EFFECT OF MICROWAVE HEATING ON ADHESION AND MOISTURE DAMAGE OF ASPHALT MIXTURES

Microwave energy has been demonstrated to be capable of heating pavements rapidly, uniformly, and to depths of up to 5 in. without overheating the surface. Microwave treatment of asphalt mixtures is believed to have the potential of improving asphalt adhesion to aggregate. Presented in this paper is the work that was carried out to investigate this aspect of microwave heating in two ways. First, possible mechanisms by which adhesion improvement may occur when mixtures are exposed to microwave energy are discussed. Second, results of resilient modulus and split tension tests conducted on mixtures that were prepared in the laboratory using a convection oven and a kitchen-type microwave oven are reported. The study involved preparing three groups of mixtures: plain, virgin with an antistripping additive, and artificially aged materials. Test results indicate that microwave energy treatment of asphalt mixtures improves their adhesion and their resistance to water damage.