Characterization of Aggregate Surface Energy Using the Universal Sorption Device

TLDR

Moisture damage in asphalt concrete, driven by loss of adhesion between bitumen and aggregate and reduced mastic cohesion, is a major cost driver for highways, and accurate surface energy characterization is essential for calculating interfacial bond strengths. This study develops a sorption‑based method to measure aggregate surface area and surface energy components. The method uses sorption measurements to determine aggregate surface area and surface energy components, which are then combined with bitumen surface energy to calculate interfacial bond strengths and assess moisture susceptibility. The sorption‑based technique outperforms conventional mechanical tests, provides precise surface energy measurements for five aggregates, and enables calculation of bond strengths that guide selection of compatible aggregate‑bitumen pairs for durable mixes.

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.