Development of Calculation Tool for Assessing the Energy Demand of Warm Mix Asphalt

Abstract

Warm Mix Asphalt (WMA) technologies allow significant lowering of the production and pavement temperature of conventional Hot Mix Asphalt (HMA) thus reducing the energy demand and greenhouse gas emission in the atmosphere. In order to provide the necessary information on environmental and economical potential of WMA in each specific case these benefits have to be acknowledged in quantitative analysis with a Life Cycle Assessment (LCA) tool. The calculation model, presented in the paper, was developed according to EN ISO 14040 as inventory of energy flow for asphalt production, which is the first phase in developing LCA tool. The calculation involves all the main areas that can be influenced by choosing WMA instead of HMA, including production, paving and compaction of asphalt, mining and/or manufacturing of all component materials and transportation. The amount of used energy and the energy sources were defined for each of the processes allowing to express the results in terms of total energy demand distribution by the energy source or by unit process, which is significant in further calculation of carbon footprint. The case study results present the comparison of asphalt energy consumption for seven different modules. Transportation distances and the construction design were defined as typical for a paving site in Latvia. The results showed 7% to 18% energy gain for the WMA in comparison with the reference HMA and indicated that the asphalt production and paving process depend almost entirely on non-renewable energy sources and changes between different modules in this case mostly affect the use of natural gas.