Evaluation of ultrasound method for determining aggregate gradations in asphaltic concrete mixes
The purpose of this study is to evaluate a geotechnical method, ultrasound, to detect aggregate gradation differences in asphaltic concrete pavements. Empirical data had previously been used to suggest that the more coarse the gradation, the less incidence's of rutting. It is my thesis that the more coarse the gradation, the higher the velocity of a sound wave through the asphalt concrete. This being the case, the velocity measure can be used in a design or field quality control procedure as a correlation to a performance test to choose a coarse gradation that has non-rutting field performance properties. Tests were performed on actual production quality control samples of various gradation types to demonstrate that the ultrasound velocities detect gradation.