Florida Department of

TRANSPORTATION Asphalt Paving Level 1 Appendix 1 Additional Practice Problems for Tack Coat, Mix Spread Rate, and Cross-Slope

Tack Coat Spread Rate: A typical distributor calibration chart, the table for temperature correction for emulsified asphalts, and the table for temperature correction for asphalt cement tack are found at the back of Module 3 of this manual. Using the charts - The temperature correction chart is a simple chart that has columns for temperature with the correction factor in the column to the right of the temperature. These charts have correction factors from 1 degree to 500 degrees Fahrenheit. There are two of these charts in this section. It is important to know which chart to use. One of the charts is used for the emulsified asphalts and is usually used during daytime conditions. The other chart is used for PG 56-22 asphalt cement tack that is commonly used during night paving. A typical distributer calibration chart is included in this section for determining the amount of asphalt in the distributer. This chart has depth with the corresponding volume in gallons in the column to the right of the depth. Depths are measured using a distributer stick which directly measures the depth of the asphalt in the distributer. The measurements are in inches and 1/16 of inches. For example: 16/8 is equivalent to 16 8/16 inches deep. Using the chart, look up 16/8. The volume is 1203 gallons of asphalt.

Asphalt Paving Level 1 Practice Problems

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Florida Department of

TRANSPORTATION Tack Coat Spread Rate Example Here is an example of calculating a tack spread rate: A tack shot started at Station 118 + 50 and ended at Station 144 + 75. The shot width is 12 feet. The beginning reading on the tank was 11/13. The ending reading was 18/14. Tack was an emulsified asphalt that was at 160º degrees Fahrenheit. The desired spread rate is 0.05 gal/sq yd. Solution: Step 1 - Find the length of the shot. Sta. 144 + 75 - Sta. 118 + 50 26 + 25 = 2,625 lineal feet Step 2 - Determine the square yards of pavement spread. S.Y. = Lineal feet x width = 2,625 x 12 = 3,500 sq yd 9 sq ft/sq yd 9 Step 3 - Determine the number of gallons used. This is the number of gallons at 60 degrees Fahrenheit. 3a) Number of gallons at 160º F From the Distributor Chart tables. Beginning Reading 11/13 = 1,319 gallons Ending Reading 18/14 = 1,140 gallons Gallons used at 160º F = 179 gallons 3b)

Correct the gallons at 160º F to gallons at 60º F Using the Emulsified Asphalt Temperature Correction Chart, find the correction factor for 160º F 160º F correction factor = 0.9756 Gallons at 60 º F = gallons at 160º F x correction factor = 179 x 0.9756 = 174.63 gallons

Step 4 - Calculate Spread Spread Rate = gallons used at 60º F square yards covered = 174.63 gal = 0.0499 gal/sq yd = 0.05 gal/sq yd 3,500 sq yd Asphalt Paving Level 1 Practice Problems

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Florida Department of

TRANSPORTATION PRACTICE PROBLEMS - TACK SPREAD RATE 1.

Use the charts to complete this question. The tack shot is made. Using the following information, calculate the quantity (gallons used), tack spread rate: Tack shot from Station 795+85 to Station 817+00. Width of the shot is 11 feet 6 inches. The beginning tank measurement is 11/8. The ending tank measurement is 16/15. The temperature of the emulsified asphalt was 170º F. Beginning reading = ____________ Ending reading = ______________ Quantity = gal Spread rate = gal/sq yd

2.

Use the charts to complete this question. Tack shot is made. Using the following information, calculate the quantity (gallons used), and the tack spread rates: Next shot went from Station 817+50 to Station 852+50. Width of the shot is 13 feet. The beginning tank measurement is 16/15 The ending tank measurement is 32/3. The temperature of the PG 56-22 is 285º F. Beginning reading = ______________ Ending reading = _____________ Quantity = gal Spread Rate = gal/sq yd

Asphalt Paving Level 1 Practice Problems

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Florida Department of

TRANSPORTATION 3.

Use the charts to complete this question. Tack shot is made. Using the following information, calculate the quantity (gallons used), and the tack spread rates: Next shot went from Station 687+15 to Station 711+60. Width of the shot is 12 feet. Beginning tank measurement is 16/15. Ending tank reading is 23/2. The temperature of the emulsified asphalt was 165º F. Beginning reading = ______________ Ending reading = _____________ Quantity = gal Spread rate = gal/sq yd

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Florida Department of

TRANSPORTATION Asphalt Mix Spread Rate: The specifications require the Contractor to occasionally check the thickness of the asphalt layer. Once the thickness is checked and an adjustment is made, the paving machine must be allowed to travel a minimum of 32 feet before checking again. A rough thickness is obtained using a thickness probe. The thickness probe should be set to account for roll down which amounts to about 20-25% of the loose thickness. Example: To assure a compacted thickness of 1 inch, the loose thickness should be about 1 ¼ inches. A loose thickness of 2 ½ inches will produce a compacted thickness of about 2 inches. The exact method is to calculate the actual thickness by determining the mix spread rate in pounds per square yard (lb/sq yd). Calculate the spread rate periodically throughout the day and at the end of the day and record on the appropriate report. Remember the paver will attempt to level the surface it is paving over. Therefore, the paver will lay the mix thicker in some areas and thinner in others. The paver cannot lay a uniform mat thickness and place a smooth and level mat at the same time unless the surface below is smooth and level. Do not get into the habit of constantly checking thickness and asking for adjustments. A better method is to check the yield several times a day and make adjustments.

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Florida Department of

TRANSPORTATION HMA Spread rate or Yield Example: Four loads of a leveling mix are spread between Station 15+30 and Station 38+50. Width is 12 ft. The net weights of the trucks are: 42,130 lb 39,270 lb 37,420 lb 40,750 lb Total net weight = 159,570 lb Mix spread = Total net weight of asphalt mix (lb) Area covered (square yards) Area covered = Spread length (ft) x spread width (ft) 9 sq ft/sq yd Area covered = 2320 ft x 12 ft wide = 3093.33 sq yd 9 sq ft /sq yd Mix spread =

159,570 lb = 51.6 lb/sq yd 3093.33 sq yd

Asphalt Paving Level 1 Practice Problems

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Florida Department of

TRANSPORTATION PRACTICE PROBLEM - MIX SPREAD RATE Calculate the requested information: 1.

Laying Superpave mix. Five loads of mix total 196,680 lb. The area is 967 sq yd. What is the spread rate? Spread rate =

2.

Laying SP-19 mix. Mat width is12 feet. Placed from Station 18+80 to Station 25 +30. Five truckloads were spread with the following net weights: 41,240 lb; 38,890 lb; 41,120 lb; 39,150 lb; and 43,650 lb. 1. Square yards = 2. Total weight = 3. Spread rate =

3.

Laying SP-12.5 mix. Mat width is 12 feet. Placed from Station 798+00 to Station 806+50. Four truckloads were spread with the following net weights: 38,880 lb; 43,740 lb; 38,650 lb; and 36,940 lb. 1. Square yards = 2. Total weight = 3. Spread rate =

4.

Laying SP-12.5 mix. Mat width is12.5 feet. Placed from Station 10+50 to Station 15+60. Three truckloads were placed with the following net weights: 40,050 lb; 37,970 lb; and 41,190 lb. 1. Square yards = 2. Total weight = 3. Spread rate =

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Florida Department of

TRANSPORTATION Cross Slope: Another aspect of the paving operation is to check the cross-slope of the mat to ensure the pavement will drain properly. Cross-slope is important and contributes to pavement performance. On mill and overlay projects, cross-slope deficiencies can be corrected during the milling stage by a combination of milling and leveling, or by placing overbuild layers with the paver. Use a straightedge and place a level centered on the top of the straightedge. Raise the straightedge up until the bubble is level. Measure with a ruler the gap between the lower end of the straightedge and the mat. Divide this by the length of the straightedge and multiply by 100 to convert to percent. Round to the nearest tenth of a percent. Compare this slope to the slope required on the plans and make any necessary adjustments. Cross Slope Calculation Example: 1.

You have a level that is 4 feet long. The measurement at the end of the level from the level to the roadway is 1 tenth of a foot (0.10 feet). What is the percent cross slope? Compute the slope - 0.10 ft / 4 ft = 0.025 X 100 = 2.5 %

2.

You have a level that is 6 feet long. The measurement at the end of the level from the level to the roadway is one inch. What is the percent cross slope? Convert the one inch to tenths of a foot.

1”/ 12” =

0.0833 feet

Compute the slope - 0.0833 ft / 6 ft = 0.0138 X 100 = 1.38% or 1.4 %

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Florida Department of

TRANSPORTATION PRACTICE PROBLEM - CALCULATING CROSS SLOPE 1.

You have a level that is 5 feet long. The measurement at the end of the level from the level to the roadway is 0.15 feet. What is the percent cross slope?

2.

You have a level that is 6 feet long. The measurement at the end of the level from the level to the roadway is one inch. What is the percent cross slope?

3.

You have a level that is 5 feet long. The measurement at the end of the level from the level to the roadway is 0.08 feet. What is the percent cross slope?

4.

You have a level that is 10 feet long. The measurement at the end of the level from the level to the roadway is 1.5 inches. What is the percent cross slope?

Asphalt Paving Level 1 Practice Problems

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Florida Department of

TRANSPORTATION

ANSWERS TO PRACTICE PROBLEMS

Asphalt Paving Level 1 Practice Problems

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Florida Department of

TRANSPORTATION Solution to Tack Spread Rate Practice Problems Problem 1 Beginning reading was 11/8 = 1325 Ending reading was 16/15 = 1193 Temperature correction = 0.9732 Corrected quantity = 128.46 gal Area = 2702.50 sq yd Spread rate = 0.05 gal/sq yd Problem 2 Beginning reading was 16/15 = 1193 Ending reading was 32/3 = 738 Temperature correction = 0.9270 Corrected quantity = 421.79 gal Area = 5055.55 sq yd Spread Rate = 0.08 gal/sq yd Problem 3 Beginning reading was 16/15 = 1193 Ending reading was 23/2 = 1023 Temperature correction = 0.9744 Corrected quantity = 165.65 gal Area = 3260.00 sq yd Spread rate = 0.05 gal/sq yd

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Florida Department of

TRANSPORTATION Solution to Mix Spread Rate Practice Problems 1.

Laying SP-19 mix. Five loads of mix total 196,680 lb. The area is 967 sq yd. What is the spread rate? Spread rate = 203.3 lb/sq yd

2.

Laying SP-19 mix. Mat width is 12 feet. Placed from Station 18+80 to Station 25 +30. Five truckloads were spread with the following net weights: 41,240 lb; 38,890 lb; 41,120 lb; 39,150 lb; and 43,650 lb. Square yards = 866.66 sq yd Total weight = 204,050 lb Spread rate = 235.4 lb/sq yd

3.

Laying SP-12.5. Mat width is 12 feet. Placed from Station 798+00 to Station 806+50. Four truckloads were spread with the following net weights: 38,880 lb; 43,740 lb; 38,650 lb; and 36,940 lb. Square yards = 1,133 sq yd Total weight = 158,210 lb Spread rate = 139.6 lb/sq yd

4.

Laying SP-12.5 mix. Mat width is 12.5 feet. Placed from Station 10+50 to Station 15+60. Three truckloads were spread with the following net weights: 40,050 lb; 37,970 lb; and 41,190 lb. Square yards = 708.33 sq yd Total weight = 119,210 lb Spread rate = 168.3 lb/sq yd

Asphalt Paving Level 1 Practice Problems

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Florida Department of

TRANSPORTATION Solution to Cross Slope Practice Problems 1.

0.15 ft / 5 ft = 0.03 X 100 = 3.0%

2.

1.0 in / 72 in = 0.0138 X 100 = 1.38% or 1.4%

3.

0.08 ft / 5 ft = 0.016 X 100 = 1.6%

4.

1.5 in / 120 in = 0.0125 X 100 = .25% or 1.3%

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