Evaluation of anti-reflective cracking measures by laboratory test

Abstract

A laboratory simulation of load-induced reflective cracking was carried out using Hamburg wheel tracking tester (HWTT). The simulation, compared with some previous fatigue tests, is more reasonable and applicable because, instead of static load, the cyclic dynamic load is applied to the specimens and the test is relatively time and cost saving. The purpose of this study was to evaluate the effectiveness of various stress-absorbing interlayers to retard the development of reflective cracking, including styrene-butadiene-styrene (SBS)-modified asphalt sand concrete interlayer, asphalt-rubber sand concrete interlayer, fibreglass-polyester paving mat interlayer and stress-absorbing membrane interlayer (SAMI). Specimens without any anti-reflective cracking measure were also included to serve as a control. This paper first describes material properties, aggregate gradations and the simulation apparatus. Then, it assesses the effectiveness of different measures to prevent reflective cracking based on laboratory test results. It reveals that asphalt-rubber sand concrete interlayer performed best and fibreglass-polyester paving mat interlayer ranked next, whereas both SBS-modified asphalt sand concrete interlayer and SAMI showed similar and less sound performances compared with the former two under laboratory test environments. However, SAMI may witness an improved field performance due to the limitation of laboratory test set-up and any of the four measures could prolong the fatigue life of the specimens substantially. A finite element model simulation was followed to explain the anti-reflective cracking mechanism and support the HWTT results.