| From the need to get from here to there, the road was born. The ability to move people and goods across large distances is the fundamental building block of civilization. Despite the enormous costs associated with road construction, little has been done to study asphalt-aggregate cohesion and adhesion, the mechanism that binds asphalt to the aggregate. This work is the first attempt to describe adhesion and cohesion of asphalt-aggregate systems in terms of fundamental surface science.; A framework for predicting and analyzing adhesion and cohesion in asphalt-aggregate systems has been established. Methods have been developed to describe the surface free energy of asphalts and aggregates. Specifically, the surface free energy of asphalts are measured using the Wilhelmy plate method, and the surface free energy of aggregates are measured by Li using gas adsorption. The resulting surface free energies are used to analyze the adhesion and cohesion of asphalt aggregate systems.; The aggregates are ranked from the predictions of strength and adhesive healing performance. The asphalts are ranked from the predictions of cohesive healing, strength, and water susceptibility. The effects of the aggregates are more important in almost every case. Asphalts are important only in cohesive healing; asphalts should be chosen based upon physical property data (aging). The influence of additives is not clear because of the small number of samples studied, however, some promising possibilities exist; rubber appears to be a superior performer.; This work is the first to apply fundamental surface science to asphalt-aggregate systems. The usefulness of this study lies in understanding asphalt-aggregate adhesion and in prediction of crack formation. The results of this investigation are a part of the much larger problem of designing and manufacturing superior asphalts to improve road life-times. |
