Modified PATTI test for the characterization of adhesion and cohesion properties of asphalt binders

It is well known that aggregate-asphalt bond is of fundamental importance for mechanical response and moisture susceptibility of asphalt mixtures. Many researchers have studied moisture effects on the binder adhesion-disbonding properties and their role in defining asphalt mixture performance, but a suitable system to measure binder adhesive properties to aggregates directly is not available yet. This paper includes a study to modify the Pneumatic Adhesion Tensile Testing Instrument (PATTI), which is a standard method used for paints or coatings. The modification is aimed at developing a reliable and practical test protocol for directly evaluating the adhesion/cohesion properties of asphalt binders. To achieve this goal, different asphalt binders and several test variables were varied to study their influence on pulloff strength. The analysis of the results collected indicates that the modified PATTI test protocol show high promise for evaluating adhesive bond strength and moisture susceptibility of asphalt binders. Moreover, the test appears to be simple and practical to allow discriminating different asphalt binders with different adhesion characteristics.