Methods to quantify interfacial adhesion and debonding in bitumen-aggregate systems in dry and wet conditions

The adhesive bond strength between bitumen and aggregate strongly impacts the strength and durability of asphalt mixtures. The primary mechanism of adhesion between these materials is due to their surface free energies and chemical interaction potentials. Test methods to efficiently quantify these properties have not been investigated until recently. This paper presents a methodology to quantify the adhesive bond strength between bitumen and aggregate in a dry condition and the propensity for water to displace bitumen from its interface with the aggregate. The Universal Sorption Device (USD) and the Wilhelmy plate device were used to measure the surface free energy components of selected aggregates and bitumen, respectively. Principles of thermodynamics were used to compute the work of adhesion between these two materials and their propensity to debond in the presence of water using the surface free energy components of these materials. Results indicate that these parameters depend on the physio-chemical properties of both the bitumen and the aggregate. This paper also demonstrates a procedure to select combinations of bitumen and aggregate that will result in asphalt mixtures that are more resistant to moisture induced damage based on the surface free energy of these materials. 2007 Taylor & Francis Group, London.

Methods to quantify interfacial adhesion and debonding in bitumen-aggregate systems in dry and wet conditions Conference Paper