A Study of the Sand Patch and outflow meter methods of pavement surface texture measurement

A study of the sand patch and outflow meter methods of pavement surface texture measurement was complecated. include in this study was repeatability testing and testing to determine the degree to which pavement surface texture, as measuredby these procedures, correllates with pavement coefficient of friction, skid number adn skid number speed gradient. Test locations were selected on open graded and dense graded aphalt concrete, chip seal an fog seal asphalt concrete an new polished and grooved PCC pavement. The result of the testing indicated that the repeatablity of the sandpatch test procedures studied was poor to fair and that the outflow meter test result were indenpendent of water temperature. A general trend toward higher skid numbers and coefficients of friction was evident with increasing texture depth, as measured with both the modified sand patch and the outflow meter procedures. However, neither relations was considered definitive enough to use as a basis for a minimum texture depth constructions specification requirement for pavement surfaces. also, neither method provided a definitive measure of skid number speed gradient.