The development of a novel test method to assess the durability of asphalt road–pavement materials

A better understanding of the adhesion mechanisms between the bitumen binder and the aggregate substrates, as employed in asphalt road pavements, is necessary to improve the durability of road–pavement materials. A new test protocol is outlined in the present paper to measure the characteristic fracture resistance of such bitumen–aggregate joints and to better understand the causes of failure of asphalt road surfaces, especially when associated with moisture ingress. The new test protocol is based upon a novel peel test which has been developed using a fracture mechanics approach to determine the adhesive fracture energy of bitumen–aggregate joints tested in both an unconditioned state (i.e., in the ‘dry’ state) and after being conditioned in an aqueous environment. Thus, the initial fracture resistance of the bitumen–aggregate can be assessed and the effects of any moisture-induced damage can be successfully quantified by the determination of the adhesive fracture energy. With these newly-developed techniques, the effects of using different aggregates and different bitumen grades may be quantitatively studied, since this test technique and recommended protocol may be readily adapted according to the requirements of different grades of bitumen, types of aggregate and required test conditions.