Characterization of Aggregate Surface Energy Using the Universal Sorption Device

Abstract

Moisture damage in asphalt concrete pavements is a major cause for high maintenance costs of state and federal highways. Moisture damage in asphalt concrete is largely due to loss of adhesion between bitumen and aggregate, and loss of cohesive strength in the mastic (bitumen and mineral filler). Surface energy components of bitumen and aggregate are used to calculate their interfacial bond strength and effectively quantify moisture susceptibility of asphalt concrete mixes. This technology has several advantages over conventional mechanical tests currently being used to identify moisture susceptible mixes. However, accurate surface energy characterization of bitumen and aggregate is the key element to calculate interfacial bond strengths. This paper presents development of a sorption based method to measure specific surface area and surface energy components of aggregate. Measured surface energy components and precision statements are presented for five aggregates. The paper also illustrates application of bond strengths calculated from surface energy components of aggregate and bitumen in the selection process of compatible pairs of aggregate and bitumen to produce a durable mix.