LAUSR

Abstract This paper investigates the fracture toughness of asphalt concretes reinforced with carbon and kenaf fibers. Pure mode I, pure mode II and mixed mode I/II fracture toughness of reinforced asphalt concretes are measured through SCB (semi-circular bend) tests at a low temperature of −15 °C. Three different lengths (i.e., 4 mm, 8 mm and 12 mm) with three different dosages (i.e., 0.1, 0.2 and 0.3% by mixture weight) of fibers are used to prepare asphalt concretes. Results exhibit that both the carbon and kenaf fibers contribute to the enhancement of the fracture toughness of asphalt concrete, particularly when the proportion of mode I relative to mode II is dominant. However, the effect of carbon fibers is found to be superior to that of the kenaf fibers. Compared to the unreinforced asphalt concretes, the carbon fiber reinforced asphalt concrete shows up to 42% increase in the mode I fracture toughness. Furthermore, as the proportion of shear mode at the crack front of the specimen increases, the positive effect of the carbon and kenaf fibers diminishes. Meanwhile, 8 mm kenaf fibers and 4 mm carbon fibers with the dosages of 0.3% are finally found to be more effective in increasing the fracture toughness of asphalt concrete compared to their counterparts with other lengths and dosages.