Novel Approach to Characterize Moisture Damage in Asphalt Mixtures Based on Critical Permeability

Abstract

Moisture damage resistance assessment in asphalt mixtures traditionally relies on the tensile strength ratio (TSR) method, which may not capture the complex behavior of asphalt under moisture ingress. This study proposes an innovative multifaceted approach for assessing moisture susceptibility, challenging the overreliance on TSR, and integrating multiple intricate aspects of asphalt behavior. Employing two dense-graded and one gap-graded polymer-modified binder mixtures with nominal maximum aggregate size (NMAS) of 13 and 19 mm, the study defines threshold values for total air voids, effective air voids, indirect tensile strength, and percentage density change. Evaluations were conducted using a device selected for its dynamic capabilities in inducing stresses and creating pore pressure under elevated temperatures. This research proposes a new zone-based approach to classify mixtures as moisture-resistant, partially moisture-resistant, or moisture-susceptible. This innovative method, grounded on maximum effective air voids and percentage density change, offers nuanced insights for more accurate moisture resistance assessments. Furthermore, the study explores the effect of effective air void size on moisture damage resistance by image processing for dense and gap-graded gradation of 13.2 NMAS, unveiling clogging behavior especially in dense-graded mixture due to smallest pore size. In conclusion, the study provides an in-depth understanding of asphalt mixture behavior under moisture ingress. By offering a novel approach that integrates multiple parameters and extends beyond the conventional TSR approach, it contributes a practical solution for mitigating moisture damage in asphalt mixtures. This research sets the stage for a potential paradigm shift in the approach to moisture susceptibility assessment, enriching the asphalt field with critical insights.