Project Details

The objective of this research project is to develop a simple asphalt surface treatment (AST) testing system that is based on a review of existing AST test methods, the experience of the North Carolina State University (NCSU) research team gleaned from previous AST projects, and experience of field personnel who construct ASTs. The bitumen bond strength (BBS) test is identified as a promising, inexpensive, and simple test method to determine the adhesive and cohesive properties of emulsions. Also, a modified sweep test and three-dimensional (3-D) laser profiler method are developed from this study. The modified sweep test is based on the sweep test specified in ASTM D7000, but replaces the stiff-bristled brush in the original sweep tester with a free-rolling, free-spinning rubber wheel to simulate the horizontal and vertical forces induced by the front wheels of a vehicle. Also, a height adjustment mechanism and load cell are incorporated in the modified sweep test machine to ensure and maintain constant vertical pressure of the wheel on the chip seal specimen. The 3-D laser profiler is equipped with a point laser and photoelectric sensor to measure the surface profile and to take digital images of the chip seal pavement surface for the evaluation of aggregate embedment and bleeding. A preliminary investigation is undertaken to determine the aggregate embedment depth from the chip seal surface profile measured by the 3-D laser profiler, and the results indicate that the 100% valley average is close to the 50% passing sieve size. This finding can be used to establish the surface profile of chip seal pavements that have different percentages of embedment depth from the aggregate gradation.