Evaluation of Fiber-Reinforced HMA Mixes’ Performance in North Dakota

Extreme temperature variations between winters and summers are part of life in North Dakota. Looking for materials and methods to modify hot asphaltic mixes to cope with such temperature extremes and improve pavement performance is a never-ending pursuit. The objective of this study was to evaluate the rut-resistance, low-temperature cracking resistance, and fatigue cracking resistance performances of fiber-reinforced HMA pavements compared to conventional mixes. The asphalt pavement analyzer (APA), disk shaped compact tension (DCT), and semi-circular disk shape (SCB) equipment were used to test the samples for rutting, low temperature cracking, and fatigue cracking resistances, respectively. At least four samples for each test were prepared at 7±1% air voids. Three sets of test results were obtained for both the fiber-reinforced and the conventional mixes: APA’s rut resistance (in millimeters); low-temperature cracking results as fracture energy (Joules/m²) at maximum loading (in kN); and SCB’s fracture energy results (Joules/m²) at max loading (in kN) as well as the flexibility indices. The average rut resistance of the fiber-reinforced samples improved by 3%. Fatigue cracking results processed by the University of Illinois Urbana-Champagne’s FIT software increased by 82% over the conventional results. Even though fracture energy results for both fiber-reinforced samples and conventional samples met the criterion for high-level traffic, the DCT’s fracture energy results of the fiber-reinforced samples were lower than the conventional results by 20%.