Viscoelastoplastic Damage Characterization of Asphalt–Aggregate Mixtures Using Digital Image Correlation

Abstract

This paper presents the research effort in which the viscoelastoplastic continuum damage (VEPCD) model is developed and calibrated for the behavioral prediction of asphalt–aggregate mixtures subjected to tensile stresses in pavement structures. It is found that the formation of strains in the mixtures becomes highly localized as microcracks densify, coalesce, and further grow to develop into macrocracks. However, conventional linear variable differential transformers (LVDTs) used in most laboratory tests are unable to capture the localized process zone strains [or fracture process zone (FPZ) strains] due to various limitations. Consequently, the VEPCD model, calibrated using LVDT measurements, ceases to accurately predict the performance of asphalt–aggregate mixtures after the strain localization. This study explores the use of a digital image correlation (DIC) technique for measuring the FPZ strains in an aim to extend the validity of the VEPCD model beyond localization. An experimental/analytical methodology that requires transfer from LVDT strains to DIC strains after strain localization for model calibration and validation is presented for a range of loading and temperature conditions.