photons counted is directly related to the density of the material. The nuclear density gauge uses counts to determine the density of the material. For example, the higher the counts, the lower the density.
Topic G: Troxler, Humboldt, and CPN Nuclear Density Gauge Operation and Procedures
G-4
Encapsulation of Source Rod The radioactive materials used in Troxler gauges are all classified as special form, encapsulated sealed sources. Typically, the gamma source, cesium 137 is first fused with a ceramic to form a small bead. This bead is then formed by fusion welding inside a stainless steel capsule, which is in turn welded inside the stainless steel source rod. The source encapsulation and shielding is designed to stop all alpha and beta particles produced by the radiation source. The main health concerns affiliated with the use of Troxler nuclear density gauge is exposure to necessary gamma and fast neutron radiation. The annual occupational maximum exposure limit is 5000 millirems for adults. Practice ALARA at all times to minimize all types of radiation exposure. Tungsten Shield Mechanism The tungsten shield mechanism is where the source rod is housed. Beneath the tip of the source rod is a tungsten shield mechanism, which operates like a shutter and also provides radiation protection.
Tungsten Sliding Block The tungsten sliding block mechanism periodically will require cleaning when the source rod is difficult to engage. An improperly operating sliding block mechanism may be a contributing factor to erratic density readings. When conducting any maintenance cleaning activities, always check and follow all
Topic G: Troxler, Humboldt, and CPN Nuclear Density Gauge Operation and Procedures
G-5
prescribed Troxler nuclear density gauge operating and maintenance procedures. Calibration of Troxler Nuclear Density Gauge Wisconsin Department of Transportation (WisDOT) requires a nuclear density gauge to be calibrated annually within the current construction season before being allowed on any of their projects. A typical manufacturer’s calibration includes correlating the nuclear density gauge to 3 different calibration blocks of known material and density. The annual calibration is necessary to document and make the necessary calibration adjustments to the ever-changing radiation isotope decay process. The annual calibration process will ensure the nuclear density gauge is operating properly and the test results are as accurate as possible. Also, the annual calibration of the nuclear density gauge is absolutely necessary in order to correlate the results between similar and different types of nuclear density gauges used on WisDOT nuclear density quality management program projects. Daily Reference Standard Count The low level radioactive source undergoes a natural decay process, which results gradual loss of strength. To compensate for the source decay a daily reference standard count is performed each workday. It is absolutely necessary to ensure the highest accuracy and precision possible. All daily standard counts must be recorded in a daily standard count logbook and be kept with each gauge. NOTE: This daily reference standard count has to be performed on material that is above 100 lbs/cubic foot density.
Manual assembly note: Insert yellow copy paper divider here
ASTM D 2950 (WisDOT Modified)
1 of 4
Density of Bituminous Concrete In-Place by Troxler /CPN Nuclear Methods
Significance and Use This test is used as a rapid nondestructive technique for determining the in-place density of compacted asphaltic concrete mixtures. The nondestructive technique utilizes the backscatter method along with gamma and neutron radiation to determine density and moisture on surface only, respectively.
1 Unsecure and unlock properly approved shipping container and nuclear gauge/ meter.
4 Obtain maximum lab density value from project engineer and enter into gauge/meter. Press the “SHIFT” and “MODE” keys and follow the displayed instruction to set the gauge in the appropriate mode.
2 Conduct recommended manufacturer’s warm up procedure for nuclear gauge (Refer to page J-4 and J-5). Equipment 1. Troxler Nuclear Density Gauge 2. Mfg. Standard Block 3. Approved Storage Container 4. Bill of Lading Materials 5. Appropriate Safety Apparel 6. Test Data Forms
5 Next, press the “TIME” and the “2" keys to enter the test duration of 4 minutes,By following the window instructions
3 Determine random sampling method for using method ASTM D 3665 to locate test area. Test area: Soils or HMA
ASTM D 2950 (WisDOT Modified)
2 of 4
Density of Bituminous Concrete In-Place by Troxler/CPN Nuclear Methods
6 Place gauge on asphaltic surface. Check rocking using alternate corner method.
8 Release lockingmechanism and set gauge/meter in backscatter mode.
10 Retract source rod and secure nuclear gauge meter.
7 Always place nuclear density gauges parallel with the paving operation. Mark gauge outline. Use arrow to point in direction of source.
9 Press START /ENTER key. After 4 minutes, the density and compaction values will be displayed. Always practice ALARA by standing at least 1 meter (3 ft) from nuclear density gauge/meter until the 4 minute test cycle has been completed.
11 Record test data on worksheet.
Direction of Source 12 Return gauge to proper storage container and secure.
AASHTO T 239/238 (WisDOT Modified) Moisture/Density of In-Place Soil-Aggregate by Troxler/CPN Nuclear Methods
6 Use a tile spade or equivalent to remove all loose and disturbed material as necessary to expose a flat surface to be tested.
Note: The placement of the gauge on a flat surface of material to be tested is critical to the actual moisture/density determination.
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10 Keeping your foot on the scraper plate, use the extractor tool to remove the drill rod from the soil and then trace around the
Note: Removing the top surface will ensure a representative moisture will also be tested.
9 Once the surface has been 7 Prepare a horizontal area sufficient in size to accommodate the gauge, by planing the area to a smooth condition so as to obtain maximum contact between the gauge and material being tested.
properly prepared, place the scraper plate on the test surface and put the extractor tool and drill rod on the scraper plate guide. Securing the scraper plate with one foot, use a hammer to drive the drill rod into the ground the appropriate depth.
Note: The drill rod pilot hole must exceed the depth of the source rod by two inches. 8 The maximum void beneath
the gauge shall not exceed 1/8 in. (3 mm) and the total area filled beneath the gauge should not exceed 10 percent. Use native fines to fill these voids and then smooth the surface with a rigid plate or other suitable tool.
perimeter of the scraper plate with the tip of the drill rod. 11 Ensure base of nuclear gauge is clear of any debris which could lower the actual density reading.
AASHTO T 239/238 (WisDOT Modified)
4 of 4
Moisture/Density of In-Place Soil-Aggregate by Troxler/CPN Nuclear Methods
12 Place the nuclear gauge/meter within the prescribed marked area. Pull the trigger in the gauge handle and lower the source into the drill rod hole, making sure the rod indexes properly at the correct depth.
14 Press the START/ENTER key. After the four minute reading, all moisture and density values will be displayed along with percent compaction. Make sure to record the data on the prescribed worksheets.
Note: Per WisDOT Spec. the maximum thickness of the loose material is placed at 8”, maximum depth of test is not to exceed 6”
Note: The information may be stored in the gauge by pressing the
STORE key. Note: This operating procedure allows for safe gauge/meter operation minimizing the risk of additional radiation exposure to the gauge operator. 13 Finally, pull the gauge in the direction of the keypad to ensure the source rod is snug against the sidewall of the pilot hole.
15 Return and properly secure gauge/meter in appropriate approved type “A” shipping container. 16. Directly after finishing the test the operator must dig up a 6” X 6” hole to look for cobbles, boulders, organics, or voids. If moisture needs to be checked, put material in a sealed zip lock bag or sealed bottle.
Topic H: Seaman Nuclear Gauge Operation and Procedures
Topic H: Seaman Nuclear Gauge Operation and Procedures H-1 Operation of Seaman Nuclear Density Gauges Three Seaman nuclear density moisture gauges models are used on WisDOT projects. These are: C-75, C-200, and C-300. All three Seaman models are designed to evaluate the density and moisture in soils, crushed aggregate base, asphaltic concrete and other materials. Radioactive Source and Detectors All radioactive materials used in the models C-75, C-200, and C-300 gauges are doubly encapsulated in sealed source capsules(s), and mounted in a shielding mechanism in the bottom center of the gauges. There are two different source configurations available for Seaman gauges. The configuration used in any particular gauge is indicated on the serial label. The two configurations are: Model C-75, C-200, C-300 Source Configurations Isotope
Quantity
Output
Cs 137
8 mCi
gamma
Am241:Be
40 mCi
neutron
4.5 mCi
gamma & neutron
or Ra226:Be
Licensing A license to possess and use nuclear gauges is issued once an application that documents certain specified procedures, and your commitment to follow them, has been approved. Regulatory authorities perform routine compliance inspections to insure that the license requirements that the licensee (you) are following the specified procedures. In the United States, nuclear gauges are regulated either by US Nuclear Regulatory Commission (US NRC) or by States. In most areas of Wisconsin, the State Department of Health Services (DHS) regulates nuclear gauges. The US NRC has jurisdiction in the following areas within Wisconsin: Federal lands, Military bases, and Indian Tribal lands. Wisconsin is an agreement state.
Topic H: Seaman Nuclear Gauge Operation and Procedures H-2 Licensing (continued) A Wisconsin licensee may work on lands under US NRC jurisdiction after reciprocity is applied for and granted. If the work will exceed 180 days per calendar year, a NRC license must be obtained. Internal Components of Models Seaman C-200 and C-300 Gauges A gamma detecting density tube is mounted to the base of the gauge on the left side. A thermal neutron detecting moisture tube is mounted to the base on the right side. The Seaman C-200 is capable of the backscatter mode only. The C-300 is available with an optional direct transmission probe.
Air Gap Ratio Density Determinations for C-200 and C-300 The model 200 gauges use the air gap backscatter method of density measurement; that is, the density is determined by the ratio of the air gap count to the contact count. The contact count is taken with the base of the gauge resting on the surface of the test material. The air gap is taken over the same location with the gauge raised 1 3/4 (45mm) above the surface. This is done by rotating the handle 180 degrees.
Direct Transmission (optional for the C-300) The Seaman Nuclear C-300 moisture/density gauge can be equipped with a probe and accessories for direct transmission (DT) density measurements in addition to the Air Gap Ratio method which is standard on all Seaman Nuclear gauges. The standard probe allows 4 in to 8 in (10 cm to 20 cm) depths and a 4 in to 12 in (10 cm to 30 cm) is also available. The direct transmission method requires the user to create an access hole at the test site to allow a probe containing a gamma measuring detector to be inserted to the desired depth of measure. Radiation passes from the source through the test material to the detector in the probe. The radiation measured by the detector is inversely proportional to density. The test result provides an average density from the bottom of the probe to the surface.
Topic H: Seaman Nuclear Gauge Operation and Procedures H-3 Direct Transmission (optional for the C-300) (continued) When using the direct transmission mode, density is determined from the ratio of the test count (with the probe in the access hole) to the standard count, taken on the reference stand. This standard count is taken each day. Moisture counts are always taken in the surface or backscatter mode, regardless of the density mode being used (air gap backscatter (surface) or direct transmission). In other words, the moisture is not measured with the probe. Air Gap Ratio Density Determination for Seaman C-75 The model 75 gauges use the air gap backscatter method of density measurement; that is, the density is determined by the ratio of the air gap count to the contact count. The contact count is taken with the base of the gauge resting on the
surface of the test material. The air gap is taken over the same location with the gauge raised 1 ½” (38mm) above the surface by the air gap stand. Air Gap Backscatter Theory and Background The gauge is placed on the test surface and the material under the test is exposed to gamma radiation from the radioactive source. The Geiger-Mueller detector inside measures the amount of gamma radiation reflected, or “scattered back” from the material in terms of counts per minute (CPM). The gamma rays induced by the gauges are influenced by the density and the chemical elements, which are part of the material being tested. The density and chemical elements of the material affect the absorption and reflection of the gamma rays. Some combinations of elements vary widely in their absorption, which may cause a significant error in testing. Therefore, the contact backscatter reading is accompanied by an air gap test on the same test location.
Topic H: Seaman Nuclear Gauge Operation and Procedures H-4 Air Gap Backscatter Theory and Background (continued) Additional benefits of the air gap method entail:
Corrects for chemical composition differences between materials. Corrects for counting error due to temperature extremes (e.g., obtain accurate densities behind paver). Correct for background radiation.
WisDOT requires the air gap stand test procedure to be performed as part of every test. Moisture Measurement The moisture determinations are based on the neutron moderation principle to detect the amount of hydrogen present. When testing construction materials, it is assumed the hydrogen detected is in the form of free water (H2O). The radioactive source in the gauge emits high speed neutrons. The neutrons have the same atomic weight as a hydrogen atom. When the high speed neutrons encounter hydrogen atoms in the test material (hydrogen being the element that most effectively slows neutrons), the resulting collisions reduce the speed of the neutrons. The moisture detector in the gauge is sensitive only to slow speed neutrons. Therefore, the greater the moisture count recorded, the greater the amount of (moisture) present.
ASTM D 2950 (WisDOT Modified)
1 of 3
Density of Bituminous Concrete in Place by Seaman Nuclear Methods
Significance and Use This test is used as a rapid nondestructive technique for determining the in-place density of compacted asphaltic concrete mixtures. The nondestructive technique utilizes the backscatter method along with gamma and neutron radiation to determine density and moisture on surface only.
1 Unsecure and unlock properly approved shipping container and nuclear gauge/ meter.
4 Enter “Time/Test” of 120 seconds.
a) Touch the numbers in sequence 120 and observe the display. b) Touch “2nd F” and “F” will be displayed. 2 nd F
PRESS English
2 Turn meter on.
Conduct 10 minute warm-up procedure. Equipment
c) Touch “Enter Time/Test” and “r” will be displayed.
1. Seaman C 75
Time/Test
2. Air Gap Stand 3. Seaman Standard Count Reference 4. Bill of Lading Materials
8
7
Enter
3 Determine
random sampling method for using method ASTM D 3665 to locate test area.
“ R” is Disp
Display
5
Obtain maximum lab density value from project engineer and enter into gauge/meter. a) Enter the lab density in pounds per cubic foot (PCF) or (Kg/m3) by pressing the numbers on the keyboard in sequence. b) Press the “2nd F” key. An “F” will appear. 2 nd F
PRESS English
ASTM D 2950 (WisDOT Modified) Density of Bituminous Concrete in Place by Seaman Nuclear Methods
c) Press the “Enter Lab Density” key. The number in the display will be stored in memory. An “r” will then appear in the display.
2 of 3
11
Put the source in the operating position.
8
d) If you would like to verify the lab density entry, press the “2nd F” key and then the “Display Lab Density” key.
Touch “Start Test” and “C” (contact test) will be displayed. “CF” will be displayed when the count is completed. Practice ALARA by keeping a distance of 1 (one) meter from nuclear gauge/meter during the test. Start Test
6
Position the meter on a randomly selected flat part of the asphaltic concrete surface to be tested. Press the opposite meter corners to verify the meter is stable on a flat surface. This practice will reduce the risk of low-density measurements caused by cracking in the rolling and compaction operations. Mark out complete base of gauge with paint or crayon. C-75 model
PRESS Tem p
9
12
Touch “Start Test” and “A” will be displayed. “AF” will be displayed when the air gap is completed. All test data is now entered into the computer.
Retract the source.
Start Test
PRESS Temp
13
Record the following data on the worksheet.
10
Lift the meter up and place the air gap stand on the test area; place the meter on the air gap stand.
a) Touch contact; the contact reading CPM will be displayed.
Contact
Direction of Source
Mark gauge outline. Use arrow to point in direction of source.
7. Lift source rod handle, rotate counter clockwise, and engage source rod into operating position.
PRESS
Count
Air Gap
in
ASTM D 2950 (WisDOT Modified) Density of Bituminous Concrete in Place by Seaman Nuclear Method
b) Touch “2nd F”, “F” will be displayed, then touch air gap for air gap reading.
2 nd F
PRESS English
c) Touch the “Bulk Density”
Bulk
PRESS
Density
Dry
for density in PCF. d) Touch the percent “% Bulk Density” for the percent of design density.
PRESS
% Bulk Density
% Dry
14
Secure gauge/meter and return to proper storage container.
3 of 3
1 of 4
AASHTO T 239/238 (WisDOT modified) Moisture/Density of In-Place Soil-Aggregate by Seaman Nuclear Methods
Significance and Use This test is used as a rapid nondestructive technique for determining the moisture/density of in-place soil-aggregate mixtures. The nondestructive technique utilizes the backscatter method along with gamma and neutron radiation to determine density and moisture on surface only, respectively.
1 Unsecure and unlock properly approved shipping container and nuclear gauge/ meter.
a) Touch the numbers in sequence 120 and observe the display. b) Touch “2nd F” and “F” will be displayed.
2 nd F
2 Turn meter on for 10 minute warmup. The serial number will appear in display.
Equipment 1. Seaman C75 or C200 2. Air Gap Stand (use only for Model C75) 3. Seaman Standard Count Reference 4. Bill of Lading Materials 5. Field Surface Plate 6. Tile Space or equivalent 7. No. 40 Sieve 8. Hand trowel 9. Draw knife or metal straight edge 10. Knee Pads 11. Appropriate safety apparel
4 Enter “Time/Test” of 120 seconds.
PRESS English
c) Touch “Enter Time/Test” and “r” will be displayed.
Time/Test 8
7
Enter
3 Determine random sampling method for using method ASTM D 3665 to locate test area(s).
“ R” is Dis
Display
5 Obtain maximum proctor moisture/density value from project engineer and enter into gauge/meter. a)
Enter maximum proctor moisture/density value in pounds per cubic foot (PCF) or (Kg/m3) by pressing the numbers on the keyboard in sequence.
b)
Press the “2nd F” key. An “F” will appear. 2 nd F
PRESS English
AASHTO T 239/238 (WisDOT modified)
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Moisture/Density of In-Place Soil-Aggregate by Seaman Nuclear Methods
c) Press the “Enter Lab Density” key. The number in the display will be stored in memory. An “r” will then appear in the display. Lab Density 4
Enter
7 Prepare a horizontal area sufficient in size to accommodate the gauge, by planing the area to a smooth condition so as to obtain maximum contact between the gauge and material being tested.
9 Once a flat test area has been achieved, seat the gauge on the test location and check to ensure bottom of gauge is clean of any debris.
5
Display
d) If you would like to verify the lab density entry, press the “2nd F” key and then the “Display Lab Density” key.
6 Use a tile spade or equivalent to remove all loose and disturbed material as necessary to expose a flat surface to be tested. Note: removing the top surface will ensure a representative moisture will also be tested.
8 The maximum void beneath the gauge shall not exceed 1/8 inch (3mm) and the total area filled beneath the gauge should not exceed 10 percent. Use native fines to fill these voids and then smooth the surface with a rigid plate or other suitable tool.
Note: The placement of the gauge on a flat surface of material to be tested is critical to the actual moisture/density determination.
10 Check opposite gauge corners to ensure that the prepared surface is flat.
3 of 4
AASHTO T 239/238 (WisDOT modified) Moisture/Density of In-Place Soil-Aggregate by Seaman Nuclear Methods
11 Lift source rod handle, rotate counter clockwise, and engage source rod into operating position.
14 Lift the meter up and place the air gap stand on the exact contact test location and place gauge on air gap stand.
17
Retract the source.
18 Touch “Contact Count”, the contact reading will be displayed. Contact
12 Press the “Start Test” key. A “C” will appear in the display, indicating a contact test is in progress. A “CF” will appear when the test is finished.
Count
15 Lift source rod handle, rotate counter clockwise, and engage source rod into operating position.
Air Gap
19 Touch “2nd F” and an “F” will be displayed; touch “Air Gap Count” for air gap reading.
Start Test
PRESS Temp
Note: Always practice ALARA by stepping back a distance of 1 meter during gauge operation. 13
Retract the source.
16 Touch “Start Test” and “A” will be displayed. “AF” will be displayed when the air gap is completed. All test data is now entered into the computer. Start Test
PRESS Temp
2
nd
F
English
Contact Count
Air Gap
AASHTO T 239/238 (WisDOT modified) Moisture/Density of In-Place Soil-Aggregate by Seaman Nuclear Methods
20 Touch “Bulk Density” for wet density in PCF (or kg/m3).
25 Touch “2nd F”, then “% Moisture” to obtain percent of moisture.
Bulk
PRESS
RESS
RESS
Density
Dry
MOISTURE Count Density Std.
22 Touch “Moisture” and the moisture in PCF (or kg/m3) will be displayed. MOISTURE
% MOIST
23 Touch “2nd F”, then touch “Dry Density”, and you will learn the dry density in PCF MOISTURE
PRESS English
% MOIST
(or kg/m3). 2 nd F
PRESS English
MOISTURE
English
% MOIST
PRESS
21 Touch “Moisture Count”; the moisture CPM reading will be displayed.
2 nd F
2 nd F
% Bulk Density
% Dry
24 Touch “2nd F”, then “% Dry Density”, to obtain the percent of proctor density.
26 Once the test is completed, the operator must dig up the center of the gauge foot print, an approximately 6” X 6” area. Check for large cobbles, and boulders, and organics. I f this situation exists, discard test and add a new random test location Retest. 27 Return and properly secure gauge/meter in appropriate approved type “A” shipping container
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Topic I: Emergency Procedures for Nuclear Gauge Operation
TOPIC I: Emergency Procedures
Page I-1
INCIDENTS An incident may be defined as an event where the gauge is lost, stolen, or physically damaged to the extent that the source shielding is or could be compromised.
Topic J: Random Sampling Procedures
TOPIC J: Random Sampling Procedures
Page J-1
Random Sampling The use of a random sampling practice is specified with the intention of eliminating bias in the sample selection process and thus increasing the representative state of samples. Greater reliability is assigned to test results from this process and the strength of data is improved for statistical purposes. The standard method recommended for selecting random sample is ASTM Method D 3665, “Standard Practice for Random Sampling of Construction Materials.” Random numbers may be selected by following the instructions of the method by using a calculator with a random number generator or other commonly accepted methods of selecting random numbers. The selection of random sampling points should be done by the contractor QC personnel. In order to fully ensure the selection of samples is random, only those who need the information (i.e., QC personnel) should be notified. The operator(s) SHALL NOT be advised in advance as to when samples are to be taken. The effectiveness of process control sampling is completely reliant on unbiased sampling and testing. Collusion between the QC personnel and plant operator(s), in this regard, may be cause for DECERTIFICATION of technicians.
TOPIC J: Random Sampling Procedures
Page J-2
One Method for Statistical Sampling A typical random numbers chart follows on the next two pages. Here is how you use it to select a random number. A.
The area under the bell curve, the normal distribution curve is segmented into 1000 equal pieces. Each of these areas are represented by a 3 digit decimal number. The first number is .001, the 23rd number is .023, the 552nd number is .552, etc., and the last number is 1.000.
B.
The chart is printed on two pages. You may combine them on one sheet for convenience. It is a good practice to alternate pages. Use the page on the left then the page on the right. For the next number use the page on the right then the page on the left. (You select these numbers by simply pointing at them with your fingers or a pencil, with your eyes shut.
C.
Point at a number. Write down the first number you’ve selected. Assume it is 0.272. This is the first number in the chart. Point again. Use the second half of the chart on the right. Write down the second number you’ve selected. Assume it is 0.119. This is the last number in the chart.
D.
Lets call the rows of numbers that go up and down the chart “lines”. There are 100 lines. Use the first two digits of our first number, 0.272 which are 2 and 7 or 27. This identifies line 27. Lets call the rows of numbers that go across the chart “columns”. There are 10 columns. Use the first digit of our second number, 0.119, which is 1. This identifies the first column. Our random number is 0.680 The key thought to remember when using this method for statistical sampling is “It takes two numbers to get one number.”
E.
There are nine exceptions to this procedure. Those exceptions are .001, .002, .003, .004, .005, .006, .007, .008, and .009. (The number 0.000 is not in the chart). In the event that one of these numbers is selected in the pointing process, disregard that number and point at another.
Student Question: What happens if you select 1.000 in the pointing process? Answer: Use line 100.
TOPIC J: Random Sampling Procedures
Page J-3
This material is made a part of this training to explain in detail one acceptable method for statistical sampling. This doesn’t replace the AASHTO Standards (i.e. T-2, etc.) or the ASTM standards (i.e. D-3665, etc.) that are referenced in those AASHTO Standards. This is the HTCPs interpretation of those standards. You can get your own copy of the AASHTO Standards at: American Association of State Highway & Transportation Officials 444 N. Capitol Street, N.W. Suite 249 Washington, DC 20001 (202) 624-5800 www.transportation.org
TOPIC J: Random Sampling Procedures
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1 2 3 4 5
0 0.272 0.994 0.039 0.144 0.312
1 0.519 0.978 0.449 0.695 0.138
2 0.098 0.693 0.737 0.339 0.670
CHART OF RANDOM NUMBERS 3 4 5 6 0.459 1.000 0.554 0.250 0.593 0.690 0.028 0.831 0.501 0.960 0.254 0.239 0.621 0.128 0.032 0.413 0.894 0.682 0.061 0.832
7 0.246 0.319 0.474 0.617 0.765
8 0.736 0.073 0.031 0.764 0.226
9 0.432 0.268 0.720 0.257 0.745
6 7 8 9 10
0.871 0.783 0.358 0.494 0.642
0.838 0.874 0.424 0.839 0.514
0.595 0.795 0.684 0.337 0.297
0.576 0.430 0.074 0.325 0.869
0.096 0.265 0.109 0.699 0.744
0.581 0.059 0.345 0.083 0.824
0.245 0.260 0.618 0.043 0.524
0.786 0.563 0.176 0.809 0.656
0.412 0.632 0.352 0.981 0.608
0.867 0.394 0.748 0.499 0.408
11 12 13 14 15
0.485 0.728 0.029 0.918 0.641
0.240 0.819 0.262 0.348 0.013
0.292 0.557 0.558 0.311 0.780
0.335 0.050 0.159 0.232 0.478
0.088 0.152 0.767 0.797 0.529
0.589 0.816 0.175 0.921 0.520
0.127 0.404 0.979 0.995 0.093
0.396 0.079 0.521 0.225 0.426
0.401 0.703 0.781 0.397 0.323
0.407 0.493 0.843 0.356 0.504
16 17 18 19 20
0.208 0.346 0.900 0.228 0.746
0.468 0.429 0.206 0.369 0.170
0.045 0.537 0.539 0.513 0.974
0.798 0.469 0.308 0.762 0.306
0.065 0.697 0.480 0.952 0.145
0.315 0.124 0.293 0.856 0.139
0.318 0.541 0.448 0.574 0.417
0.742 0.525 0.010 0.158 0.195
0.597 0.281 0.836 0.689 0.338
0.080 0.962 0.233 0.579 0.901
21 22 23 24 25
0.363 0.663 0.545 0.360 0.789
0.103 0.942 0.185 0.349 0.815
0.931 0.278 0.054 0.569 0.464
0.389 0.785 0.198 0.910 0.484
0.199 0.638 0.717 0.420 0.020
0.488 0.002 0.247 0.492 0.007
0.915 0.989 0.913 0.947 0.547
0.067 0.462 0.975 0.115 0.941
0.878 0.927 0.555 0.884 0.365
0.640 0.186 0.559 0.452 0.261
26 27 28 29 30
0.279 0.680 0.078 0.676 0.861
0.609 0.235 0.444 0.830 0.899
0.086 0.706 0.178 0.531 0.643
0.852 0.827 0.651 0.888 0.771
0.890 0.572 0.423 0.305 0.037
0.108 0.769 0.672 0.421 0.241
0.076 0.310 0.517 0.307 0.582
0.089 0.036 0.660 0.502 0.578
0.662 0.329 0.657 0.112 0.634
0.607 0.477 0.972 0.808 0.077
31 32 33 34 35
0.111 0.289 0.961 0.637 0.834
0.364 0.857 0.893 0.986 0.121
0.970 0.948 0.392 0.753 0.255
0.669 0.980 0.377 0.566 0.453
0.548 0.132 0.864 0.213 0.376
0.687 0.094 0.472 0.807 0.583
0.639 0.298 0.009 0.017 0.422
0.510 0.870 0.946 0.460 0.371
0.105 0.309 0.766 0.515 0.399
0.549 0.441 0.287 0.630 0.366
36 37 38 39 40
0.284 0.038 0.351 0.143 0.512
0.490 0.814 0.283 0.384 0.056
0.402 0.594 0.027 0.645 0.018
0.151 0.911 0.220 0.479 0.122
0.044 0.324 0.685 0.489 0.303
0.436 0.322 0.527 0.052 0.803
0.747 0.895 0.943 0.187 0.553
0.694 0.411 0.556 0.990 0.729
0.136 0.160 0.853 0.912 0.205
0.585 0.367 0.612 0.750 0.925
41 42 43 44 45
0.296 0.451 0.837 0.724 0.665
0.705 0.536 0.405 0.153 0.825
0.156 0.768 0.591 0.841 0.671
0.616 0.518 0.370 0.829 0.623
0.534 0.481 0.104 0.470 0.770
0.168 0.880 0.848 0.391 0.400
0.564 0.835 0.004 0.388 0.068
0.866 0.734 0.414 0.163 0.440
0.739 0.427 0.354 0.817 0.019
0.850 0.847 0.707 0.790 0.944
46 47 48 49 50
0.573 0.332 0.755 0.439 0.700
0.716 0.702 0.951 0.491 0.877
0.266 0.300 0.937 0.855 0.442
0.456 0.570 0.550 0.446 0.286
0.434 0.945 0.879 0.773 0.526
0.467 0.968 0.162 0.542 0.071
0.603 0.649 0.791 0.416 0.154
0.169 0.097 0.810 0.350 0.988
0.721 0.118 0.625 0.957 0.333
0.779 0.242 0.674 0.419 0.626
TOPIC J: Random Sampling Procedures
Page J-5
CHART OF RANDOM NUMBERS Continued 51 52 53 54 55
0 0.523 0.905 0.373 0.057 0.967
1 0.613 0.182 0.120 0.953 0.040
2 0.752 0.567 0.602 0.041 0.708
3 0.733 0.249 0.793 0.090 0.271
4 0.528 0.227 0.692 0.223 0.189
5 0.072 0.229 0.863 0.508 0.342
6 0.820 0.604 0.954 0.806 0.740
7 0.929 0.304 0.873 0.438 0.801
8 0.777 0.217 0.107 0.203 0.985
9 0.461 0.142 0.675 0.586 0.263
56 57 58 59 60
0.917 0.131 0.326 0.299 0.101
0.715 0.646 0.605 0.106 0.055
0.758 0.659 0.443 0.237 0.776
0.005 0.047 0.601 0.732 0.686
0.666 0.051 0.386 0.796 0.171
0.599 0.562 0.560 0.476 0.533
0.934 0.435 0.378 0.099 0.936
0.100 0.731 0.172 0.804 0.095
0.987 0.362 0.445 0.735 0.982
0.085 0.317 0.636 0.950 0.211
61 62 63 64 65
0.267 0.471 0.535 0.277 0.719
0.598 0.102 0.881 0.458 0.167
0.754 0.454 0.014 0.295 0.181
0.658 0.568 0.966 0.196 0.653
0.274 0.963 0.958 0.772 0.328
0.215 0.357 0.190 0.148 0.070
0.177 0.882 0.180 0.466 0.015
0.218 0.507 0.759 0.291 0.155
0.330 0.157 0.433 0.688 0.631
0.628 0.580 0.355 0.046 0.063
66 67 68 69 70
0.385 0.862 0.486 0.091 0.146
0.858 0.928 0.938 0.872 0.482
0.713 0.822 0.757 0.959 0.930
0.883 0.812 0.749 0.922 0.611
0.916 0.977 0.991 0.727 0.179
0.084 0.395 0.219 0.811 0.011
0.561 0.788 0.264 0.075 0.248
0.999 0.920 0.932 0.374 0.886
0.379 0.673 0.898 0.133 0.344
0.668 0.698 0.006 0.730 0.926
71 72 73 74 75
0.709 0.996 0.971 0.202 0.212
0.184 0.896 0.859 0.538 0.321
0.390 0.760 0.147 0.026 0.778
0.409 0.347 0.114 0.949 0.940
0.191 0.053 0.418 0.696 0.496
0.117 0.372 0.889 0.008 0.231
0.860 0.193 0.792 0.846 0.664
0.135 0.756 0.064 0.259 0.903
0.406 0.565 0.652 0.415 0.473
0.134 0.914 0.288 0.425 0.909
76 77 78 79 80
0.207 0.818 0.701 0.035 0.221
0.799 0.503 0.984 0.380 0.200
0.487 0.906 0.174 0.001 0.587
0.022 0.224 0.141 0.381 0.353
0.813 0.904 0.704 0.251 0.584
0.891 0.892 0.908 0.497 0.270
0.500 0.455 0.048 0.214 0.885
0.368 0.343 0.828 0.794 0.110
0.725 0.924 0.997 0.552 0.956
0.437 0.197 0.058 0.588 0.711
81 82 83 84 85
0.647 0.667 0.644 0.302 0.633
0.403 0.722 0.590 0.123 0.933
0.530 0.327 0.021 0.116 0.331
0.738 0.723 0.269 0.282 0.546
0.280 0.410 0.042 0.851 0.842
0.457 0.635 0.062 0.256 0.016
0.650 0.012 0.387 0.648 0.236
0.276 0.907 0.183 0.845 0.164
0.661 0.316 0.964 0.782 0.923
0.973 0.677 0.544 0.993 0.976
86 87 88 89 90
0.060 0.165 0.875 0.726 0.273
0.681 0.532 0.691 0.902 0.393
0.683 0.431 0.383 0.252 0.285
0.775 0.341 0.382 0.130 0.161
0.624 0.092 0.596 0.238 0.619
0.955 0.244 0.301 0.398 0.865
0.126 0.222 0.275 0.763 0.551
0.655 0.336 0.188 0.463 0.030
0.919 0.034 0.868 0.615 0.571
0.113 0.216 0.805 0.140 0.258
91 92 93 94 95
0.253 0.340 0.194 0.166 0.712
0.821 0.654 0.290 0.450 0.314
0.600 0.173 0.592 0.210 0.033
0.023 0.495 0.983 0.204 0.823
0.606 0.498 0.509 0.840 0.629
0.849 0.992 0.998 0.826 0.939
0.610 0.192 0.522 0.833 0.887
0.577 0.506 0.627 0.516 0.066
0.082 0.751 0.741 0.965 0.743
0.774 0.129 0.540 0.375 0.081
96 97 98 99 100
0.622 0.313 0.137 0.243 0.361
0.800 0.294 0.087 0.679 0.359
0.710 0.897 0.003 0.844 0.230
0.575 0.718 0.483 0.069 0.761
0.678 0.614 0.201 0.024 0.334
0.465 0.876 0.209 0.543 0.149
0.802 0.025 0.320 0.714 0.511
0.969 0.049 0.935 0.234 0.475
0.150 0.620 0.447 0.505 0.854
0.784 0.125 0.787 0.428 0.119
TOPIC J: Random Sampling Procedures
Page J-6
Random Number Determination Random numbers should be selected using the ASTM D 3665 Standard Practice for Random Sampling of Construction Materials, the chart provided, or by a calculator random number generator.
Sublot A B C D E
Offset No. 1 2 3 4
1st Random No. 0.950 0.702 0.864 0.643 0.326
2nd Random No. 0.603 0.449 0.893 0.393 0.671
Line No.
1st Random No. 0.110 0.999 0.661 0.502
2nd Random No. 0.879 0.701 0.026 0.188
Line No.
95 70 86 64 32
11 99 66 50
Column No.
Random No.
6 4 8 3 6
0.877 0.179 0.919 0.196 0.298
Column No.
Random No.
8 7 0 1
0.401 0.234 0.385 0.877
TOPIC J: Random Sampling Procedures
Page J-7
QMP HMA Pavement Nuclear Density – Linear Sublots & Daily Lots Step 1: Starting from the beginning station of the project, divide each lane into sublots using the specified sublot length. The only sublot that should have a partial length is the last sublot at the end of the project limits. Step 2: Using the table in the specification, determine the number of tests required in each sublot, depending on the lane width. Step 3: Determine one random test station in each sublot. The sublot random test station is computed by multiplying the length of the sublot by a random number, and adding the result to the beginning station of the sublot. Step 4: Determine the stations for each test site. For a sublot requiring only one test site, the test station will be the random station computed in step 3. For a sublot requiring multiple test sites, the first test will be taken at the station computed in step 3, with each subsequent test being performed 10 feet up station from the previous test. Step 5: Determine the testing offset width and offset ranges for each lane. The offset width is the lane width divided by the number of required tests in the sublot. Step 6: Determine the test site offsets. A random transverse location must be computed for each test site by multiplying the offset width by a random number, and adding the result to the beginning of the corresponding offset range.
Sublot Length (1500’ Typ) C Test 1 B
Offset Width
Test 2
Offset Range 2
A Test 3 10’
10’
Sample Sublot
Offset Range 1
Offset Range 3
Lane Width
TOPIC J: Random Sampling Procedures
Page J-8
Example Project Information:
Divide total distance by 1500. If the last sublot in the lane or shoulder is equal to or greater than 750 feet, = or > 750’, it will become a mini-sublot. If less than750’, < 750”, this last sublot will be incorporated in the last prior sublot. If you project has a equation or a bridge that length needs to be taken out of the sublot and your sublot will be separated into two different parts. A project begins at station 56+78 and ends at station 131+78. It is a 2-lane roadway with a shoulder on each side. The traffic lanes are 12 feet wide and the shoulders are 3 feet wide. Shown in the diagram below is the eastbound traffic lane and shoulder for the length of the project. The contractor will be paving the shoulder integrally with the traffic lane. The pavement is a 2-inch overlay and the same HMA mix type is used on the entire project. From the QMP Specifications we determined the following Required sub lot length is 1500 lineal feet
Determine Random Sublot Test Locations
Test No. A B C D E
1 Beginning Station
3+1=2 2 End Station
Lot Length
56+78 71+78 86+78 101+78 116+78
71+78 86+78 101+78 116+78 131+78
1500’ 1500’ 1500’ 1500’ 1500’
3
4 Random Number x x x x x
0.887 0.179 0.919 0.196 0.298
= = = = =
3x4=5 5 Distance from Beginning 13+31 2+69 13+79 2+94 4+47
5+1=6 6 Test Station 70+09 74+47 100+57 104+72 121+25
Determine Random Test Offsets for Sublot A 3 Random mainline offset tests are required per the specifications at the following equal intervals 0-4’, 4-8’, 8-12’ and one shoulder test is required per specifications in the offset range of 12-15’.
Offset from Centerline Sub Lot A
G
Sub Lot Test No. 1 2 3 1
Offset Range 0-4’ 4-8’ 8-12’ 12-15’
Offset Width 4’ 4’ 4’ 3’
x x x x
Random No. 0.401 0.234 0.385 0.877
= = = =
Random Offset 2’ 1’ 2’ 3’
Test Offset + Beginning of Offset Range = Test Offset 0’ + 2’ = 2’ 4’ + 1’ = 5’ 8’ + 2’ = 10’ 12’ + 3’ = 15’
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TOPIC J: Random Sampling Procedures
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The random test locations were determined in the table on the page J-9. Note that since the shoulder was paved integrally, the shoulder was included in the same table and each shoulder test station was a continuation of the adjacent traffic lane. The shoulder is considered a separate lane and sublot due to the different density requirements. If the shoulder was paved in a separate pass, a different random station would need to be computed. Day 1: The contractor begins paving at station 56+78 and ends the day at station 102+97. A quantity of 677 tons was placed on the eastbound traffic lane, and 169 tons was placed on the integral shoulder. Day 2: The contractor begins paving at station 102+97. Due to traffic staging requirements, the contractor stops paving at station 159+93 and begins paving again at station 202+36. They end the day at the end of the project, station 234+25. A quantity of 1303 tons was paved on the eastbound traffic lane, and 326 tons was placed on the integral shoulder. Day 3: The contractor begins paving at station 159+93 and ends the day at station 202+36. A total of 622 tons was placed on the eastbound traffic lane, and 156 tons was placed on the integral shoulder.
56+78
159+93
102+97 Day 1
Day 2
A
B
C
1
4
7
2
5 3
37
M
8 6
38
7 8
O
E
F
G
H
I
J
K
L
16
19
22
25
28
31
34
14
12 40
17
15 41
P
Day 2
Day 3
13
11 9
39
N
D 10
234+25
202+36
18 42
Q
20 21 43
R
23 24 44
S
26
T
Example Project Sublots & Lots
29
27 45
30 46
U
32 33 47
V
35
W
36 48
X
TOPIC J: Random Sampling Procedures
Page J-16
Example Problem #1: Use the example project information and the following test results from day 1. All of the day’s air voids tests were acceptable. Sublot I.D. A
B
C
M N O
Test I.D. 1 2 3 4 5 6 7 8 9 37 38 39
% Density
Sublot Avg % Density
92.8 93.2 93.4 93.1 93.7 93.6 92.6 93.5 93.3 91.7 92.7 91.5
1)
Compute the average density for each traffic lane sublot and each shoulder sublot.
2)
Compute the density incentive or disincentive for the day’s paving.
TOPIC J: Random Sampling Procedures
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Example Problem #1 SOLUTION: Use the example project information and the following test results from day 1. All of the day’s air voids tests were acceptable. Sublot I.D. A
B
C
M N O 1)
Test I.D. 1 2 3 4 5 6 7 8 9 37 38 39
% Density 92.8 93.2 93.4 93.1 93.7 93.6 92.6 93.5 93.3 91.7 92.7 91.5
Sublot Avg % Density 93.1
93.5
93.1
91.7 92.7 91.5
Compute the average density for each traffic lane sublot and each shoulder sublot. SOLUTION: See the results in the table above.
2)
Compute the density incentive or disincentive for the day’s paving. SOLUTION: Traffic Lane: The minimum required density is 92.0%. All of the sublot averages were no more than one percent below the required minimum density, so all of the day’s traffic lane test results are used to compute the lot density and the lot incentive pay. Lot density = (92.8 + 93.2 + 93.4 + 93.1 + 93.7 + 93.6 + 92.6 + 93.5 + 93.3) = 93.2% 9 tests According to the specification, this lot density is eligible for incentive pay of $0.40 per ton. 677 tons of HMA was placed on the traffic lane on day 1, therefore the contractor receives $270.80 density incentive for that lot. Shoulder: The minimum required density is 90.5%. All of the sublot averages were acceptable, so all of the day’s shoulder tests are used to compute the shoulder lot density. The average of all the shoulder tests is 92.0%. According to the specification, this lot density is eligible for incentive pay of $0.40 per ton. 169 tons of HMA was placed on the shoulder on day 1, therefore the contractor receives $67.60 density incentive for that lot.
TOPIC J: Random Sampling Procedures
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Example Problem #2: Use the example project information and the following test results from day 3. All of the day’s air voids tests were acceptable. Sublot I.D. H
Test I.D. 22 23 24 25 26 27 28 29 30 44 45 46
I
J
T U V
% Density
Sublot Avg % Density 90.8
90.8 90.9 90.7 94.1 93.8 93.9 91.0 90.8 90.9 90.4 92.9 90.6
93.9
90.9
90.4 92.9 90.6
Compute the density incentive or disincentive for the day’s paving.
56+78
159+93
102+97 Day 1
Day 2
A
B
C
1
4
7
2
5 3
37
M
8 6
38
7 8
O
E
F
G
H
I
J
K
L
16
19
22
25
28
31
34
14
12 40
17
15 41
P
Day 2
Day 3
13
11 9
39
N
D 10
234+25
202+36
18 42
Q
20 21 43
R
23 24 44
S
26
T
Example Project Sublots & Lots
29
27 45
30 46
U
32 33 47
V
35
W
36 48
X
TOPIC J: Random Sampling Procedures
Page J-19
Example Problem #2 SOLUTION: Use the example project information and the following test results from day 3. All of the day’s air voids tests were acceptable. Sublot I.D. H
I
J
T U V
Test I.D. 22 23 24 25 26 27 28 29 30 44 45 46
% Density 90.8 90.9 90.7 94.1 93.8 93.9 91.0 90.8 90.9 90.4 92.9 90.6
Sublot Avg % Density 90.8
93.9
90.9
90.4 92.9 90.6
Compute the density incentive or disincentive for the day’s paving. SOLUTION: Traffic Lane: According to the specification, a minimum density of 92% is required for the traffic lane. When verifying whether or not the sublot densities meet the requirements, it is found that sublot H and sublot J have average densities that are more than one percent below the required minimum. According to the specification, the quantities of HMA pavement and asphaltic material items placed this day in each of these sublots is subject to disincentive, and the day’s test results within these sublots are not included when computing the incentive for the remainder of the lot. Sublot H: Day 3 began inside the limits of sublot G, but beyond its random test location. The tests for sublot G represent material placed on day 2. The tests in sublot H represent the day 3 material from station 159+93 to 176+78, a total area of 1685 feet long and 12 feet wide. Quantity represented by tests in sublot H = (1685’ x 12’) x (2 in. x 110 lb/sy/in) = 247 tons (9 sf/sy) (2000 lb/ton) Quantity of asphaltic material = (0.055 x 247 tons) = 13.6 tons According to the disincentive pay table in the specification, the quantities are subject to a pay factor equal to 95 percent of the contract price. This is equivalent to a 5 percent pay reduction. Disincentive Density HMA Pavement = 247 tons x ($28/ton x 0.05) = -$345.80 Disincentive Density Asphaltic Material = 13.6 tons x ($250/ton x 0.05) = -$170.00
TOPIC J: Random Sampling Procedures
Page J-20
Sublot I: Quantity represented by tests in sublot I = (1500’ x 12’) x (2 in. x 110 lb/sy/in) = 220 tons (9 sf/sy) (2000 lb/ton) According to the incentive pay table, 220 tons of the HMA pavement item are eligible for an incentive of $0.80 per ton, or a total of $176.00. Sublot J: Day 3 ended within the limits of sublot J, beyond its random test location. The day 3 quantity placed within sublot J, from station 191+78 to 202+36, is represented by its tests. The day 2 quantity placed toward the end of sublot J is represented by the tests taken on day 2 within sublot K. Quantity represented by tests in sublot J = (1058’ x 12’) x (2 in. x 110 lb/sy/in) = 155 tons (9 sf/sy) (2000 lb/ton) Quantity of asphaltic material = (0.055 x 155 tons) = 8.5 tons According to the disincentive pay table in the specification, the quantities are subject to a pay factor equal to 95 percent of the contract price. This is equivalent to a 5 percent pay reduction. Disincentive Density HMA Pavement = 155 tons x ($28/ton x 0.05) = -$217.00 Disincentive Density Asphaltic Material = 8.5 tons x ($250/ton x 0.05) = -$106.25 Shoulder: All of the day 3 shoulder sublots have acceptable density values, so we use all of the results to compute the day’s shoulder lot density. Day 3 shoulder lot density = (90.4 + 92.9 + 90.6) = 91.3% 3 tests The lot density of 91.3% is not more than 1.0% above the required minimum of 90.5%, therefore the day 3 shoulder pavement does not receive any density incentive.
Day 3 Incentive/Disincentive Summary: Incentive Density HMA Pavement = $176.00 Disincentive Density HMA Pavement = (-$345.80) + (-$217.00) = -$562.80 Disincentive Density Asphaltic Material = (-$170.00) + (-$106.25) = -$276.25
TOPIC J: Random Sampling Procedures
Page J-21
Accuracy of Density Test Measurement Should an established test site location be within one foot of a restricted edge of the asphaltic concrete pavement, move the test site location inward to a point one foot from the edge. If the established test site occurs on a structure, move the test site to the nearest point about fifteen (15) feet from the structure, but at the same transverse offset. While the intent is to perform all testing at the locations determined, it is not intended that an inordinate amount of time be spent taping; therefore, ±three (3) feet in the longitudinally or ±one (1) foot transversely is acceptable. Some test site adjustment may be necessary if slight surface irregularities are present. All individual density test computations shall be to the nearest 0.1 percent compaction. The test values for each lot shall be averaged and reported to the nearest 0.1 percent compaction.
Center of Gauge
Curb and Gutter 1.5’
1’
First pass of HMA
Unrestricted Edge
Restricted Edge
1RT is considered an Unrestricted Edge Move Gauge in 1.5’
12’ Lane of HMA with Michigan joint sealed
First Pass of the12’ lane of HMA with a Michigan Joint
1 Left
1LT is considered a Restricted Edge move gauge in 1’
1 Right
TOPIC J: Random Sampling Procedures
Page J-22
Sub Lot Tonnage Calculation
NOMINAL INCH LIFTS
LANE WIDTH
0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 5.25 5.50 5.75 6.00
2
3
4
5
6
7
9 14 18 23 28 32 37 41 46 50 55 60 64 69 73 78 83 87 92 96 101 105 110
14 21 28 34 41 48 55 62 69 76 83 89 96 103 110 117 124 131 138 144 151 158 165
18 28 37 46 55 64 73 83 92 101 110 119 128 138 147 156 165 174 183 193 202 211 220
23 34 46 57 69 80 92 103 115 126 138 149 160 172 183 195 206 218 229 241 252 264 275
28 41 55 69 83 96 110 124 138 151 165 179 193 206 220 234 248 261 275 289 303 316 330
32 48 64 80 96 112 128 144 160 176 193 209 225 241 257 273 289 305 321 337 353 369 385
Sublot Length Determination =
1500 FEET SUBLOTS 8 9 10
37 55 73 92 110 128 147 165 183 202 220 238 257 275 293 312 330 348 367 385 403 422 440
41 62 83 103 124 144 165 186 206 227 248 268 289 309 330 351 371 392 413 433 454 474 495
Feet X Width X 110 X Depth 9 x 2000
46 69 92 115 138 160 183 206 229 252 275 298 321 344 367 390 413 435 458 481 504 527 550
11
12
13
14
15
16
50 76 101 126 151 176 202 227 252 277 303 328 353 378 403 429 454 479 504 529 555 580 605
55 83 110 138 165 193 220 248 275 303 330 358 385 413 440 468 495 523 550 578 605 633 660
60 89 119 149 179 209 238 268 298 328 358 387 417 447 477 506 536 566 596 626 655 685 715
64 96 128 160 193 225 257 289 321 353 385 417 449 481 513 545 578 610 642 674 706 738 770
69 103 138 172 206 241 275 309 344 378 413 447 481 516 550 584 619 653 688 722 756 791 825
73 110 147 183 220 257 293 330 367 403 440 477 513 550 587 623 660 697 733 770 807 843 880
Topic K: Nuclear Gauge Policy for Operation on WisDOT Projects
Wisconsin Department of Transportation Division of Transportation System Development Bureau of Technical Services Truax Center 3502 Kinsman Blvd. Madison, WI 53704-2507
DATE:
January 1, 2017
TO:
Consultant and Contractor Working For WisDOT
FROM:
Barry Paye Chief Quality Management Engineer
SUBJECT:
Nuclear Gauge Policy for Operation on WisDOT Projects Acceptance and QMP Density Testing
Telephone: (608) 246-3246 Facsimile (FAX): (608) 246-4669
In the year 2016 construction season, all nuclear density testing for improvement projects and all acceptance testing and sampling is required to be done by certified technicians. Certified samplers and testers is a FHWA requirement of CFR 23 part 637. Only the University of Wisconsin Platteville as part of the Highway Technician Certification Program (HTCP) offers the Nucdensitytec-I class. Attached you will find policy information for the operation of ALL nuclear gauges on WisDOT administered projects, including WisDOT, consultant and contractor gauges. WisDOT has established a list of consultants and contractors gauges approved to perform nuclear testing on WisDOT administered projects. Consultants and contractors gauges must be on this list in order to perform nuclear gauge testing on WisDOT projects for the season. This list is established and will be maintained by the Quality Assurance Unit in central office and will be accessible to all WisDOT projects. This information is available on the WisDOT approved products web site at http://www.dot.wisconsin.gov/business/engrserv/approvedprod.htm. To verify that we have the correct information for your company, you are required to submit the following information yearly: 1. Current copy of your Wisconsin Agreement State License or Your Federal Nuclear Regulatory Commission (NRC) license and copy of your Reciprocity. 2. Copies of current 3 or 5 block calibration certificates conducted by manufacturer or calibration service for each gauge. 3. Company contact person, RSO or Safety Officer, (please update as changes occur). E mail address and cellular phone number if applicable. 4. Copies of the WisDOT block calibration test results for each gauge. The test blocks are located at 2841 Industrial Street, Wisconsin Rapids, WI 54495. To schedule an appointment please contact Mike Bohn 608-516-6359 or email at
[email protected]
Please send this information to:
[email protected] Wisconsin Department of Transportation ATTN: WisDOT RSO 2841 Industrial Street Wisconsin Rapids, WI 54495
DT91
Solving tomorrow’s transportation challenges
Please contact the region Materials Section if you have any questions regarding the following information. If further assistance is needed, contact Mike Bohn, WisDOT Radiation Safety Officer, at (608) 516-6359 Cellular. OPERATION OF NUCLEAR GAUGES ON WisDOT PROJECTS To comply with DHS and Federal regulations, protect the safety of operators and the public, and maintain acceptable accuracy of measurement, all gauge operators will be required to comply with all DHS and WisDOT directives, rules and policies pertaining to nuclear testing operations. Such compliance will include, but not be limited to, the following items: 1. When an accident including a lost or stolen gauge, stuck source, damaged gauge or a gauge involved in a vehicle accident occurs, follow your emergency procedures including contacting the Radiation Safety Officer. 2. All accidents involving nuclear density gauges must be reported to the WisDOT RSO at (608) 243-5998 (work) or (608) 516-6359 (cell) and DHS at (608) 267-4797, during daytime hours or the 24 emergency number at (608) 258-0099. When using the 24-hour emergency number indicate this is a “radiological incident.” 3. For the reporting requirements see DHS 157.13(17) (b) 2 and DHS 157.32(1).
4. Authorized User Training will satisfy your license requirements. 5. Transportation of gauges will be in an approved, properly labeled and locked transport Type “A” case. A shipper Declaration of Dangerous Goods or a bill of lading will be properly displayed. When the gauge is not directly under direct supervision, the gauge must be locked in its transport case and protected by two separate physical barriers. 6. Evidence will be provided to ascertain that gauges maintain acceptable levels of calibration. All gauges used on WisDOT projects will have a documented three or five block calibration conducted by the manufacturer or calibration service within the last 12 months. 7. Storage of nuclear gauges will meet both WisDOT and DHS requirements. 8. All operators will wear an appropriate personally issued Thermo Luminescent Dosimeter or Film Badge, or OSL badge per DHS 157.25(2) (a) 6. “NOTE” The operator need not wear a badge if their DHS Radioactive Materials License or NRC license excludes the use of testers using badges.
9. All companies must have available an appropriate radiation survey meter in accordance with DHS 157.05(3).
10. Survey meter must be calibrated annually by a licensed calibration facility. 11. All accidents or incidents involving nuclear gauges will be resolved in accordance with individual license requirements and/or with WisDOT and DHS policies and procedures. 12. Periodic review of nuclear density gauge operation and procedures will be conducted by WisDOT RSO, deficiencies will be discussed with the operator(s) and the operator(s) will take corrective actions. 13. The duration of density tests will be four (4) minutes for Troxler, CPN, Humboldt gauges and two (2) minutes in both the contact and the air gap position for Seaman gauges for quality assurance.
USE OF NUCLEAR GAUGES ON HMA 1. It is highly recommended that moisture density gauge used on WisDOT projects be checked out on WisDOT regional reference check blocks to ascertain their calibration is within 1.0 pound per cubic foot of our block values. Gauges will be warmed up if required in the manufacturer’s guidelines. The regions have the ability to require gauges to be checked on their reference blocks prior to working on WisDOT projects.
2. The region and contractor will establish a reference site approved by both the department and contractor. Clearly marked out on a flat surface of concrete or asphalt or other material that will not be disturbed. Perform correlation monitoring with the QC, QV, and all back up gauges at the project reference site. 3. Conduct an initial 10 density tests using the gauge on the project reference site, and calculate the average value to establish the reference value for each gauge. Use the gauge reference value as a control to monitor the calibration of the gauge for the duration of the project. 4. Check the gauge on the project reference site a minimum of 1 test per day if paving. 5. If a single gauge reading on the reference site deviates more than 1.5 lb/ft 3 from the 10-test average for that gauge. The operator must investigate and conduct an additional 5 tests on the reference site. If the gauge does not fall within allowable tolerances contact WisDOT RSO and region contact person immediately. 6. On days that the QC, QA, or QV tester is performing tests for the project he or she must take a new standard count on the material being tested. 7. During testing, the gauge will always be set on a flat and level surface on the material being tested. A new standard must be taken on the grade before testing.
8. During tests, the following minimum distances of a gauge will be maintained a) b) c) d) e) f) g)
Pavement construction joints > 20 feet Operator > 3 feet Bystanders > 15 feet Equipment, manholes, etc.> 15 feet Other nuclear devices > 30 feet Unrestricted edge of pavement > 1.5 feet Restricted edge of pavement > 1 foot
9. During testing, the gauge will always be set on a flat surface, with the longest dimension of the gauge parallel to the edge of the pavement. Mark out gauge outline and show direction of source. 10. The duration of density tests will be four (4) minutes for Troxler, CPN, Humboldt gauges and two (2) minutes in both the contact and the air gap position for Seaman gauges for quality assurance. 11. Record on the pavement the lot number, test #, and the % compaction for all acceptance and verification tests. Documentation: The following data will be recorded using WisDOT data work sheets.
Standard Block Data – Density Standard, Moisture Standard New Density & Moisture Standard Must Be Taken Every Day There Is Placement Of HMA Material That Requires Density Testing. Density Count, Moisture Counts or Contact, Air Gap Total / Wet Density or Bulk Density % Compaction Manufacture Name and Serial Number Operators Name Mix Design Number and Target Number (Gmm) X 62.24
USE OF NUCLEAR GAUGES ON SOILS, BASE COURSES, ETC. 1. It is highly recommended that moisture density gauge used on WisDOT projects be checked out on WisDOT regional reference check blocks to ascertain their calibration is within 1.0 pound per cubic foot of our block values. Gauges will be warmed up if required in the manufacturer’s guidelines. 2. The region and contractor will establish a project reference site approved by both the department and the contractor. Clearly marked out on a flat surface of concrete or asphalt or other material that will not be disturbed during the duration of the project. Perform correlation monitoring with the QC and QV, and all back up gauges at the project reference site. 3. Conduct an initial 10 density tests using a gauge on the project reference site and calculate the average value to establish a reference value. Use the reference value as a control to monitor the calibration of the gauge for the duration of the project. 4. Check the gauge on the project reference site a minimum of 1 test per day during placement of all material placed within the 1 to 1 slopes on project and compare to the reference value. Maintain the reference site test data for each gauge at an agreed location. 5. If a single gauge reading on the reference site deviates more than 1.5 lb/ft 3 from the 10-test average for that gauge. The operator must investigate and conduct an additional 5 tests on the reference site. If the gauge does not fall within allowable tolerances contact WisDOT RSO and Region contact person immediately. 6. If the department supplies a ValiDator II for the established project reference site conduct an initial 5 density tests at the depth that will be tested in the field. Use the gauge reference value as a control to monitor the calibration of the gauge for the duration of the project. Check each gauge on the project ValiDator II a minimum of one test per day at each testing location during placement of materials on the project. Calculate the difference between the gauge’s daily test result and its reference value. Investigate if a daily test result is not within 1.0 lb/ft3 of its reference value. Conduct 5 additional tests at the reference site once the cause of deviation is corrected. Calculate and record the average of the 5 additional tests. Remove the gauge from the project if the 5-test average is not within 1.0lb/ft3 of its reference value. 7. On days that the QC, QA, or QV tester is performing tests for the project he or she must take a new standard count on the material being tested. 8. During tests, the following minimum distances of a gauge will be maintained from: a) b) c) d)
Operator > 3 feet Bystanders > 15 feet minimum Equipment, manholes, etc.> 15 feet Other nuclear gauges > 30 feet
9. The gauge will be placed on a prepared surface with no mote the 1/16” void and only native material used as filler. 10. Position the gauge handle to the appropriate test location in either BS, 2”, 4”, 6”or 8” depth. Test will not exceed the depth of the compacted layer. 11. After each test the operator must dig up the material below the gauge and check for voids, cobbles and or organics that could change test results. 12. The duration of density tests will be four (4) minutes for Troxler, CPN, Humboldt and Seaman gauges with direct transmission. For Seaman gauges using backscatter the duration will be (2) minutes in both the contact and the air gap position. 13. If the gauge needs to have a moisture biases for a specific soils the gauge operators needs to conduct 2 random test locations for that soils type. After each moisture/density gauge test has been completed the material directly below the gauge will be retained and a 1 point proctors will be run at its natural moisture. Compare average natural moistures to the gauge moisture reading and if necessary compute moisture bias. 14. All proctor tests will have a minimum of 4 or 5 points 2 ascending and 2 descending and 1 at or near the optimum the moisture curve. Documentation: The following data must be recorded on all WisDOT project data work sheets:
Standard Block Data – Density Standard, Moisture Standard Density Count, Moisture Counts or Contact, Air Gap Total / Wet Density or Bulk Density Dry Density or Bulk Density Dry Moisture # and Moisture % Proctor Number and Target Number Pit Number, Grading area, Soils Classifications, Elevation % Compaction Manufacture Name and Serial Number Operators Name
Topic L: Nuclear Density Worksheets
The new updated forms for testing with moisture/density gauges on WisDOT projects are now available on the intranet for the district to print at http://dotnet/forms/frDTIDHC.htm The municipalities, contractors, consultants, and others can obtain and print their copies of these forms from the intranet at www.dot.wisconsin.gov/forms/index.htm
Insert Daily Reference log here.
Appendix 1: CMM 8.15 , AASHTO Test Numbers, Lab Exam
Construction and Materials Manual Chapter 8 Section 15
Wisconsin Department of Transportation
Materials Testing, Sampling, Acceptance Density Testing
Materials sampling and testing methods and documentation procedures prescribed in chapter 8 of the CMM are mobilized into the contract per standard spec 106.3.4.1 and standard spec 106.3.4.3.1. CMM provisions mobilized by the contract: CMM 8-15.10.2.1, CMM 8-15.10.2.2, CMM 8-15.10.2.3
Note: CMM 8-15 Exhibit 1 provides density testing guidance for combined bid contracts. 8-15.1 General Field densities are taken by nuclear methods in accordance with established procedures as required by the contract. If the contract contains quality management program (QMP) density testing provisions, the contractor performs quality control density testing and the department performs quality verification density testing. If the contract doesn’t include QMP density testing provisions, the department will perform all density testing per standard spec 460.3.3.2. Once a method has been selected for determining mat density; that method should be used throughout the project. 8-15.2 Nuclear Gauges The State of Wisconsin Department of Health Services (DHS), Radiation Protection Section issues a license to WisDOT specifying that use of radioactive gauges by the department be supervised by the WisDOT Radiation Safety Officer (RSO). The RSO must be kept informed of the location and usage activities of WisDOT nuclear gauges at all times. The WisDOT RSO contact information will be supplied to each user of a WisDOT nuclear density gauge. The WisDOT RSO may be contacted at the following telephone numbers: (608) 516-6359, Primary (715) 421-8002, Wisconsin Rapids Office Nuclear gauge owners are responsible for compliance with State of Wisconsin DHS Radioactive Materials license or NRC license requirements. In addition, they must comply with WisDOT requirements when engaged in work on WisDOT projects. Personnel who either use nuclear gauges or directly supervise the use of gauges must be trained in radiation safety and transportation of radioactive materials, and must maintain the appropriate Highway Technician Certification Program (HTCP) certifications. Sampling and testing certification is an FHWA requirement in the CFR 23 part 637. The Nucdensitytec-1 class is offered only by the University of Wisconsin Platteville as part of the HTCP. For certification class schedules contact the director of the HTCP at (608) 342-1545 or http://www.uwplatt.edu/htcp/
In addition to certification of the operator, the department requires that all individual nuclear moisture / density gauges used on WisDOT projects be on the approved list. This policy applies to all WisDOT, consultant, and contractor gauges used for acceptance or QMP density testing. Before each construction season, the gauge must be calibrated by a manufacturer approved calibration service provider, and then the tester must perform calibration adjustments for each gauge using the reference blocks located in the Wisconsin Rapids Sign Shop, 2841 Industrial Street, Wisconsin Rapids, WI. This procedure must be followed if the gauge is sent in for any manufacturer calibration or service during the construction season. Contact the RSO at the numbers listed above for access to the blocks and scheduling. WisDOT maintains an annual list of consultants and contractors certified gauges approved to perform nuclear testing on WisDOT administered projects. Consultants and contractors must be on this list in order to perform acceptance and nuclear gauge testing on WisDOT projects. This list is established and maintained by the Quality Assurance Unit in central office, and is available at: http://wisconsindot.gov/Pages/doing-bus/eng-consultants/cnslt-rsrces/tools/appr-prod/default.aspx
To verify that the department has the correct information for your company, you must submit the following information yearly: 1. Current copy of your Wisconsin Agreement State License or your Federal Nuclear Regulatory Commission (NRC) license. 2. Copies of current nuclear moisture and density gauge 3 block calibration certificates (5 blocks for other states) conducted by the manufacturer or an approved calibration service. 3. Company contact person, RSO, or safety officer (please update as changes occur). 4. The WisDOT Block Calibration form,(including new constants), WS7011.
Please send this information to: Wisconsin Department of Transportation March 2016
Page 1
CMM 8-15 Density Testing Bureau of Technical Services, Truax Center ATTN: WisDOT RSO 3502 Kinsman Blvd Madison WI 53704-2507
[email protected] (Note: email is to be used as the primary means of sending this information)
Testing of some soils, fly ash, and coarse materials requiring special testing procedures, for which the operator will need additional training. Contact the WisDOT RSO for further information regarding special testing procedures. 8-15.3 Nuclear Density Gauge Safety 8-15.3.1 Lost or Stolen Gauges If a gauge is lost or stolen, notify the Radiation Safety Officer (RSO) as soon as possible. The RSO will notify the appropriate regulatory agency per DHS 157. 8-15.3.2 Damaged Gauges The operator will follow these procedures in the event of gauge damage (per DHS 157 Appendix H). All companies must have available an appropriate radiation survey meter in accordance with http://docs.legis.wisconsin.gov/code/admin_code/dhs/110/157.pdf - Seal off the area for a distance of 15 feet around the gauge in question to prevent exposure to themselves and others. Protect the gauge from further damage. - Stop the vehicle or heavy piece of equipment that is involved, it must be detained in order to verify that it is not contaminated. - Never let the gauge in question be left UNATTENDED. - Visually inspect the gauge to determine the extent of the damage to the source(s), source housing(s), and shielding. Check the base of the gauge for any splits or punctures. Take Pictures, take notes and statements to document incident. - Do not handle the gauge if it has been damaged severely enough that source rod or internal shielding is cracked or broken open. - Notify the Radiation Safety Officer (or notify supervisor who will contact the RSO) as soon as possible. The RSO will notify the appropriate regulatory agency. - Follow the instructions of the RSO
8-15.4 Annual Bureau of Technical Services Gauge Block Calibration Procedures Run both the Block and ValiDator procedures for each gauge as described below: 1. Bureau of Technical Services Block Procedure - Maintain 30’ or greater spacing between gauges. - Sweep off yellow, red, and green blocks. - Perform manufacturer recommended warm up time if applicable. Gauges should only be used when they stabilize to ambient room temperature. - Place the manufactures supplied poly standard block on the yellow concrete block and perform the Standard Count, and record data on department supplied block forms. - Remove the poly standard block and align the front of the gauge that it touches the front line on the yellow block, and center the gauge. - Take a four minute back-scatter (BS) test for CPN, Troxler, Humbolt and InstroTek gauges, or a two minute test for both Contact and Air gap for Seaman nuclear gauges. - Without moving the handle for CPN, Troxler, Humbolt, or InstroTek, record the required data Wet pcf, # Moisture, Density counts, and Moisture counts and then perform the next test. - For Seaman gauges record the required data Wet PCF, # Moisture, Density counts, Moisture counts. Recenter the gauge and perform the next test. - Take three tests for each concrete test block and record the data for each test. DO NOT perform a new standard for each block.
March 2016
Page 2
CMM 8-15 Density Testing 2. ValiDator Procedure - Perform BS Scatter and Direct Transmission (DT) tests on the ValiDator. - Place gauge up against the stops on the side and front of the ValiDator. Use the same procedures as described in the block procedure section when testing in Backscatter (BS) mode. Take three tests and record the data, do not perform a new standard. - For the DT test procedure on the ValiDator, pull the trigger and lower the gauge probe down to 4 inches, make sure that the probe is locked and in the proper position by raising the handle slightly above the 4 inch location. Check with the palm of your hand and push down until it stops. - Once in the proper depth location for the DT gauges, pull the gauge to the rear of the ValiDator and make firm contact with the materials housed within the unit. Take three tests and record the data, do not perform a new standard. - Take a test at 6 inches on the ValiDator, make sure that the probe is locked in at the proper position by raising the handle slightly above the 6” location and with the palm of your hand push down until it stops. - Once in the proper depth location for the DT gauges, pull the gauge to the rear of the ValiDator and make firm contact with the materials housed within the unit. Take three tests and record the data, (do not perform a new standard).
Record both the Block and ValiDator results on the WisDOT Block Calibration form WS7011 and submit to the RSO. 8-15.5 Nuclear Density Testing HMA 8-15.5.1 General Take necessary steps to coordinate and schedule the required nuclear test equipment and a trained operator so the required density testing may be performed expeditiously within the specified time requirements. All density testing must be done as soon as practical after the completion of the compaction process and before opening to traffic. On a closed road testing must be completed before the end of the next working day after placement. Gauges must be in the shielded position and locked when not in use. Gauges should never be left unattended when in use. During tests, the gauge must be kept the following minimum distances from: - Pavement transverse construction joints ................... 20 feet - Bridge deck expansion joints ..................................... 20 feet - Operator ..................................................................... 3 feet - Bystanders ................................................................. 15 feet - Equipment, manholes, etc. ........................................ 15 feet - Other nuclear devices ................................................ 30 feet - Unrestricted edge of pavement.................................. 1.5 feet - Restricted edge of pavement ..................................... 1 foot Gauges must be warmed up and checked following the manufacturer’s guidelines. 8-15.6 Project Nuclear Density Testing The operator will take new standard counts for density and moisture at the project. (Note: it is important to check the standard counts daily to account for changing conditions and to check gauge performance. An incorrect moisture count will cause a gauge to incorrectly determine density. This check should be done daily on all manufacturers’ gauges (Troxler, CPN, Humbolt, Seaman and so forth). 8-15.7 QMP QC & QV Nuclear Density Gauge Correlations Select a representative section of the compacted HMA pavement prior to or on the first day of paving for the correlation process. The section does not have to be the same mix design. Correlate the 2 or more gauges used for density measurements (QC, QV). The QC and QV gauge operators will perform the correlation on 5 test sites jointly determined. Record each density measurement of each test site for the QC, QV and other acceptance gauges. Calculate the average of the difference in density between the QC and QV gauges of the 5 test sites. Locate an additional 5 test sites if the average difference exceeds 1.0 lb/ft3. Measure and record the density on the 5 additional test sites for each gauge if applicable. Calculate the average of the difference in density between the QC and QV gauges of the 10 test sites. If the average difference of the 10 tests exceeds 1 lb/ft3, the regional HMA Coordinator will use their gauge to investigate the situation with the QC and QV personnel, with the consultation of the RSO, to determine necessary actions. If calibration factors need to be adjusted in the field, contact the RSO beforehand for guidance and documentation. On Soils, Sand & Gravel, Recycled Materials, Stabilized Bases, etc, select a representative section of the compacted material prior to or on the first day of placement for the correlation process. Correlate the 2 or more gauges used for QC and QV density measurements in BS or in DT mode. The QC and QV gauge operators will perform the correlation on 5 test sites jointly located. Record each density measurement of each test site for the QC, QV and other acceptance gauges. Calculate the average of the difference in dry density between the QC March 2016
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CMM 8-15 Density Testing
and QV gauges of the 5 test sites. If the average dry density difference exceeds 1.5 lb/ft3, locate an additional 5 test sites. Measure and record the density on the 5 additional test sites for each gauge if applicable. Calculate the average of the difference in dry density between the QC and QV gauges of the 10 test sites. If the average difference of the 10 tests exceed 1.5 lb.ft3, replace one or more gauges and repeat the correlation process. Use the last two test sites from the final correlation process and proceed with your moisture basis calculations as explained in CMM 8-15.12.1. If the difference in moisture content between a gauge and the corresponding sample exceeds 1.0 lb/ft3, then a moisture bias needs to be calculated for that gauge for the specific soil classification. The bias needs to be checked during placement or if the material classification changes. If testing in DT mode, operators need to be cautious to ensure that the pilot holes do not collapse. Provide one of the QC or QV gauges that passed the correlation process, within allowable tolerances, to perform density testing on the project. 8-15.8 HMA QMP Reference Site Monitoring After performing the gauge correlation on HMA, establish a project reference site approved by the department. Clearly mark a flat surface of concrete or asphalt or other material that will not be disturbed for the duration of the project. Perform reference site monitoring of the QC, QV, and any additional gauges at the project reference site. Conduct an initial 10 density tests with each gauge on the project reference site and calculate the average value for each gauge to establish the gauge’s reference value. Use the gauge’s reference value as a control to monitor the calibration of the gauge for the duration of the project. Check each gauge on the project reference site at least once a day, before performing any density testing. Calculate the difference between the gauge’s daily test result and its reference value. Investigate if a daily test result is not within 1.5 lb/ft3 of its reference value. Conduct 5 additional tests at the reference site once the cause of the deviation is corrected. Calculate and record the average of the 5 additional tests. Remove the gauge from the project if the 5 test average is not within 1.5 lb/ft3 of its reference value. The regional HMA coordinator will use their gauge to investigate these situations with the QC and QV personnel to determine necessary actions. 8-15.9 Non QMP HMA Nuclear Density Reference Site Monitoring For non QMP HMA Nuclear Density projects, the regional block can be used as the project reference site. Each gauge needs to be within 1 lb/ft3 of the block’s reference value. If the region chooses to use a project located reference site, use the procedure explained in CMM 8-15.8. 8-15.10 Use of Nuclear Moisture/Density Gauges on HMA During testing, the gauge must always be set on a flat level surface on the material being tested, with the longest dimension of the gauge positioned parallel to the edge of the pavement. Outline the gauge with a lumber crayon or paint stick and show the direction of the source. Record the sub-lot number, percent compaction and density in lbs/ft3 on the pavement for all acceptance and verification tests. Check the gauge on the reference site at least once a day if a new density or moisture standard is established, and before performing any moisture or density tests. The designated materials persons (standard spec 106.1.2) will determine how the documentation will be communicated at the preconstruction meeting. A new density and moisture standard must be established daily during paving operations of new HMA pavements that require density testing. A new standard is also required if testing different materials on the same day (e.g., testing aggregate base and then switching to HMA testing). Changing the HMA mix type, or base course material sources does not require a new standard. The following data must be recorded daily on field project data sheets. These sheets will be made available to the project engineer upon request: - Reference site block data - Standard block data, including the density and moisture standard - Density count, moisture counts or contact and air gap counts
8-15.10.1 Target Maximum Density For HMA pavement density determination, the target value in lb/ft3 is established using the mixture maximum specific gravity (Gmm). On the first day of paving an HMA mixture design, the target maximum density will be the Gmm value indicated on the mix design multiplied by 62.24 lb/ft3 . The target maximum density for all other days will be the Gmm four-test running average from the end of the previous days’ production multiplied by 62.24lb/ft3. If four tests have not been completed by the end of the first day, the average of the completed Gmm test values multiplied by 62.24 lb/ft3 will be used until a four-point running average is established. The following data must be recorded for each test on the worksheet for MRS entry March 2016
Density standard and moisture standard Density count, moisture counts or contact and air gap counts Total wet density or bulk density % Compaction Page 4
CMM 8-15 Density Testing - Manufacturer name and serial number - Operators name - Mix design number (WisDOT 250 ID) and daily Target max density target number (Gmm x 62.24 lb/ft3)
8-15.10.2 Determining Test Locations There are two different systems for determining locations for nuclear density testing. The linear system is to be used on all paving projects, including mainline paving, shoulders and appurtenances. The nominal tonnage system is to be used in areas where continuous lengths of paving are less than 1500 feet, including side roads, crossovers, turn lanes, ramps and roundabouts. The procedure for using each is described below. 8-15.10.2.1 Determining Test Locations Using Linear Sublots When using the linear sublot testing specification, the sublot locations are to be determined prior to the project start-up for standard, constant width, mainline paving. Segmented, staged work with variable widths may need some adjustment during construction. A sublot is defined as 1,500 lane feet for each layer and target density. The number of required tests within each sublot is dependent on the lane width and is to be determined according to the Table 1 below. A sublot may include more than one day’s paving. It is not required to take an additional non-random test if a sublot spans more than one day’s paving. Examples 3 and 4 demonstrate how to calculate incentive and disincentive in these situations. A partial quantity less than 750 lane feet will be included with the previous sublot at the end of the project. A partial quantity greater than 750 lane feet will be considered a standalone sublot. Table 1 Number of test at each station, as determined by width Lane Width
No. of Tests
Transverse Location
5 ft or less
1
Random
Greater than 5 ft to 9 ft
2
Random within 2 equal widths
Greater than 9 ft
3
Random within 3 equal widths
Here are some basic steps for determining test locations within sublots: Step 1: Starting from the beginning station of the project, divide each lane into sublots using the specified sublot length. The only sublot that should have a partial length is the last sublot at the end of the project limits, although bridges or other paving obstacles may cause partial sublot lengths. Step 2: Using the table in the specification, determine the number of tests required in each sublot, depending on the lane width. Step 3: Determine one random test station in each sublot. The sublot random test station is computed by multiplying the length of the sublot by a random number, and adding the result to the beginning station of the sublot. Step 4: Determine the stations for each test site. For a sublot requiring only one test site, the test station will be the random station computed in step 3. For a sublot requiring multiple test sites, the first test will be taken at the station computed in step 3, with each subsequent test being performed 10 feet up station from the previous test. Step 5: Determine the testing offset width and offset ranges for each lane. The offset width is the lane width divided by the number of required tests in the sublot. Step 6: Determine the test site offsets. A random transverse location must be computed for each test site by multiplying the offset width by a random number, and adding the result to the beginning of the corresponding offset range.
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CMM 8-15 Density Testing Figure 1 Linear Sublot Layout
8-15.10.2.2 Side Roads-Intersections-Crossovers-Turn Lanes-Ramps- Roundabouts (
