Research on Adhesive Properties between Asphalt and Aggregates at High Temperature

Abstract

In order to achieve a quantitative evaluation of adhesion from the microscopic point of view, based on the variation law of the contact angle in the process of asphalt spreading at the aggregate surface, an evaluation index that can quantitatively characterize the adhesive properties of asphalt and aggregate is presented. The image information of the contact angle is collected based on wetting theory and sessile drop method at different temperatures. The technical parameters are extracted from the fitting equation of the contact angle, and the quantitative analysis of the adhesive performance is realized. The result shows that (1) in the process of the asphalt spreading at the aggregate surface, the equation for the relationship between the contact angle and time is in accordance with power function y = Axa, the constant term A in the power function represents the size of the initial contact angle, and the initial state of contact angle is related to the viscosity state of the asphalt at the same temperature, which represents of the asphalt. There is a linear relationship between the constant term A and the asphalt viscosity η at log-log plot; and (2) the index a of the power function represents the diffusion rate of asphalt at the aggregate surface and reflects the wetting and the adhesive properties between the asphalt and the aggregate; and (3) the diffusion rate of three graded matrix asphalts at the surface of diabase tested in this research has a higher temperature sensitivity, and the wetting and the adhesive properties between the asphalt and the diabase is better than those of limestone.