Application of Asphalt-aggregates Interfacial Energies to Evaluate Moisture-induced Damage of Warm Mix Asphalt

With increasing environmental awareness and high oil prices, use of warm mix asphalt (WMA) is gaining popularity in the asphalt industry. Different WMA technologies including use of additives to reduce the mixing and compaction temperatures are being applied. The present study uses the surface free energy (SFE) method as a mechanistic framework to evaluate the moisture susceptibility of warm mix asphalt (WMA) with Evotherm® WMA-additive. The SFE components of a modified PG64-22 asphalt binder with different percentages of Evotherm® and selected aggregates were measured in the laboratory. The work of adhesion, the work of debonding, and energy ratios were estimated to assess the moisture-induced damage potential of combinations of neat and Evotherm®-modified asphalt binders and different aggregates. The results indicated that use of Evotherm® resulted in increase in total SFE and work of adhesion and a reduction in the work of debonding, indicating a better possible aggregate-asphalt binder bond and lower moisture susceptibility potential. It is expected that the present study would be helpful in understanding the moisture-damage potential of flexible pavements constructed with WMA technologies.