Hybrid input–output life cycle assessment of warm mix asphalt mixtures

• The WMA technology is able to significantly save energy and GHG emissions.
• 20% of savings can be reached with the WMA technology.
• The wax slightly offsets the benefits of the WMA technology.
• Fuel, mining and construction sectors are the major contributors to the impacts.
• The fuel consumption in all the supply chain should be optimized.

One of the most important challenges facing our society is the efficient and economic use of energy, and with it the corresponding need to reduce greenhouse gas (GHG) emissions. Due to growing concerns over global warming and climate change in recent years, warm mix asphalt (WMA) has become an important new research topic in the field of pavement materials, as it offers a potential solution for the reduction of energy consumption and GHG emissions during the production and placement of asphalt mixtures.While many studies have been conducted to demonstrate that the mechanical properties of such mixtures are not significantly affected, many questions and concerns regarding the environmental benefits they offer have yet to be addressed. In this study, a comprehensive hybrid life cycle assessment of WMA production was carried out to accurately evaluate and quantify the potential benefits of WMA technology by assessing the environmental impacts of its production associated with energy consumption and GHG emissions.The results of this study show that, for the WMA mixtures considered here, when the upstream supply chain related to the production of the materials composing such mixtures is taken into account, WMA technology is able to significantly save energy and reduce GHG emissions when compared to the control mixtures. However, it must be noted that in some cases, the manufacturing temperature at the asphalt plant must be reduced before the benefits of reduced emissions and fuel usage can be obtained. The results of a detailed production layer decomposition indicate that the fuel, mining and construction sectors are the main contributors to the environmental impacts of manufacturing the WMA mixtures studied.