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Operation and Maintenance of Pervious Concrete Pavements John T. Kevern (corresponding author), Department of Civil and Mechanical Engineering, University of Missouri-Kansas City, Kansas City, MO 64110, Phone: 816-235-1286, Fax: 816-235-5977, E-mail: [email protected]

November 15, 2010 Text Tables (2) Figures (14) Total Words:

3495 500 3500 7495 (7500 max)

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ABSTRACT While permeable pavements have been applied in limited use in the southeastern United States since the 1970’s, only recently have they become a more wide-spread technology for stormwater management. Various industry groups have done well promoting the benefits of permeable pavements, however maintenance issues are rarely discussed in-depth. Maintenance of permeable pavements involves cleaning to restore permeability and the repair of structural and non-structural deficiencies. This paper discusses common causes and identification of common and not so common pavement distresses for Portland Cement Pervious Concrete. Methods to assess surface condition and permeability are presented along with a discussion using test section results. Suggestions for cleaning and surface repair are provided. This paper is designed to assist with selection of appropriate remediation techniques for individual levels of pervious concrete distresses. (129 words)

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INTRODUCTION AND BACKGROUND Permeable pavements are an increasingly used stormwater best management practice across the U.S. to help meet National Pollutant Discharge System (NPDES) requirements and to control flooding. Generally permeable pavements are grouped into pervious concrete, porous asphalt, interlocking permeable pavers, turf support systems, and various other proprietary systems where either the asphalt or cementitious binders are replaced with some type of adhesive. The obvious benefits include reduced or eliminated stormwater runoff, groundwater recharge, and pollutant removal through filtering and microbial degradation (1). Other recent research has shown that in particular Portland Cement Pervious Concrete (PCPC) has the potential to help mitigate the urban heat island, provide a safer walking surface, and is a very quiet pavement (2, 3, 4). However the primary use for pervious concrete will continue to be for stormwater management in parking areas. This presents a unique challenge to owners since pervious concrete systems are both pavements and stormwater filters, requiring two areas for maintenance considerations. Due to the high permeability, typical pavement maintenance such as crack sealing and pothole filling are not appropriate for pervious concrete. Routine cleaning is required to maintain adequate permeability for the stormwater design. The research in PCPC has been mostly driven by questions raised through active promotion of the product. Research has progressed from mixture proportioning for durable pavements (especially cold weather climates), to construction logistics, to testing, and finally now to maintenance and operation. Mixture proportioning is relatively well-understood with various methods available (5). A balance of aggregate voids and paste achieves the required load-carrying capacity and ability to transmit water. A small portion of sand (~7%) is required for cold weather durability (6, 7). Construction practices have become somewhat standardized with the creation of the National Ready Mixed Concrete Association (NRMCA) Pervious Concrete Contractor Certification Program (8). While manual placement techniques are currently most common, various manufacturers have begun producing mechanized placement equipment (9). Recognizing a need for standardized testing techniques, an ASTM committee C09.49 was formed for pervious concrete. To date two standards, ASTM C1688 for fresh unit weight and ASTM C1701 for field permeability, have been released with numerous others under development (10, 11). Promotion and research have created a demand, developed durable materials, and refined placement techniques allowing a large number of placements in recent years. However, the area of maintenance is lacking in information because of the short amount of time most placements have been in service compared with the ultimate design lives. This paper presents the current common maintenance techniques and proposed remediation techniques for future use. Maintenance is divided into that for permeability and that for the pavement serviceability. An example of surface characterization and permeability requirements are provided for an example test parking lot. Proper understanding of the maintenance requirements for pervious concrete will allow these placements to function correctly for many years. CONSIDERATIONS FOR SUCCESSFUL LONG TERM INSTALLATIONS Through the experiences of many owners, municipalities, industry organizations, researchers, producers, and contractors, good documents are available to provide guidance for design and construction of pervious concrete placements. The following is an abbreviated list of key suggestions for successful pervious concrete installation compiled from information available by

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ACI 522 committee, NRMCA contractor training course, Concrete Promotion Group of Kansas City, and the Design of Pervious Concrete Mixtures (5, 8, 12, 13).  While pervious concrete mixtures contain the same materials as traditional concrete (i.e. cement, water, sand, and rock), a balance between cementitious paste, aggregate gradation, and material volumes must be achieved to create a durable and permeable mixture. The low water-to-cement ratio and high internal friction during mixing require higher quality admixtures to achieve workability longevity. Available guidance for mixture proportioning pervious concrete is available. Although like any concrete mixture guidance, local producers should fine tune mixtures for local materials, environmental conditions, and production facilities.  A contractor experienced with pervious concrete placements is required. The low waterto-cement ratio and high volume of exposed paste surface area results in an evaporation rate much greater than any other type of concrete. Rapid placement with a minimized handling time is required for a durable placement.  The high exposed surface area and irregular surface requires that pervious concrete be cured under plastic sheeting for at least 7-days. The plastic must be applied within 20 minutes of discharging from the ready-mixed concrete truck. In some environmental conditions the amount of time pervious concrete can be exposed may be much less.  Joints should be installed at least one-fourth of the pavement thickness. Joints may be saw-cut or formed. Formed joints should be installed with only one pass of the jointing device as additional passes further open the joint causing deterioration. Saw-cut joints should be created as soon as the material becomes strong enough not to ravel, usually after 24 hours. Care should be taken to minimize the amount of time the surface is exposed to prevent drying.  After the plastic is removed at 7-days, care should be taken to protect the new pavement from damage. Typical early-age damage occurs when heavy vehicle loads are placed on the pavement soon after opening or when other construction trades use the pavement as a staging area. When at all possible pervious concrete placements should be installed very near the end of a project to prevent clogging with construction debris.  Many sites that have become clogged have become so from large amounts of nearby unstabilized soil running onto the pavement during construction. Appropriate erosion control techniques should be in place to prevent loose soil from clogging the surface. PERMEABILITY MAINTENANCE Permeable pavements are filters, filters remove particles from fluids, as more particles are removed the flow rate is reduced and maintenance is required to restore the flow rate. The rate of clogging of a filter is based on the initial permeability and pore size, type and amount of material to be filtered, rate of the fluid carrying the material, and the level of service requiring regeneration of the filter. The controlling aspects are the initial permeability of the pavement, the amount of additional surrounding stormwater designed to infiltrate through the surface, the amount of soil in the stormwater, and the slope of the pavement. With all of these factors, the maintenance required for a permeable pavement is highly site dependent. It has been observed that the permeability of typical pervious concrete placements is maintained with semi-annual cleaning. Clogging most often occurs when unforeseen amounts of soil wash onto the pavement surface during construction. Consequently, permeability maintenance considers both routine cleaning and clogging restoration.

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Research has shown that sand-sized particles are more likely to be retained on the surface, while silt and clay sized particles are more likely to become deposited at the bottom of the aggregate layer. The smaller particles are deposited in a loose state and usually comprised of nearby soil, so permeability and storage of the system is not significantly affected (14, 15). However, as a particle enters the pervious concrete system, the torturous path settles particles near the surface. As more and more particles become filtered out, there is a progressive failure of permeability from the top. Fortunately, then the top layer clogs protecting the middle and bottom of the concrete from clogging. The progressive clogging at the surface is highly desirable because surface cleaning is both relatively easy and effective at restoring lost permeability. Field infiltration rate of pervious concrete, and all hard-surface permeable pavements, is easily determined using ASTM C1701 “Standard Test Method for Infiltration Rate of In Place Pervious Concrete” (11). FIGURE 1 shows the infiltration test, which is a single-ring setup using a constant head methodology. ASTM C1701 can be used to verify desired infiltration rates of specific mix designs, test initial permeability, and test permeability reduction over time. Typically an average infiltration decrease of 25% from the initial value triggers pre-selected maintenance activities. However, ASTM C1701 can also be performed on a case-by-case basis to identify clogged areas or to determine an optimized cleaning pattern.

FIGURE 1 Field Infiltration Testing Using ASTM C1701

The most available experience with permeable pavements and maintenance comes from the asphalt industry and the use of open-graded friction course (OGFC) on highways. NCHRP Report 640 provides recommendations for maintenance of asphalt permeable friction courses (16). Permeability on clogged OGFC sections can be restored using a combination of high pressure water ranging from 860 kPa to 3,450 kPa (125 psi to 500 psi) with a vacuum to remove the debris. Routine maintenance (maintenance performed before clogging occurs) was more effective at maintaining permeability for longer periods of time. Routine maintenance for PCPC can be achieved by standard street cleaning equipment containing a vacuum to remove particles from the surface (17). On smaller installations pressure washing has shown effective, however the width must be such that the particles freed from the surface travel off of the pavement and not clog other sections. Pressure washing is commonly used for permeability maintenance on sidewalks. FIGURE 2 shows routine maintenance on pervious concrete in Olathe, KS. The stripping seen in the picture is from water used for dust control. The typical cleaning speed used for traditional pavement or curb and gutter applications does not allow enough time to completely clean debris from the surface pores. Vehicle speed

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should be reduced by visually evaluating when all of the debris has been removed from a test location.

FIGURE 2 Typical Pavement Cleaning Operations

An unexpected event such as a large rainfall during construction or retaining wall collapse can result in clogging. Research has shown that human observation of clogged areas well-predicts the results from in-situ testing (18). The soil particles must be removed from the surface and typically the top 25 mm (1-inch) of pavement to restore adequate permeability. Clogging is remediated by a combination of wetting the soil particles and vacuuming from the surface. Combinations of pressure-washing and vacuuming have successfully cleaned many pervious concrete placements. High velocity water can damage the surface by removing individual aggregate particles from the surface. Care should be taken not to damage the surface while cleaning. FIGURE 3a shows repair of clogged pavement using a typical street-sweeper used for routine maintenance. The pavement was first prewetted to saturate the soil, the dust control water was increased to maximum flow rate, and the sweeper velocity was reduced to a slow walk. The bottom portion of the picture is cleaned pervious concrete, while water is still ponded on the clogged concrete yet to be cleaned at the top of the picture. FIGURE 3b shows a simple PVC vacuum attachment constructed for use with storm drain cleanout equipment.

a

b

FIGURE 3 Cleaning Operations Modified for Pervious Concrete

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PAVEMENT DISTRESS IDENTIFICATION The second area of operation and maintenance is remediation of physical defects in the pavement. Unlike traditional pavements, a majority of pervious concrete pavement distresses occur at the surface. TABLE 1 lists the variety of typical pavement distresses for pervious concrete pavements. The most common distress is raveling, which is the separation of individual cement-coated aggregate pieces from the pavement surface. Levels of raveling distresses are discussed in TABLE 2. Light raveling occurs when a few poorly-bonded particles become loose immediately after construction (FIGURE 4). The pieces can be swept off the pavement and no additional raveling occurs. Moderate raveling occurs from a weak concrete mixture, from inadequate curing, or from excessive loading after opening. While the pavement may not look ideal, structural capacity has not been compromised. The first action is to clean the pavement and monitor to determine if raveling continues. If raveling continues, then additional remediation may be desired. Depending on the extent of raveling, localized milling or a complete removal and replacement may be performed. Milling of OGFC asphalt is a common strategy to remediate excess raveling (16). Severe raveling occurs for pervious concrete when a majority of the surface particles ravel, typically due to poor curing practices. FIGURE 5 shows an example of severe raveling where loose material was swept away to determine the depth of material loss. Cores should be removed to determine the extent of the deterioration. If only limited to the surface, then the structural capacity is adequate. Remediation can be achieved by milling to competent material, overlaying on the surface or with or without milling, or removal and replacement. Total failure can occur when a combination of: mix design, contractor experience, and/or environmental conditions result in pervious concrete with excessively high voids (~35% or greater). If more than half of the pavement depth ravels, then a complete removal and replacement or structural overlay is required.

FIGURE 4 Light Surface Raveling

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FIGURE 5 Severe Surface Raveling

Joint deterioration occurs as excessive raveling at joint locations. Causes of joint raveling can be sawing too early or multiple passes with a joint-forming device. Each time a joint-forming device passes over fresh pervious concrete a few particles are pulled from the surface and deposited at a new location. These transplanted particles never properly mesh at the new location and ravel. Less manipulation of the fresh concrete results in a more durable surface. FIGURE 6a shows joint deterioration caused by multiple passes with a jointing roller. FIGURE 6b shows a double joint caused by multiple passes with the jointing roller. Before the method of remediation can be determined, the first action is to vacuum the joints and monitor for continued raveling. If raveling continues the joint can be filled, sealed, or a 300mm (12-inch) section can be cut around the joint and replaced with new material.

a

b

FIGURE 6 Joint Deterioration

Cracking can occur when the joint depth is not sufficiently deep enough to cause a shrinkage crack to relieve stresses. The other main cause of cracking is overloading the structural capacity of the pavement. Considerations for additional thickness should be taken when designing a pervious concrete parking area for the path of heavy vehicles such as delivery, garbage, and fire trucks.

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Sealing is a localized area where cement paste blocks the surface pores as shown in FIGURE 7. Sealing may be caused by incorrect mixture proportions or adding water to the pavement surface to prevent drying. Typically sealing does not affect the pavement as stormwater drains to nearby permeable sections. Since sealing does occur at the surface, light milling can restore permeability. Localized coring and replacement with permeable material can also be a method of remediation.

FIGURE 7 Sealed Surface

Material deterioration is a limited, site-specific occurrence not characterized by any of the previously mentioned distresses. Pervious concrete does not have any unique material distresses not experienced with traditional concrete. However the rapid permeability and small thickness of paste surrounding the aggregate suggests typical durability issues such as durability cracking and alkali-silica reaction may be less of a concern with pervious concrete (19). When permeable pavements are used for staging materials and care is not taken to protect the surface, localized abrasion or marring can occur. While not a structural issue, abrasion from fork trucks and other abuse is preventable. FIGURE 8a shows an example of staging landscaping materials on a pervious concrete placement and FIGURE 8b shows some of the damage caused by the end-loader transferring materials and causing marring.

a

b

FIGURE 8 Abrasion from inappropriate construction staging (photos provided by the Indiana Ready Mixed Concrete Association)

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TABLE 1 Pavement Distress Identification Pavement Description Potential Causes Distress Mid-Panel Individual aggregate Inadequate curing, Raveling pieces dislodged Low strength mixture, from the concrete Heavy loading at early surface age Joint Deterioration Raveling at joint Saw cut too early, locations Improper installation of formed joint Cracking Fractures other than Overloading, inadequate at the joints. joint depth Sealing Excess paste on Too much water in pavement surface mixture, reducing or Too much paste in eliminating mixture, infiltration Excess mist water Material Pavement Not durable aggregate, Deterioration deterioration other early-age deicer usage, than raveling dirty aggregate Abrasion Light-colored marks Plowing, equipment on the pavement staging, surface TABLE 2 Raveling Distress Identification Pavement Condition Description 1 - New Smooth, uniform surface 2 – Light Raveling A few loose particles on the surface 3 – Moderate Raveling 25% loss of surface particles with no rutting 4 – Severe Raveling 50% or greater loss of surface particles with localized rutting 5 – Total Failure 100% loss of surface particles with significant rutting

Remediation Strategies See Table 2.

Vacuum and monitor, fill, remove and replace. Monitor, fill, remove and replace. Mill, localized replacement

Monitor, mill, overlay, remove and replace Monitor, mill, remove and replace

Remediation Strategies None required Vacuuming or sweeping to remove particles Vacuuming and monitoring, localized milling, localized removal and replacement Milling, overlay, localized removal and replacement Removal and replacement, structural overlay

FIGURE 9 shows condition survey results from a pervious concrete parking lot containing a wide range of raveling distress levels. This particular installation had been installed 6 years and located at a ready-mixed concrete facility. At the time of installation this was the first pervious concrete section in the region. Generally the construction practices were poor and mixture consistency varied greatly between concrete loads. The bold numbers represent infiltration testing locations. The strips beginning with 1, 25, 37, and 61 from the left were cured under plastic for 7-days, while the in-fill strips were not. The strips not cured under plastic generally had much poorer condition ratings. FIGURE 10 shows the wide range of measured infiltration values. However, the condition rating directly corresponded with the measured infiltration. On this site, as the level of raveling increased, the infiltration rate decreased as the raveled particles filled in the surface voids. The lowest measured infiltration rate was 14 cm/hr (6 in./hr) on a section clogged with construction sediment, while the highest infiltration was 7,170 cm/hr (2,820 in./hr). The average infiltration rate was 2,250 cm/hr (890 in./hr) and the median

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infiltration rate was 1,900 cm/hr (750 in./hr). From the condition survey, sections can easily be identified for distress and permeability remediation.

FIGURE 9 Example Site Condition Survey with Infiltration Testing

Condition 2

7,000 6,000 5,000

1,000 500 0

4,000

Condition 1

1,500

3,000 2,000

Infiltration (cm/hr)

Condition 3

2,000

Condition 4

Infiltration (in./hr)

2,500

8,000

Condition 5

3,000

1,000 0

FIGURE 10 Example Infiltration Survey

WINTER MAINTENANCE In much of the U.S., winter maintenance is required to keep pavement serviceable yearround. Winter maintenance activities include plowing, salting, and sanding. Pervious concrete contains 15% to 25% voids and when snow is plowed from the surface, some snow will remain in the surface pore space. Plow operators should be informed of the difference in pavement types and expected visual look of clean pervious concrete. Otherwise, the operator may continue to clear the surface and cause undue abrasion in the process. FIGURE 11 shows a pervious concrete

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surface after plowing on the left and a traditional concrete surface after plowing on the righthand side.

FIGURE 11 Snow in the Pervious Concrete Surface

Salt is applied to the surface of pavements to create a brine to prevent freezing and ice formation. Sand is often included with the salt to provide traction if the pavement does freeze. The air layer within the pervious concrete slab and within the aggregate base keeps PCPC warmer in cold weather. The stored heat within the system along with the inability to pond melted water, may make pervious concrete a safer pavement (19, 3). However, there are certain instances when salt and sand as still applied to pervious pavements. Because a brine cannot be formed on the surface, more salt will be applied to achieve similar effects. FIGURE 12 shows a traditional concrete pavement which would require salt and sand application and a pervious concrete pavement that would not. Concern should be taken in environmentally sensitive areas to reduce chlorides going directly into the stormwater via the pavement. Sand applied to pervious concrete will become trapped at the surface and reduce some permeability. Depending on the amount of sand applied, vacuuming in the spring will be required to restore permeability. Clean sand is typically applied for traction and is permeable, albeit less than the original pervious concrete surface. Deicer salt scaling on pervious concrete is not a commonly reported distress in cold climates. The low water-to-cement ratio creates a very low permeability paste. The lower permeability and better curing help create a more resistive system to deicing chemicals even when high amounts of blast furnace slag are used. A common distress in cold weather climates is abrasion from snow plows. If panels are not flush, during the first few passes with a plow some abrasion will occur. Plowing should be performed with a wide blade and pervious concrete pavements should not be cleared by backdragging with skid-steer device.

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FIGURE 12 Traditional and Pervious Concretes During Melting

UNANTICIPATED MAINTENANCE Occasionally, even after designing a permeable pavement system using the best available techniques, an area can experience excessive sediment loading leading to wide-spread clogging. Easily clogged areas are often a persistent problem, but issues first arise during or soon after completing construction. Excessive clogging occurs when the amount of suspended solids overwhelms the permeability of the system, either during construction from unstabilized soils or by having inadequate initial permeability. While an infiltration rate of 30 cm/hr (12 in./hr) is theoretically adequate to handle the maximum 25 yr, 24 hr storm event in the U.S., the pore diameter and flow velocity within the pervious concrete would be so small, clogging would occur soon after placing. Again, ASTM C1701 is available for determining the infiltration rate of pervious concrete (11). Pavements with field permeability rates of 1,250 cm/hr (500 in./hr) or greater tested with ASTM C1701 have shown little indication of long-term permeability maintenance concerns, as example of the data shown in FIGURE 10. Permeable pavements constructed on steep slopes can also have inadequate initial permeability. Inadequate permeability occurs when the stormwater sheet flow velocity exceeds the permeability causing a large amount of runoff. Inadequate permeability is more of a concern when large contributing impervious areas are directed towards the pervious pavement. FIGURE 13 shows one instance where a large upstream impervious parking lot developed sheet flow velocities that exceeded the receiving pervious concrete permeability. The result was a large amount of water sheet flowing over the pervious concrete.

FIGURE 13 Velocity and Volume Exceeding Infiltration

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Both excessive clogging and inadequate permeability can be solved by creating distributed areas of high permeability drain sections. These drains can be traditional structures or be areas where lower permeability pervious concrete is replaced with a much higher permeability mixture. FIGURE 14 shows the removal of lower permeability concrete and the installation of a high permeability mixture. Oftentimes replacing a few panels is the most cost effective option to improve a deficient project, since the aggregate base is in place and the stormwater infrastructure for the pervious system is already installed.

a

b

FIGURE 14 Installation of a High Permeability Drain Section

SUMMARY Pervious concrete pavements are becoming a wide-spread technique for stormwater mitigation. However due to the relative newness of the product, limited experiences with maintenance and repair are reported. Since permeable pavements are both pavements and stormwater filters, both require specific maintenance actions. The amount of permeability maintenance is site specific, but generally low when designed correctly and protected from soil run on during construction. The following is a summary of the most common distresses and maintenance considerations presented herein.  Raveling is the most common surface defect and can be minimized using a good concrete mixture and experience contractor with proper curing. Raveling can be remediated by lightly milling the pavement surface followed by a thorough cleaning.  The ASTM C1701 test method for field infiltration rate easily determines the initial infiltration and allows measurement over time for timing of maintenance activities.  A simple surface condition rating of 1 to 5 allows quick determination of the level of distress and correlated well to infiltration rate for the test site in FIGURE 9.  Winter maintenance activities include plowing, salting, and sanding. Pervious concrete pavements can be salted and sanded. Overall less salt is required than traditional pavements, while addition of sand to the surface will require more frequent cleanings. ACKNOWLEDGEMENTS The author would like to thank Geiger Ready Mix and the City of Olathe, KS for allowing access to the pervious concrete sites. Condition survey and permeability testing was performed by students Christopher Farney and Kyle Dunning.

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REFERENCES 1. Tennis, P.D., Leming, M.L., and Akers, D.J. “Pervious Concrete Pavements.” EB302, Portland Cement Association, Skokie, Illinois, and National Ready Mixed Concrete Association, Silver Spring, Maryland, 2004. 2. Kevern, J.T., Haselbach, L., and Schaefer, V.R. “Hot Weather Comparative Heat Balances in Pervious/Impervious Pavement Systems,” Second International Conference on Countermeasures to Urban Heat Islands, Berkeley, CA, 2009. 3. Kevern, J.T., King, G. “NSF EAGER: Improving Pedestrian Safety Using Pervious Concrete to Reduce Slip-Related Falls, $40,000, 2009. (project on-going) 4. Schaefer, V.R., Kevern, J.T., Izevbekhai, B., Wang, K., Cutler, H., and Wiegand, P. “Construction and Performance of the Pervious Concrete Overlay at MnROAD,” Transportation Research Record: Journal of the Transportation Research Board (TRB), Construction, 2010. 5. American Concrete Institute (ACI) Pervious Concrete, “522-R10: ACI 522 Committee Report,” Farmington Hills, MI: ACI, 2010. 6. Schaefer, V.R., Wang, K., Suleiman, M.T., and Kevern, J. Mix Design Development for Pervious Concrete in Cold Weather Climates. A Report from the National Concrete Pavement Technology Center (CP Tech Center), Ames, IA: Iowa State University, 2006. http://www.ctre.iastate.edu/reports/mix_design_pervious.pdf 7. Kevern, J.T., Schaefer, V.R., Wang, K., and Suleiman, M.T. “Pervious Concrete Mixture Proportions for Improved Freeze-Thaw Durability.” Journal of ASTM International, 2008, Vol. 5, No. 2., DOI:10.1520/JAI101320. 8. National Ready Mixed Concrete Association (NRMCA) “Text Reference for Pervious Concrete Contractor Certification.” NRMCA Publication #2PPCRT, Silver Spring, MD, 2005. 9. Kevern, J.T. “Evolution of Portland Cement Pervious Concrete Construction,” Challenges, Opportunities, and Solutions in Structural Engineering and Construction, The Fifth International Structural Engineering and Construction Conference, Las Vegas, NV, Sep. 21-27, 2009, CRC Press, Leiden: Netherlands, 2010. 10. ASTM C-1688. “Standard Test Method for Density and Void Content of Freshly Mixed Pervious Concrete,” Annual Book of ASTM Standards 4(2), 2008, West Conshohocken, PA: ASTM International. 11. ASTM C-1701. “Standard Test Method for Infiltration Rate of In Place Pervious Concrete,” Annual Book of ASTM Standards 4(2), 2009, West Conshohocken, PA: ASTM International. 12. Concrete Promotional Group (CPG) MO/KS American Concrete Pavement Association “Specifiers Guider to Pervious Concrete Pavement in the Greater Kansas City Area,” Overland Park, KS, 2009. Available on-line at www.concretepromotion.com 13. Kevern, J.T., Schaefer, V.R., and Wang, K. “Design of Pervious Concrete Mixtures,” Freeware, Kansas City, MO, 2009. Available on-line at http://k.web.umkc.edu/kevernj/ 14. Mata, L. “Sedimentation of Pervious Concrete Systems,” Dissertation North Carolina State University, Raleigh, NC, 2008. 15. Haselbach, L., Valavala, S., and Montes, F. “Permeability Predictions for Sand Clogged Portland Cement Pervious Concrete Pavement Systems,” Journal of Environmental Management, 2006, v81, pp 42-49.

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16. Cooley, L. A., Brumfield, J.W., Mallick, R. B., Magower, W. S., Partle, M., Poulikakos L., and Hicks, G. (2009) “NCHRP Report 640: Construction and Maintenance Practices for Permeable Friction Courses,” Transportation Research Board, Washington, D.C. 17. Ferguson, B. K. Porous Pavements. Taylor and Francis Group. New York, NY, 2005. 18. Schaefer, V. R., Kevern, J.T., and Wang, K. “A Retrospective Look at the Field Performance of Iowa’s First Pervious Concrete Sections as of Spring 2008.” CD-ROM. Proceedings of the 2008 NRMCA Concrete Technology Forum – Focus on Pervious Concrete, 2008, Denver, CO. 19. Delatte, N., Miller, D., and Mrkajic, M. (2007) “Portland Cement Pervious Concrete: Field Performance Investigation on Parking Lot and Roadway Pavements.” Final Report of the RMC Research and Education Foundation, Silver Springs, MD. http://www.rmcFoundation.org/newsite/images/Long%20Term%20Field%20Performance%20of%20Per vious%20Final%20Report.pdf 20. Kevern, J.T., Schaefer, V.R., and Wang, K. “Temperature Behavior of a Pervious Concrete System,” Transportation Research Record: Journal of the Transportation Research Board (TRB), Construction 2009 No. 2098.

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