Abstract
Open-graded friction course (OGFC) is a mixture with gap-graded aggregate that is used in pavement surfacing. This research proposes methods to improve the durability and structural contribution of OGFC mixtures through laboratory performance testing. A draindown test, a Cantabro test, a permeability test, and an indirect tensile strength test were used to evaluate the performance of OGFC mixtures. The main parameters of this research specify optimum bitumen and desirable air voids, maximum reduction of draindown and abrasion loss, and retained tensile strength ratio. It was observed that the effect of fiber in both states on bitumen percentage caused increased sensitivity to oxidation of the asphalt mixture; however, the effect of nanosilica on the reduction of sensitivity to oxidation was considerable. The effect of glass fiber in enhancing tensile strength was far higher than that of basalt fiber. In both states, nanosilica caused improved tensile strength of the mixture. Additionally, the moisture sensitivity of the OGFC mixtures with glass fiber was far better than that of the basalt fiber, and addition of nanosilica caused further improvement. The results showed a negative effect of the addition of basalt fiber alone in the asphalt mixture with a higher between percentage, necessitating the addition of nanosilica in conjunction with basalt fiber.