Warm-Mix Asphalt Trials in New York State: Laboratory and Field Performance

Abstract

Warm-mix asphalt (WMA) technologies have been studied by many researchers over the past 10 years with a majority of the research pertaining to laboratory-prepared materials or sampled asphalt mixtures that are reheated in the laboratory before sample preparation. Unfortunately, the laboratory preparation of WMA, especially foamed systems, does not do a very good job at simulating the plant production processes. Meanwhile, reheating loose mix that had been sampled during production has shown to stiffen the asphalt mixture owing to additional oxidation aging, thus altering the initial asphalt mixture properties. In addition, the majority of the WMA research studies published contain little to no field performance, making it difficult to know whether or not the differences in material performance observed in the laboratory translate to actual field performance. Research is presented in regard to the laboratory performance of hot-mix asphalt (HMA) and companion WMA mixtures using various WMA technologies. All test specimens were compacted at the asphalt plant’s quality control laboratory to mitigate any issues with reheating. In addition to the initial laboratory testing, field performance of five of the test sections 3 to 4 years after being placed is presented. Comparisons of the performance of plant-compacted and field cores are described, as well as comparisons of the measured field distress and the laboratory performance of the WMA and HMA mixtures. The resulting information has been used to generate a WMA guidance document in New York State.