A Study on Warm Mix Asphalt Sustainability

Together with harmful gas emissions, energy consumption is generally regarded as the main issue in environmental policy. The benefits of reducing energy demand are not only related to lower environmental problems (energy production and usage can be associated with air and water pollution, climate change, and solid waste disposal) but are also closely linked to the reduction in the price of road construction and rehabilitation. To this end, the reduction of the amount of energy required at the production stage is gaining momentum. Based on the above, the objective of this study is to investigate the energy required throughout the process of construction of a friction course paved using warm mix asphalt (WMA) technology and including recycled and waste products in the mixture. Energy impacts (in terms of global energy requirement - GER) are assessed through the main processes from the cradle (acquisition of raw materials) to the gate (friction layer construction included) using a life-cycle method and focusing on the asphalt mixture production stage. Finally, results are compared to conventional hot mix asphalts (HMAs). The processes are investigated in order to identify the life-cycle stage and the processes associated with the highest impacts. The main results show that the energy requirement for the solution that includes HMA is approximately 1.2 times higher than that of the alternative that uses WMA. In particular, because of the higher mixing temperature, the production of the HMA mixture requires an amount of energy that is greater than that demanded for the WMA solution.