Investigating the Effects of Asphalt Aging on the Performance of Asphalt Mixtures Containing Steel Slag Aggregates (SSA)

Use of steel slag in asphalt mixtures has proved to be economically and environmentally beneficial. However, still some aspects of this application need more investigation. This study aimed to investigate the aging effect on some properties of asphalt mixture made by SSA and its comparison with conventional limestone aggregates (LA). Asphalt concrete mixtures with the same binder were made with SSA and LA, and were subjected to different aging conditions. Aging conditions included short-term on loose mixture, and long-term in 2 conditioning times of 5 and 7 days on compacted specimens. Then, the specimens were evaluated by Marshall test, indirect tensile strength (ITS) test, Cantabro abrasion loss test and semicircular bending (SCB) test to evaluate their resistance against rutting, moisture damage, raveling and fracture, respectively. Results reveal that the mixture made by SSA has more Marshall stability, Marshall quotient and ITS, and is more resistant against moisture damage and raveling and has higher fracture toughness and fracture energy than the mixture made by LA. Results also show that aging results in increase of Marshall stability, Marshall quotient and ITS and decrease of flow, moisture damage resistance, raveling resistance, fracture energy and fracture toughness. The effect of aging on the properties was found to vary with the type of aggregates. In general, the mixture containing SSA is less affected by aging than the mixture made by LA. However, for some properties the aging is more effective on the mixture containing SSA.