Mechanical and image analysis of adhesion between mineral aggregate and bituminous binder

Abstract

Asphalt mixtures often fail due to poor interaction between mineral aggregate and bituminous binder. Therefore, many efforts are being made on adhesion improvement between the two materials. In this work, paving grade bitumen 50/70 was doped with two types of adhesion promoters. Asphalt mixtures composed of crushed aggregate Brant coated by binder were made and exposed to stripping water. Then, they were subjected to visual and digital image analysis aiming to quantify aggregate residual bitumen-coated areas. Besides, two cylindrical samples of aggregate were bonded together by a thin film of bitumen doped with adhesion promoters. After solidification of binder, force needed for separation of the two parts was measured. It was shown that residual bitumen-coated areas were increased by 20-30 % by adding adhesion promoters into binder. Mechanical adhesion of thus modified binder to aggregate was increased by up to twice.