From plant to pavement: field evidence and life cycle assessment insights on reduced-temperature chemical warm mix asphalt

This paper presents results from a full-scale study evaluating the constructability, temperature trends, in-place density, emissions, and environmental impacts of reduced-temperature chemical warm mix asphalt (WMA) in comparison to conventional hot mix asphalt (HMA). Over 2600 tonnes of asphalt were produced and paved over two days, with instrumentation deployed to collect temperature, fuel usage, and particulate matter emissions data. WMA was produced using a chemical additive at temperatures ~26 °C lower than that of HMA. The results showed that WMA had a much lower rate of heat loss during mixture transportation, attained a similar in-place density to HMA, and exhibited 16.83% lower fuel consumption. Additionally, statistical analyses established that particulate matter emissions were significantly lower during WMA production across the monitored locations and emission types. Cradle-to-laid life cycle assessment (LCA) revealed that constructing a pavement with WMA instead of HMA led to savings of 2280 kg CO2 eq. per lane-km of pavement. When scaled for a hypothetical nationwide adoption, annual savings of 456,000 tonnes of CO2 eq. could be achieved, corresponding to offsetting emissions from ~1.87 billion km driven by gasoline-powered passenger vehicles. These findings confirm that reduced-temperature WMA can be successfully implemented in full-scale paving operations and offers an environmentally beneficial alternative to traditional HMA.