Evaluation of Long-Term Behavior of Warm Mix Asphalt Containing Steel Slag Aggregates and Reclaimed Asphalt Pavement

Recycling Steel slag aggregates into the asphalt mixes improves their performance; however, increasing the bitumen consumption as a result of this recycling bridle its wide spread application. To overcome this difficulty, this research investigates feasibility of concurrent recycling of reclaimed asphalt pavement (RAP) and steel slag into the warm mix asphalt. To this end, six types of asphalt mixture with two coarse steel slag aggregate percentages (0 and 40%) and three RAP contents (0, 20, and 40%) were prepared in two states of aging (short- and long term) and their resistance against rutting, cracking, and moisture-induced damages were examined and compared statistically. Results showed that incorporation of steel slag aggregates and RAP enhances the rutting and cracking performance of mixes; however, the former reduces and the latter one increases the moisture susceptibility. On the other hand, inclusion of RAP and steel slag in mixes respectively degrades and promotes the deformation of asphalt mix at the failure in indirect tension test. Overall, it is proven that simultaneous recycling of steel slag and RAP into the WMA not only is beneficial from economic and environmental perspective, but also leads to a mix which performs better or at least comparable to the conventional mixes and also the mixes that are made with one of these waste materials.