Laboratory Evaluation of Recycled Asphalt Pavement Material in Warm-Mix Asphalt

This research study focuses on results from laboratory tests on Warm-Mix Asphalt (WMA) mixtures prepared using two methods—Evotherm® 3G additive and “The Foamer” device by Pavement Technology Inc.—with varying percentages of Reclaimed Asphalt Pavement (RAP). The resulting mixture combinations were evaluated in the laboratory for their performance characteristics and compared with a control Hot Mix Asphalt (HMA) with the same amount of RAP. Tensile Strength Ratio (TSR) was used to evaluate the moisture susceptibility. Dynamic modulus (|E*|) tests were conducted to obtain master curves for all mixtures. They were also used to compute the |E*| Stiffness Ratio, i.e. the ratio of dynamic modulus values of moisture-conditioned specimens to that of unconditioned specimens, analogous to the Tensile Strength Ratio. Only the Foamer mixture with the highest amount of RAP did not pass the TSR test. No correlation was found between TSR and |E*| Stiffness Ratio. Despite lower production temperatures, WMA-RAP mixtures show similar |E*| behavior to HMA-RAP. Thus, WMA technologies can be used to help incorporate higher amounts of RAP rather than using a softer virgin binder grade in high-RAP HMA.