Evaluation of WMA Technologies and Recycled Asphalt Pavement on Nevada Aggregates

Nevada Department of Transportation (NDOT) is currently experimenting with warm mix asphalt (WMA) technologies and recycled asphalt pavement (RAP). The purpose of this experiment is to evaluate the effects of various WMA technologies and various levels of RAP on Nevada mixtures using current Superpave WMA and RAP design techniques. This part of the project evaluated aggregates from Lone Mountain, Rinker, North Tenaya, and Sloan. Advera, Evotherm 3G, and Sonnewarmix, were the WMA technologies evaluated, while plant foaming mixtures will be evaluated at a later time. It was decided that two levels of RAP would be evaluated; one level found through the use of a traditional blending chart and one through a new method known as the mortar experiment. It was also decided that samples mixed at 0.2 percent below optimum binder content (OBC) would be compared to OBC samples. The mortar experiment determined levels of RAP binder replacement for Lone Mountain and Rinker aggregates much lower than the blending chart. The levels were 17 percent and 39 percent, respectively. A mix was successfully designed and tested with 15 percent RAP binder replacement with favorable results; a mix with 35 percent RAP binder replacement will be designed and tested in the near future. It is suggested that further research should be conducted on the mortar method to explore minimization of variables during the experiment. Samples at 0.2 percent binder below the OBC performed comparable to samples at OBC. It is suggested that further analysis of coating and compactability should be performed on the evaluated mixtures as per Superpave WMA standards. As expected, mixes with WMA performed well in resistance to moisture damage and reflective cracking, but did not perform as well in resistance to rutting tests. Mixtures with RAP behaved the opposite; good resistance to rutting but not as good resistance to moisture damage and reflective cracking