Comparative life cycle assessment of concrete road pavements using industrial by-products as alternative materials

The construction industry is a major consumer of natural resources and a major contributor to CO2 emissions. As increasing attention is paid to sustainability and resource preservation, current construction practices need to be assessed in terms of environmental performance as well. Currently, the decision making process for pavement construction in Greece is largely based on initial cost, excluding use and maintenance costs as well as environmental performance. Therefore, the use of concrete road pavements is very limited, despite possible technical and financial benefits. In the present paper, a comparative life cycle assessment was carried out for six different concrete road pavements. The parameters for the comparative LCA were three types of binders; a pozzolanic Portland cement, a new hydraulic road binder and a mixed-type binder consisting of Portland cement and fly ash, as well as two different aggregates; crushed limestone and steel slag. Construction, use and maintenance and end-of-life recycling for a period of 40 years were considered for the life cycle assessment. Results show that concrete road pavements with high volume of alternative materials can reduce CO2-eq emissions to a great extent compared to ordinary concrete pavements and, thus, significantly improve their environmental footprint. The transportation distance sensitivity analysis showed that substituting cement with fly ash is environmentally beneficial even when fly ash is transported over long distances, while the emissions from the use of alternative aggregates in concrete are reduced only in limited geographical areas.