Comparative Analysis of the Impact of Synthetic Fibers on Cracking Resistance of Asphalt Mixes

Cracking is one of the major distresses affecting pavement's serviceability and performance. This structural distress often observed in hot mix asphalt can be accelerated or more extensive in cold regions such as Canada. In recent decades, synthetic fibers have been commonly used to reinforce asphalt concrete. This technology has been shown to have the potential to enhance the structural properties of hot mix asphalt. However, information related to the assessment of the performance of fiber-modified asphalt mixtures at low temperatures is limited. In this study, different sizes and concentrations of three types of polymer fibers (aramids, polyethylene terephthalate, and polyacrylonitrile) are added to conventional hot asphalt mixtures to evaluate their performance at low and intermediate temperatures. A stereomicroscope is used to investigate the dispersion of fibers in the modified asphalt mixtures. The cracking resistance of fiber-reinforced and unmodified asphalt mixtures, meanwhile, is investigated using four-point beam and IDEAL-CT tests. Moreover, indirect tensile strength test results are used to evaluate the low-temperature properties of both modified and unmodified mixtures. It is found that, at the same quantity, shorter fibers have better dispersion compared to longer ones. It is also found that the type of fiber used may influence the volumetric properties of hot mix asphalt. In general, fiber-modified asphalt mixtures are found to exhibit better cracking resistance at all temperatures compared to unmodified ones; however, the improvement is observed to be more significant in modified mixtures featuring polyethylene terephthalate and a high concentration of aramid fibers.