Evaluation of foamed warm mix asphalt with reclaimed asphalt pavement: field and laboratory experiments

Warm mix asphalt (WMA) technology and reclaimed asphalt pavement (RAP) materials have been increasingly used in asphalt paving mixtures due to environmental and cost benefits. Combining WMA and RAP offers more economic and environmental benefits compared to using either alone. To evaluate the combined effect of WMA and RAP, two WMA mixtures with 20% and 30% RAP were produced using water-injection plant foaming, and they were compared with two comparable hot-mix asphalt (HMA) mixtures with 20% and 30% RAP. The four mixtures were paved on I-70 near Eagle, Colorado in May 2013. Laboratory performance properties of plant-produced mixes and field performance of the four test sections after 13, 25, 38 months were evaluated. The research results showed that the effect of water foaming WMA and RAP was not significant on the laboratory performance properties, construction quality and field performance. Thus, water-injection plant foaming WMA could be used to produce WMA mixtures with 20% and 30% RAP at a lower production temperature. These sections will continue to be monitored to evaluate their long-term performance and compare with the laboratory test results.