Fatigue Characterization of Foamed Asphalt by Simplified Viscoelastic Continuum Damage (S-VECD) Analysis

摘要

In asphalt foaming process, water is added into the hot asphalt binder at high air pressure to create foam in the binder. The added water, also termed as foaming water content (FWC), turns into water vapor and get encapsulated into the binder in form of numerous water bubbles during the foaming process. These water bubbles are expected to be evaporated out of the foamed warm mix asphalt (WMA) during mixing and compaction. However, all the bubbles may not be completely evaporated out, rather some of the bubbles might be entrapped in the foamed WMA even after compaction. These residual waters might contribute to damages characteristics of the foamed WMA. To this end, this study determined the effects of foaming on fatigue damage characteristics of foamed WMA. Foamed asphalt binders were designed by varying FWCs and they were tested using linear amplitude sweep (LAS) test. The simplified viscoelastic continuum damage (S-VECD) modeling of the LAS test data were utilized for the damage evaluation. The study reveals that foaming softens the binder, which results in slightly lower stiffness, however, an equivalent or slightly improved fatigue characteristics compared to the regular unfoamed binder.