Detection of Surface Segregation using LASER

This paper describes the research funded by New Jersey Department of Transportation to develop a basis for an automated technology to quantify segregation that occurs during construction of hot mix asphalt concrete pavements. A laser-based system was used for detection of surface segregation. Two segregated test sections and a control test section were tested to evaluate the applicability of laser texture method to detect and quantify segregation. Laser texture data were gathered from all three sites, and sand patch and nuclear density tests were performed at every 25 ft intervals of three sections. In addition to the above, visual surveys were performed to confirm the measurements. Based on the test results it was found that the nuclear density test could not be used to detect segregation but it can be used as a confirmation test. The laser texture data showed the presence of segregation by consistently repeated texture peaks that occurred at approximately 100-foot intervals. Test results from the control section were used to establish a correlation between sand patch test (a quantitative test to determine segregation) and laser texture data. This correlation will be used to calibrate laser texture data to quantify surface segregation of asphalt pavements.