ODOT_TM780_Sand_Circle~1.pdf

ODOT Provisional TM 780

Provisional Method of Test for

Measurement of Texture by the Sand Circle Method

SCOPE

This test procedure covers the determination of the average texture depth of a paved surface using sand to give the volume of voids, performed by the Engineer. This method is suitable for the measurement of surfaces with average texture depths greater than 0.45mm or 0.018” (less than 350mm or 14” sand circle diameter).

REFERENCES

ODOT TM 400

Oregon Chip Seal Design Guide

APPARATUS

1. Tape measure or ruler graduated in millimeters at least 400mm (16”) in length.

2. A soft brush or hand broom.

3. A straightedge between 150mm (6”) and 175mm (7”) in length.

4. A spreader tool - A flat, hard disc approximately 25mm (1”) thick and 60 to 75mm (2.5 to 3.0”) in diameter shall be used to spread the sand. The bottom surface or face of the disc shall be covered with a hard rubber material and a suitable handle may be attached to the top surface of the disc.

• Note – An ice hockey puck is suitable for use as the hard rubber material in this test method.

5. A sand measuring cylinders 30 to 45mm (1.2 to 1.8”) in diameter having an internal volume of 45

+/- 0.5ml (2.75 in3 +/- 0.03 in3). The top of the cylinder shall be machined flat to assist striking off.

6. A quantity of clean dry sand with well-rounded grains, I00% passing the 600 µm (#30 sieve) and I00% retained on the 300µm (#50 sieve).

PROCEDURE

1. Select a test location randomly and in accordance with agency requirements (ODOT TM 400) for each sublot or partial sublot. At each random location, the operator shall take the average of five equally spaced (12” to 18” apart) measurements in the outer wheel path. Measure the outside wheel path at 9’ +/- ½’ from the lane divider (center line marking), starting with the random location and progressing up-station.

2. Sweep the test area using a brush or hand broom.

3. Fill the cylinder with sand and tap lightly until the sand ceases to compact. Carefully strike off the top surface of the cylinder with the straightedge.

4. Pour out the sand in a conical pile in the center of the area to be tested. (In windy conditions, the use of a screen to surround the sand is recommended).

5. Using the spreader tool, spread the sand into a circular patch so that the surface depressions are filled to the level of the tops of the stones (see figure I). The tops of the larger stones (see figure I). The tops of the larger stones should only just be visible through the sand layer.

6. Measure the diameter of the patch twice. The second measurement shall be approximately at a right angle to the first measurement. Average the measurements to determine D, the sand circle diameter.

(i) measured quantity or sand poured on road

(ii) Sand spread to form circular patch

Abnormal large chips should be ignored when screeding sand

Figure 1. Sand Surface Depression Examples

CALCULATION

Calculate the average texture depth for each sublot or partial sublot with the following equation:

REPORT

1. Report the sand circle diameter in millimeters to the nearest 5mm (0.20 in.). Textures producing diameters in excess of 350mm (14 in.) are to be reported as "greater than 350mm" (14 in.).

2. Report the average texture depth to the nearest 0.1mm (0.004 in.).

3. Report the name of the operator performing the test.

4. Report the GPS location of the test.

𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑ℎ =

57300

𝐷𝐷

(𝐷𝐷 𝑖𝑖𝑖𝑖 𝑚𝑚𝑚𝑚 )

Appendix “A” - TM780

Performance Measurement – Macro Texture

Texture Depth, Design Life, and Life Expectancy Calculations

Scope

This appendix covers the calculations used to determine the required texture depth at one year, the equivalent light vehicle factor, and the expected life of a chip seal. These results help develop the initial chip seal design and determine how the product compares to the original design and any potential price adjustments.

Calculations

TD1 = 0.07 ALD log10 Yd + 0.9

Where:

• TD1 = Required texture depth after one year post-construction (mm)

• Yd = Emulsified Asphalt Surface Treatment design life (years)

• ALD = Average Least Dimension of the Emulsified Asphalt Surface Treatment aggregate (mm) – see

Oregon Chip Seal Design Guide.

Calculate the Average Least Dimension as follows:

𝐴𝐴𝐴𝐴𝐴𝐴 =

𝑀𝑀

1.139285 + (0.011506)(𝐹𝐹𝐹𝐹)

• M = Median Particle Size of the Chip Seal aggregate (mm), defined as a theoretical sieve size in which 50% of the aggregates pass as determined from the aggregate gradation chart.

• FI = Flakiness Index, defined as the measure of the shape of the aggregate as determined by ODOT Provisional TM 782.

Calculate the Emulsified Asphalt Surface Treatment design life as follows:

Yd = 4.916 + 1.68 (ALD) - (1.03 + 0.219 ALD) log10 (ELV)

• ELV = Equivalent Light Vehicles (per lane, per day)

Calculate the Equivalent Light Vehicles as:

𝐸𝐸𝐸𝐸𝐸𝐸 =

𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴

𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑒𝑒𝑒𝑒 𝑜𝑜𝑜𝑜 𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙 �

1 +

9(𝐻𝐻𝐻𝐻𝐻𝐻)

100 �

• AADT = Annual Average Daily Traffic

• HCV = Percentage of Trucks in AADT. Trucks are considered a Class 4-13 Vehicle according to FHWA vehicle classifications.

To ensure that the texture of the Emulsified Asphalt Surface Treatment is above the required minimum, the average of the five tests will be reduced by a factor dependent on the standard deviation. The measured texture depth must meet the following criteria:

X - 0.519S > 0.07 ALD log10 Yd + 0.9

• X = average of the 5 texture depth measurements

• S = sample standard deviation calculated for the 5 tests

Note: X - 0.519S is commonly termed the ‘texture depth criterion’ or Td.

If the measured texture depth is below the required texture depth (i.e. Td < TD1), then the expected life of the Emulsified Asphalt Surface Treatment after the one year Maintenance Period, Yf, is calculated as follows:

Yf = antilog [(Td-0.9)/(0.07*ALD)]

• Td = Texture depth criterion, defined above.

If the expected life, Yf, is less than the design life, Yd, of the Emulsified Asphalt Surface Treatment then the sublot does not meet the performance requirement and is subject to the price adjustment in SP00710.95.

This test procedure covers the determination of the average texture depth of a paved surface using sand to give the volume of voids, performed by the Engineer. This method is suitable for the measurement of surfaces with average texture depths greater...