Evaluation of Low- and Intermediate-Temperature Cracking Performance of Fiber-Reinforced Asphalt Mixtures

Abstract

This study was conducted to assess the impact of aramid fiber reinforcement on the fatigue and thermal cracking performance of asphalt mixtures at intermediate and low temperatures, respectively. The study also involved evaluating the experimental consistency and ranking fiber-reinforced asphalt mixtures (FRAMs) based on their performance. One aggregate (diabase stone), one binder type (PG 76-22), and two combinations of aramid fibers, added at different dosages, were used to produce three FRAMs. These fibers included polyolefin/aramid (PFA) fibers at 0.05% dosage by mix weight and Sasobit-coated aramid (SCA) fibers at 0.01% and 0.02% dosages. An unreinforced (control) mix was also produced without any reinforcement. All mixtures were produced at a batch plant by keeping their binder content constant (at 5.5%). The manufacturer recommended dry and wet mixing times were used for better fiber distribution and represent actual mixing conditions. The laboratory performance of plant-produced FRAMs was assessed to characterize the low- and intermediate-temperature cracking performance. The indirect tension asphalt cracking test, semi-circular bend test, three-point bending beam tests, and uniaxial fatigue tests were performed at intermediate temperature; the disk shape compact tension test and thermal stress restrained specimen test tests were performed at low temperature. Fibers were successful at improving the fatigue cracking of asphalt mixtures based on intermediate-temperature testing results. In addition, fiber reinforcement, regardless of dosage and combination, showed improvements in low-temperature (thermal) cracking performance. Furthermore, based on ranking analysis for selected performance indicators from each experiment, the SCA 0.02% reinforced mix on average showed the highest cracking resistance.