Performance Characterization of Recycled Asphalt Pavements with Warm Mix Asphalt Technologies
AdvisorSebaaly, Peter E.
Civil and Environmental Engineering
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This study evaluated the laboratory performance characteristics of Recycled Asphalt Pavements (RAP) with Warm Mix Asphalt (WMA) Technologies. RAP was introduced in mixtures at three levels: 0, 15 and 35% of RAP contents. Five WMA technologies were evaluated against all the mentioned levels of RAP content. The study was conducted in two phases, each phase with a separate aggregate and RAP source. Standard Marshall Mix design method was followed for the mix design purpose, with some modification to introduce RAP and WMA. Rheological properties of both the virgin and recovered asphalt binders were determined. Laboratory designed mixtures were evaluated for moisture resistance, dynamic modulus, rutting resistance and thermal resistance behavior. Moisture resistance of the mixtures were evaluated by performing the indirect tensile strength test for 0 and 1 freeze-thaw cycles. Resistance to rutting was evaluated by determining flow number using the Asphalt Mixture Performance Tester (AMPT) machine. Finally, thermal resistance of the mixtures were evaluated by conducting Uniaxial Thermal Stress and Strain Test (UTSST). The study determined that the moisture susceptibility of the mixtures increased with the increase in number of freeze thaw cycles. Dynamic modulus of the mixtures were higher for a higher RAP content. Further, HMA mixtures were determined to have higher dynamic modulus and tensile strengths than the WMA mixtures. Even though, the strength values for WMA mixtures were lower than the HMA mixtures, WMA mixtures satisfied the required criteria defined by agency. HMA mixtures were found to have higher rutting resistance than WMA mixtures, and this resistance increased with the increase in RAP content. Even though HMA mixtures with higher RAP content performed better in terms of rutting, such mixtures exhibited a huge drop in thermal resistance capacity. Varying aggregate source did not significantly influenced the performance of mixtures, except in the case of rutting. Further study is need in order to validate the use of higher RAP content in the mixtures.