Evaluating Low-Temperature fracture toughness of steel slag Aggregate-Included asphalt mixture using response surface method

[Display omitted] •Low-Temperature Fracture Toughness of SSA-Included Asphalt was investigated.•ENDB specimen was employed to evaluate Mode I&II fracture toughness.•At 0 °C, using only coarse SSA yielded higher fracture toughness.•At 0 to −24 °C, a combination of fine and coarse SSA showed better fracture toughness.•In both modes I and II, crack path growth was parallel to the applied load in ENDB specimen. This study is aimed to evaluate the low-temperature (0 to −24 °C) fracture toughness of fine and coarse (0–50 % and 0–100 % inclusion) steel slag aggregate (SSA)-included asphalt mixtures in different Modes (I, II and I/II). To this end, edge-notched disk bend (ENDB) specimens were made and tested under three-point bending in different fracture modes, and response surface method (RSM) was used to evaluate and optimize the low-temperature fracture toughness of fine and coarse SSA-included asphalt mixtures. Results indicated that at temperatures between 0 and −24 °C, to increase the possibility of reaching the maximum fracture toughness, it is better to use a combination of fine and coarse SSAs. Otherwise, the desirability of only inclusion of fine/coarse SSA is significantly lower than simultaneously inclusion of them in terms of fracture toughness. Here, the highest desirability was achieved at 0 % fine SSA, 73 % coarse SSA and 0 and −24 °C.