Laboratory Evaluation of Water Bearing Additive for Warm Mix Asphalt

Benefits of warm mix asphalt (WMA) technologies in terms of energy savings and air quality improvements are highly promising. However, further investigation is needed to validate their performance as laboratory and field data are significantly lacking for conditions in Oklahoma. To this end, effects of varying dosages (4, 6 and 8% by the weight of the binder) of a water-bearing WMA additive, Advera®, on the performance grade (PG) of a local binder, PG 64-22, were evaluated. The effectiveness of a commonly used amine-based liquid anti-stripping (AS) agent in Oklahoma, AD-here® HP Plus, on the WMA-modified binder was also studied. Furthermore, the effect of reduced oxidative aging on Advera®-modified binder was investigated. The optimum dosage of Advera® was found to be 6% (by the weight of the binder), which did not alter the PG grade of the base binder. A fairly small amount (0.5% by the weight of the binder) of the AS agent was found to be effective in increasing the fatigue fracture and low temperature resistances of the WMA-modified binder. A slight reduction of the high PG temperature was observed when a reduced oven temperature was maintained during short-term aging of the Advera®-modified binder. Selective performance test data of a corresponding WMA mix from a closely related study was found to consistent with the rheological properties of the modified binder. The findings of the current study are expected to enhance the inventory of rheological database for local materials and help in implementing WMA mixes in Oklahoma.