Life Cycle Assessment for measuring the environmental effects of the manufacture and construction of bituminous mix paving

Abstract

A method to evaluate and quantify environmental impacts due to the production processes of component materials, manufacturing and construction of mix asphalt pavements is presented in this paper. The Kyoto Protocol has introduced new variables in the sustainability analysis of any construction activity as greenhouse-gas emissions. Nevertheless, production of a bituminous mix causes very different environmental consequences depending upon the materials used, typology of the plant and fuel, on-site pouring technique, transport distances and even its possible recycling. The proposed methodology for the environmental analysis and valuation of this construction activity is based on the Life Cycle Assessment (LCA) taking into account all the non-renewable resource consumption, from the extraction and treatment of the primary raw materials, manufacture and transport of the product, to reworking or extinction as a waste, and the potential environment and public health effects during all the lifespan of the product. In addition, the LCA enables us to compare alternative roadbed designs and construction techniques in terms of their environmental impact. All the life cycle phases, inputs (energy and fuel consumption) and outputs (manufactured products, emissions and waste materials) generated are exhaustive compiled and calculated by means of a specifically-developed simple software. The results related to hot asphalt mixes show that the use of mixing plants equipped with co-generating systems makes possible to reduce atmospheric emissions by 25%, and by 85% if making use of natural gas as fuel. Moreover, the filler can multiply by 1000 the CO2-eq emissions. Using Warm Mix Asphalt technologies and Low-Energy Coating techniques, the emissions could be reduced above 50% in comparison with conventional bituminous mixes at high temperatures.