Asphalt mixtures emission and energy consumption: A review

The objective of this paper is to assess carbon dioxide emissions and energy consumption for the production of road pavements by means of a literature review. The construction of the main types of pavements requires energy and generates greenhouse gas emissions that impact the environment. Different types of asphalt mixtures such as cold mixtures, warm mixtures, asphalt rubber mixtures and mixtures with reclaimed asphalt pavement were assessed. The fuel used in the burners that heat and dry the aggregates is the main source of emissions. Also, the aggregates moisture content is an important parameter that influences the energy consumption. On the other hand, the energy consumption and emissions to produce Portland cement mixtures are related to the process of cement production. For both asphalt and Portland cement mixtures, the extraction, manufacturing and placement were also evaluated. Moreover, the energy consumption of the pavements structures was evaluated. Pavements composed of Portland cement concrete consume more energy than hot mix asphalt. But, warm mix asphalt technologies can save 20–70% of the energy consumption when compared to hot mix asphalt, mainly due to the temperature reduction in the warm mix processes. In addition, the emissions caused by different fuels used to produce pavement mixtures were compared. Asphalt mixtures and their alternative technologies consumed less energy and emitted fewer gases than Portland cement mixtures. Carbon dioxide emissions for hot mix asphalt and asphalt rubber mixtures can be 70% lower than emissions for Portland cement concrete. Some alternatives to reduce energy consumption and greenhouse gas emissions in asphalt mixtures production are the decrease of aggregates moisture content, reduction of the asphalt mixtures production temperature and use of waste materials in pavement construction. Switching from hot mix to warm mix technologies would reduce the carbon footprint generated by the asphalt industry.