Evaluating the impact of fiber type and dosage rate on laboratory performance of Fiber-Reinforced asphalt mixtures

The purpose of this study was to evaluate the impact of fiber types, binder content, and their dosage rates on the volumetric properties and laboratory performance of asphalt mixtures. One asphalt mixture (control) and three fiber types (Basalt, Fiberglass, and Carbon) were used. Two different fiber dosage rates were considered 0.15% (recommended dosage rate) and 0.30% by total mixture weight. Furthermore, a novel experimental methodology was developed and implemented consisting of a volumetric mixture design and performance testing—Indirect Tensile Asphalt Cracking Test (IDEAL-CT) and Asphalt Pavement Analyzer (APA)—to isolate the effects of fiber types and dosage rates from the effect of binder content. Statistical analysis was also used to further evaluate the impact of fibers on mixture performance. Results showed that 0.15% dosage rate had little to no impact on optimum binder content, whereas 0.30% dosage rate required an increase in binder content of 0.6%, 0.6%, and 0.8% for basalt, fiberglass, and carbon fibers, respectively, to meet the volumetric requirements. This study showed that the need for additional binder content at 0.30% dosage rate could be due to an increase in specimen volume (referred to as rebounding height) that occurred after 24 h of specimen cooling at room temperature. Performance testing showed that 0.15% (regardless of fiber type) had no impact on cracking and rutting performance. At 0.30% dosage rate, only carbon fiber improved cracking performance without the use of additional binder. Overall, the study highlighted laboratory performance benefits and challenges of using fiber-reinforced reinforced asphalt mixtures.