The effect of fine aggregate angularity on moisture sensitivity and fracture resistance of hot mix asphalt

In this study, the effect of fine aggregate angularity was evaluated using Marshall strength ratio and indirect tensile strength tests on moisture sensitivity, sample failure and cracking capability of hot asphalt mixtures. Two types of Qubit crusher (Mix design-1) and hydro-cone (Mix design-2) were used to prepare fine-grained stone materials for the production of hot asphalt. By comparing the parameters of both designs, the results of this study showed that although the grain size of both sands was the same the angulation coefficient of sand produced in Qubit crusher has decreased by 7% compared to sand produced in hydro-cone crusher, which increases by 1.2% the optimal amount of asphalt mixture. Despite this increase in the optimal amount of bitumen in the asphalt mix of mix design-1, the amount of effective bitumen in this asphalt mix decreased by 1%. The reduction of effective bitumen in the asphalt mixture weakened the bond between the bitumen and the aggregate, and accordingly, the moisture durability and resistance in all failure modes of the asphalt mixture of mix design-1was less than that of the asphalt mixture of mix design-2.