Laboratory Performance Based Cost Assessment of Warm-Mix Asphalt Concrete Technologies

With growing environmental concerns and ever-increasing budgetary constraints, the use of warm-mix asphalt (WMA) is on the rise, since WMA has the potential to reduce cost and provide environmental benefits. One hurdle in the adoption of WMA is the uncertainty of its long-term performance. Currently a literature gap exists on the performance of WMA, as most studies tend to focus on the economics and environmental benefits of the emerging technology. Laboratory experimentation, in the form of rutting, fatigue life, and moisture susceptibility as measured by tensile-strength-ratio (TSR), was conducted on four different WMA technologies in order to compare the change in performance between WMA and hot-mix asphalt. Linear regression models were then fit to the laboratory results to identify variables which were statistically significant in affecting performance. Life cycle cost analysis principles were then applied to compare the warm mix technologies. The resulting dollar amount from the cost analysis was compared with the regression models, which allow for direct comparison between cost savings and performance. The result of this study shows that addition of low and moderate amounts of WMA additive was found to increase fatigue life; however, high dosages of additive negatively affected the fatigue life. It was also shown that reducing the mixing temperature of any asphalt mixture tested in this study increased the likelihood of rutting. Lastly, TSR and fatigue life were found to be dependent on the type of additive chosen. In general, every WMA technology tested has the potential to reduce costs and improve at least one measure of the expected performance of asphalt mixtures.