Environmental Comparison at Industrial Scale of Hot and Half-Warm Mix Asphalt Manufacturing Processes

Both half-warm and warm mix technologies allow reducing the use of fossil energy sources (fuel, natural gas) in mixing plants, yet in different proportions, as reported in the technical literature. In this study, a half-warm mix process called LEA® will be assessed by means of measurements at the plant as well as during actual road works, within the framework of a Life Cycle Assessment. Inventory fluxes and environmental impacts were both determined for hot mix and half-warm mix asphalts. This paper presents the environmental comparison drawn between the consumption and pollutant fluxes of hot and half-warm mix asphalt produced by the same plant and laid on the same heavily-traveled road section near Paris (France). The experimental program was jointly conducted by three partners: the road owner, the road contractors, and an independent organization responsible for performing environmental assessments. This experiment reveals a positive contribution from the half-warm-mix process in reducing all calculated indicators, in comparison with the hot-mix process, thereby confirming previous studies on predicted energy savings yielded by theoretical models. Results from this study however need to be completed by an inventory of environmental data on additives, and a mechanical behavior assessment of the two pavements types over a relevant service period.