Pavement texture depth is an important indicator for evaluating pavement macrotexture and skid resistance performance. The Manual Sand Patch Method is a simple and widely used method for measuring the texture depth of asphalt pavements and non-grooved concrete pavements. This article introduces the test procedure, calculation method, and reporting requirements for pavement texture depth measurement using the sand patch method.

1. Scope

This method is applicable for measuring the surface texture depth of asphalt pavements and non-grooved cement concrete pavements. It is used to evaluate the skid resistance performance of pavement surfaces.

Technical Requirements for Apparatus and Materials:

(1) Manual Sand Patch Apparatus:

Consists of a sand measuring cylinder and a spreading disc.

(2) Measuring Sand:

A sufficient quantity of dry, clean, and uniform sand with a particle size of 0.15–0.30 mm.

(3) Measuring Ruler:

A steel ruler or dedicated texture depth gauge.

(4) Others:

Sand container (small shovel), broom or brush, wind shield, and other accessories.

2. Method and Procedure

2.1 Preparation

(1) Preparation of Measuring Sand:
Select clean fine sand, dry it, and sieve it. The sand particles with a size range of 0.15–0.30 mm shall be collected and stored in a suitable container for testing. The measuring sand shall be used only once during each test and shall not be reused.

(2) Selection of Test Location:
Select the transverse test position of the road section according to the method specified in T 0902 of this specification. The test points shall be located within the wheel track area of the traffic lane, and the distance from the pavement edge shall be not less than 1 m.

2.2 Test Procedure

(1) Clean the pavement surface around the test point using a broom or brush. The cleaned area shall be not less than 30 cm × 30 cm.

(2) Slowly pour the prepared measuring sand into the measuring cylinder until the sand forms a cone slightly above the top of the cylinder. Hold the upper part of the cylinder and gently tap the middle section of the cylinder three times with a steel ruler. Then use a scraper to level the sand flush with the edge of the cylinder opening.

Note:
Do not directly use the measuring cylinder for storing or filling sand, as this may affect the uniformity of sand density.

(3) Pour the sand onto the pavement surface. Use the spreading disc to spread the sand repeatedly from the center outward, applying slight pressure to distribute the sand evenly and fill the surface voids. Spread the sand into a circular shape as much as possible, ensuring that no loose sand remains floating on the surface. Avoid applying excessive force or pushing the sand outward during spreading.

(4) Measure the diameter of the formed sand circle in two perpendicular directions using a steel ruler and calculate the average value. The measurement shall be accurate to 1 mm. A dedicated texture depth gauge may also be used to directly measure the pavement texture depth.

(5) Repeat the test at the same location at least three times using the above procedure. The three test points shall all be located within the wheel track area, with a spacing of 3–5 m between adjacent points. Tests at the same location shall be performed by the same operator. The test position of the location shall be represented by the middle test point.

3. Data Processing

3.1 Calculation of Pavement Texture Depth

The test result of the pavement texture depth (TD) shall be calculated according to Equation (T 0961):

TD=1000V/πD²/4=31831/D²

(T 0961)

Where:

· V — Volume of sand (25 cm³);

· D — Average diameter of the spread sand circle (mm).

3.2 Test Result Processing

At each test location, the average value of the three pavement texture depth measurements shall be taken as the test result. The result shall be accurate to 0.01 mm.

When the average value is less than 0.2 mm, the test result shall be expressed as <0.2 mm.

3.3 Statistical Analysis

According to the requirements specified in Appendix B of this specification, calculate the following parameters for each tested pavement section:

· Average pavement texture depth;

· Standard deviation;

· Coefficient of variation.

4. Test Report

The test report shall include the following technical information:

(1) Information of the tested pavement section (chainage, test location, etc.).

(2) Pavement texture depth.

(3) The average value, standard deviation, and coefficient of variation of the pavement texture depth for the tested section.