Sand Patch Test Research Articles

Evaluation of Circular Texture Meter for Measuring Surface Texture of Pavements

The circular texture (CT) meter is a laser-based device for measuring the mean profile depth (MPD) of pavement at a static location. MPD measurements from the CT meter and mean texture depth measurements from the sand patch test were obtained in five random locations in each of 45 sections of the 2000 National Center for Asphalt Technology (NCAT) test track. The NCAT test track provides a wide range of surface types, including coarse and fine dense graded Superpave® mixes, Hveem mixes, stone mastic asphalt, and Novachip. Testing indicated that the CT meter produced results comparable with the ASTM E965 sand patch test. When open-graded mixtures were excluded, this study indicated that the offset was nonsignificant between CT meter and sand patch test results. Previously developed equations to predict macrotexture were found to be inadequate for the wide range of mix types and aggregate types found at the NCAT test track. An equation was developed to relate fineness modulus to macrotexture. This equation was validated with independent data collected by the Virginia Transportation Research Council. Testing conducted as part of a mini round robin indicated that two readings should be averaged to represent a single CT meter measurement. The within-lab coefficient of variation for the CT meter is estimated to be 2.3%. The between-lab coefficient of variation for the CT meter is estimated to be 4.2%. Both estimates are based on the average of two tests being reported as a single measurement.

CALCULATION OF INTERNATIONAL FRICTION INDEX USING CIRCULAR TEXTURE METER AND DYNAMIC FRICTION TESTER

The Circular Texture Meter (CTM) recently developed is a device which has a CCD Laser Displacement Sensor mounted on an aim designed to rotate on a circumference of 142 mm radius. The CTM can measure the texture with about 0.9 mm pitch on the same circumference of that coefficient of friction is measured with a D. F. Tester.In this study, we have analyzed the relationship between MPD by CTM and MTD by Sand Patch Test. Also, we have measured the coefficient of friction with D. F. Tester at the same spots as that the texture was measured by the CTM.We have observed a good correlation between the MPD by CTM and the MTD by the Sand Patch Test. And it is found that International Friction Index can be computed from the CTM measurements and the D. F. Tester measurements.

MEASUREMENT OF ROAD SURFACE TEXTURE: AN EXAMINATION.

Keywords SOUTHAMPTON UNIVERSITY ROADS, SURFACES, TEXTURE, MEASUREMENT, TESTS, SAND, STANDARD, PATCH, METHODS, TOLERANCES, CONTRACTS, CONCRETE, SPECIMENS, TILES, BRUSHED, EXPOSED, AGGREGATES, FINISHES, TWO DIMENSIONAL, PROFILES, SKIDDING, RESISTANCE, MICROTEXTURE, MACROTEXTURE, PAVEMENTS, FLEXIBLE, RIGID, COMPOSITE, VARIATIONS, VARIABILITY... Show All

Comparison of Road Profilers

Devices available to measure road profiles vary from the hand-held Dipstick to high-speed, vehicle-based profilers. High-speed, vehicle-based profilers generally use an ultrasonic, laser, or optical measuring system. A profiler calibration study was conducted by the road profiler user group in 1994 by establishing regional calibration centers in Mississippi, Nevada, Pennsylvania, and South Dakota. The study compared the data collected by the profilers with the Dipstick data, and analyzed the effect of surface texture on data collection. At each regional calibration center, asphalt concrete and portland cement concrete test sections were established. Thirty-eight road profilers belonging to state agencies, equipment manufacturers, and FHWA participated in the calibration study. Dipstick measurements and sand-patch tests were conducted at all test sites. The International Roughness Index (IRI) was used as the parameter for performing the analyses. The results of the analyses for the sites in Pennsylvania and South Dakota are presented. The agreement between Dipstick IRI and profiler IRI for a specific profiler varied from site to site. For a specific profiler at some sites, the agreement with the Dipstick IRI was good, while at other sites the agreement was poor. The profilers with ultrasonic measuring systems generally had poor agreement with Dipstick IRI values for asphalt-surfaced sites that had aggregate seal coats.

Comparison of Road Profilers

Devices available to measure road profiles vary from the hand-held Dipstick to high-speed, vehicle-based profilers. High-speed, vehicle-based profilers generally use an ultrasonic, laser, or optical measuring system. A profiler calibration study was conducted by the road profiler user group in 1994 by establishing regional calibration centers in Mississippi, Nevada, Pennsylvania, and South Dakota. The study compared the data collected by the profilers with the Dipstick data, and analyzed the effect of surface texture on data collection. At each regional calibration center, asphalt concrete and portland cement concrete test sections were established. Thirty-eight road profilers belonging to state agencies, equipment manufacturers, and FHWA participated in the calibration study. Dipstick measurements and sand-patch tests were conducted at all test sites. The International Roughness Index (IRI) was used as the parameter for performing the analyses. The results of the analyses for the sites in Pennsylvania and South Dakota are presented. The agreement between Dipstick IRI and profiler IRI for a specific profiler varied from site to site. For a specific profiler at some sites, the agreement with the Dipstick IRI was good, while at other sites the agreement was poor. The profilers with ultrasonic measuring systems generally had poor agreement with Dipstick IRI values for asphalt-surfaced sites that had aggregate seal coats.