Mechanical influence of mineral fillers on asphalt mixture cracking behaviourAsphalt Pavements

The role of asphalt modifiers and/or modified fillers on the cracking behaviour of asphalt mixtures is extremely complex and has not been fully explained. To characterize the mechanical influence of fillers on asphalt mixture cracking behaviour it is essential to assess the viscoelastic properties of the mastic. Accurate description of strain evolution and distribution in mastics is essential for revealing significant information on mixtures macroscopic behaviour. In this study, 16 different mastics composed by the combination of four different fillers and four asphalt binders, were evaluated on the basis of test results and their mechanical analyses. The Dynamic Shear Rheometer (DSR) and the Bending Beam Rheometer (BBR) were used to characterize the rheological properties of the different mastics. Their cracking behaviour was investigated using a Modified Direct Tension Test (MDTT). Strain localization and damage distribution were observed using a completely redesigned in-house developed Digital Image Correlation System (DIC) capable of accurately capturing localized or non-uniform stress distributions in asphalt materials. The role of fillers in cracking resistance was quantified, and induced mechanisms due to filler addition were investigated. The effect of hydrated lime was further discussed by comparing test results from hydrated lime filler and test results from limestone and clay fillers.