Performance of Warm-Mix Asphalt Mixtures Containing Recycled Coal Ash and Roofing Shingles with Moist Aggregates for Low-Volume Roads

The objective of this study was to evaluate the laboratory moisture and rutting susceptibility of low-volume hot-mix asphalt (HMA) and warm-mix asphalt (WMA) mixtures containing moist aggregates and recycled materials such as manufactured roofing shingles and coal ash. The test properties of these mixtures included indirect tensile strength, tensile strength ratio, flow value, and rut depth of dry and wet specimens. The experimental design included two percentages of coal ash (10% and 5% by weight of the aggregate), two shingle contents (5% and 3% by weight of the aggregate), three WMA additives (Aspha-Min, Sasobit, and Evotherm), and two aggregate sources. Thirty-two mix designs were performed, and 256 specimens were tested. Test results indicated that the aggregate source significantly affected moisture and rutting resistance regardless of WMA additive or recycled material type. In addition, dry and wet rut depth values of low-volume mixtures containing moist aggregate generally satisfied the demand of pavement performance without requiring additional treatment. Moreover, the addition of WMA additives in low-volume mixtures was effective and generally showed a similar rut resistance to HMA. The utilization of recycled coal ash and roofing shingles significantly improved moisture and rutting resistance of HMA and WMA mixtures.