Interfacial fracture energy: An indicator of bituminous material adhesion

This paper demonstrates that the pressurized blister test can be an effective method to predict binder-aggregate bonding. Recently, the blister test has been introduced as a reliable approach to predict the bonding between bituminous sealant and aggregate. Since this test measures a geometry-independent parameter that is an inherent property of the interface, the test can be applied to any bituminous material, from the softest bituminous crack sealant to the most brittle binder. With very brittle material, cohesive failure becomes a concern. Such a failure can be easily prevented by an increase in the thickness of the adhesive specimen. However, an increase in specimen thickness also gives rise to shear forces that cannot be neglected in the analysis. Utilizing theoretical and experimental analyses, this paper presents the effect of shear forces on the interfacial fracture energy (IFE) of adhesive bituminous materials. The effect of shear forces on blister deflection is shown as a function of material thickness. In addition, the dependence of IFE of bituminous materials on temperature and rate of loading was investigated through laboratory testing. An optimum temperature and loading rate can be identified for each material where IFE is optimized. This may help select appropriate binder/sealant - aggregate pairs for improved performance under defined environmental conditions.