Integrated policies to promote sustainable use of steel slag for construction—A consequential life cycle embodied energy and greenhouse gas emission perspective

Abstract

Steel slag is a by-product of steelmaking and is usually disposed of in landfills. Recent development in sustainable concrete saw the use of steel slag as a replacement for sand in concrete mixture. This study applied attributional and consequential life cycle assessment to deduce the net environmental impacts – measured in terms of global warming potential and embodied energy – due to replacing sand with steel slag. It was found that, considering both mass and economic allocation methods, steel slag generally has more negative life cycle environmental impacts. However, by considering three likely consequences of this material replacement (resulting in changes in international trade in sand and steel slag) and that certain sustainable steelmaking technology innovations were adopted, it was found that such a replacement may result in a net reduction in environmental impacts. To ensure that this material replacement results in lower global warming and also ensure resource security, a mathematical expression was derived that enables us to estimate how much Singapore's sand trade has to change. To apply lessons learnt from these assessments to integrated sustainability policymaking, the environmental, economic and social related challenges were discussed and possible solutions proposed.