Volume 39, Issue 3 (May 2011)
Evaluation of Warm Mix Asphalt Mixtures Containing RAP Using Accelerated Loading Tests
This paper presents the results of a study that was conducted to evaluate the performance and constructability of warm mix asphalt (WMA) mixtures containing reclaimed asphalt pavement (RAP). Four sections were constructed at the indoor Accelerated Pavement Loading Facility at Ohio University. Aspha-min, Sasobit, and Evotherm WMA mixtures were used in the wearing course layer of the first three sections. In addition, the fourth section had a conventional hot mix asphalt (HMA) mixture, which was used as a control. Temperature was monitored during the production, placement, and compaction of WMA and HMA mixtures. Furthermore, emission tests were conducted at the asphalt plants during the production of each of the evaluated mixtures. Falling weight deflectometer (FWD) and rolling wheel tests were conducted at different temperatures on all evaluated sections. The results of this study showed that emissions were reduced during the production of the Aspha-min and Sasobit WMA mixtures by at least 50 % for volatile organic compounds, 60 % for carbon monoxide, 20 % for nitrogen oxides, and 83 % for sulfur dioxide, when compared to the control HMA mixture. In addition, although WMA mixtures were produced and compacted at much lower temperatures, they achieved better field densities than the control HMA mixture. The FWD test results showed that at 40°F (4°C) test temperature, the control HMA mixture had significantly lower stiffness than that of the WMA mixtures. However, the FWD stiffness measurement of the HMA and the WMA mixtures were statistically indistinguishable at the intermediate and high test temperatures of 70°F (21.1°C) and 104°F (40°C), respectively. Finally, the rolling wheel test results indicated that the three WMA sections, especially the Evotherm section, exhibited more rutting than the control HMA section during the post primary compaction stage. However, the rutting rate of the HMA section was higher than those of the WMA sections in the secondary stage, which suggests that the rutting difference may slowly be mitigated.