Low temperature performances of fiber-reinforced asphalt mixtures for surface, binder, and base layers

In the present study, the effects of adding fibers and Reclaimed Asphalt Pavement (RAP) on the low temperature performances of open graded asphalt mixtures for surface layer and dense asphalt mixtures for surface, binder, and base layers were investigated. Two different kinds of fibers were used: a combination of aramid and polyolefins fibers were utilized for preparing fiber reinforced porous asphalt mixtures, while polyacrylonitrile fibers were employed for producing conventional dense asphalt mixtures for surface, binder, and base layers. Reference mixtures were made with virgin materials as a benchmark to study the effects of the fibers' addition. Moreover, asphalt mixtures for surface layers composed of 30% RAP and mixtures for binder layers containing 50% RAP were produced to study the combined effects of fibers and RAP on the low temperature's performance. Thermal Stress Restrained Specimen, Uniaxial Tension Stress, and Semi-Circular Bending tests were used to evaluate the response against thermal distresses. The addition of the fibers showed no significant effects on the low temperature strength, while a remarkable improvement in the failure temperature and crack propagation resistance properties was found. The use of fibers has also shown to be beneficial in combination with mixtures designed with RAP and higher binder content suggesting a dedicated study on mix design for future research.