Investigating the Marshall and Volumetric Properties of Asphalt Concrete Containing Reclaimed Asphalt Pavement and Waste Oils Using Response Surface Methodology

This research aimed to use response surface methodology (RSM) for investigating the Marshall Stability (MS), flow and Voids in Mineral Aggregates (VMA) of asphalt concrete containing different percentages of Reclaimed Asphalt Pavement (RAP) and rejuvenated by different percentages of waste cooking and engine oil. Variables of RAP content in 3 different levels of 25, 50 and 75% (by the weight of total aggregates) and waste oils content in 3 different levels of 5, 10 and 15% (by the weight of total binder) were selected. Quadratic and linear two factor interaction models were well fitted to the experimental results. Analysis of variance showed that the models were capable to well predict the MS, flow and VMA of the mixtures, and the terms of oil and RAP content and type of oil are significant. MS, flow and VMA increased with increasing RAP content and decreased with increasing oil content. Results also reveal that higher MS, flow and VMA values are resulted by using WEO than using WCO. Some interaction effects were found between RAP content, oil content and type of oil on the responses. Optimization analysis showed that using 10.6% of WCO and 15% of WEO, allows a maximum RAP incorporation of 75 and 51.77%, respectively, by which the properties are similar to control mix. Use of the rejuvenators allows using high RAP content without sacrificing the properties of the mixtures.