Comparison of asphalt binder and mixture cracking parameters

Cracking is one of the most prevalent types of distresses in asphalt pavements. There are different cracking index parameters that are determined from tests conducted on binders and mixtures to assess cracking potential. The objective of this study is to compare binder and mixture parameters and evaluate the similarities and differences between the rankings and values obtained. This study includes binder and mixture testing on 14 plant-produced mixtures including 3 different binder grades, 3 binder sources, 3 aggregate gradations, and mixtures containing a range of reclaimed asphalt pavement and/or recycled asphalt shingles contents. Testing included PG grading and 4 mm dynamic shear rheometer testing on the extracted and recovered binders that were long-term aged. Mixture testing included complex modulus, simplified viscoelastic continuum damage (SVECD) fatigue, and disc-shaped compact tension testing on short-term-aged mixtures. Parameters evaluated included high and low PG temperatures, ΔTcr, Glover–Rowe parameter (binder and mix-based), R value, dynamic modulus, phase angle, number of cycles to failure from SVECD and layered viscoelastic critical distresses analysis, and fracture energy. The results show that generally the binder parameters correlate well with each other but the mixture parameters do not. Good correlation was observed between binder and mixture stiffness-based parameters, but there was generally low correlation observed between binder and mixture cracking parameters for the mixtures evaluated in this study, possibly a result of differences in ageing level. Recommended future work includes non-linear statistical analysis, incorporation of field performance, and testing on long-term-aged mixtures.