Crack Propagation Parametric Assessment of Modified Asphalt Mixtures Using Linear Elastic Fracture Mechanics Approach

Abstract

Abstract The main objective of this study was to deduce and assess crack propagation parameters of twelve asphalt mixtures including: eight conventional dense graded, two polymer-modified gap graded, and two asphalt-rubber gap graded mixtures using the EN 12697-44:2010 based monotonic semi-circular bending (SCB) test. The asphalt mixes were prepared using different binder types, binder contents, and air voids levels totaling 72 samples with two replicates per mix type. Dense graded mixes had higher fracture toughness than rubber- and polymer-modified mixes at various temperatures. Total fracture energy and residual energy were higher for modified mixes than dense mixes. The share of residual energy in rubber-modified mixtures was 80 % of total fracture energy, indicating that even though a crack initiates in these mixes, it will take much more time to completely fail those materials. Predictive models for crack propagation parameters were developed and were based upon material properties. All three models had very good statistical goodness of fit measures (R2adj ≥ 0.80, and Se/Sy ≤ 0.38). Overall, extensive experimentation and analytical methodologies provided a first of its kind comparative understanding of fracture crack propagation mechanism of conventional versus modified asphalt mixtures based on rationally established SCB test technique using a linear elastic fracture mechanics approach.