Comparison of varied specimen geometry for simplified VECD test with pulse-rest period

Abstract

The viscoelastic continuum damage (VECD) model has become one of the promising methods for interpretation of asphalt mixture’s fatigue and damage behavior based on real physical responses, while asphalt mixture performance tester (AMPT) is the current standardized facility used for VECD characterization test. Since there is a trend to reduce the specimen size used in AMPT tests while maintaining the accuracy of test results, this paper investigated AMPT specimens’ geometry effect on VECD tests and the resultant damage characteristic curves when rest period is inserted after each load cycle (pulse-rest). A series of specifically designed dynamic modulus tests and simplified VECD (S-VECD) tests are conducted on three different sample geometries. The results have agreed with existing findings of that, in comparison to standard sizes, small specimen can produce reasonably accurate dynamic modulus master curves at low to medium temperatures, with the variation at higher temperature found to be caused by fluctuation of loading measurement. Remarkably, at both temperatures (12 and 20°C), a reduced size specimen is able to produce reasonably accurate damage characteristic curves either with 0.3s pulse-rest period or without rest period. Else, the small size specimen demonstrates high likelihood of controlled failure location within the measuring range. The results increase confidence of using reduced specimen size for VECD and rest period healing research by AMPT, with benefit of saving significant experimental time and material consumption.