Effect of Overheating on Adhesion of Asphalt Binder with Aggregates

Adhesion of asphalt binder with aggregates affects pavement quality, performance, and serviceability. The lack of bonding between binder and aggregates can cause stripping and significant reduction in pavement’s design life. Numerous studies have concluded that overheating can result in asphalt binder becoming more stiff, viscous and less penetrable, due to loss of volatile oils. This research aimed to study the effect in the degree of adhesion between aggregates and binder with an increase in the production temperature. ARL 60/70 bitumen was heated to temperatures above its mixing temperature with various increments to study the adhesive behavior. Samples were heated at 156, 160, 164, 168, and 172 °C. The adhesive properties of bitumen were evaluated on loose asphalt mix samples using Rolling Bottle Test (RBT) and Bitumen Bond Strength (BBS) test. Results indicated that as temperature increased, bitumen–aggregate bond was affected adversely. The BBS indicated a loss of 46.3% in pull of tensile strength, while RBT showed loss of 55.5% in coverage after 72 hours.