ADHESION AND DISBONDING MECHANISMS OF ASPHALT USED IN HIGHWAY CONSTRUCTION AND MAINTENANCE

The paper considers the asphalt adhesion and disbonding mechanisms from a chemical viewpoint, with the object of relating the observed physical phenomena to the constitutions of the participating substances and to the nature of their mutual interactions. It takes into account the properties of the asphalt/air/mineral, asphalt/water and mineral aggregate/water interfaces including, where relevant, the influence of adhesion additives. The combined results make it possible to compose a picture of the steps involved both in the establishment of adhesion and in disbonding under the influence of water. Proposed mechanisms are then tested using laboratory disbonding experiments with selected systems. The outcome enables a comparison of the chemical approach with results derived from wetting studies, and speculations about the consequences which the conclusions may have for the real world of practice.