Assessment of low-temperature cracking in asphalt concrete pavements using an acoustic emission approach

An acoustic emission (AE) approach to evaluate low-temperature cracking susceptibility of asphalt binders and asphalt concrete mixtures is presented. In the approach thin films of asphalt binders were bonded to granite substrates and exposed to temperatures ranging from 15 °C to -50 °C. Differential thermal contraction between granite substrates and asphalt binders induces progressive higher thermal stresses in the binders resulting in the thermal crack formation, which is accompanied by a release of elastic energy in the form of transient stress waves (AE). These AE-based T_cr predictions showed excellent correlations with predictions based upon AASHTO TP1 and with AASHTO MP1A protocols. Similar results were also obtained when asphalt concrete mixtures samples were exposed to temperatures ranging from 15 °C to -50 °C. The AE-based approach for low-temperature characterization of binders and asphalt concrete mixtures is faster and has a lower coefficient of variance than the traditionally used methods based upon the binder rheological properties.