CONSEQUENTIAL LIFE CYCLE ASSESSMENT OF STEEL SLAG AS BUILDING MATERIAL IN SINGAPORE

Abstract

The building and construction industry is one of the biggest ‘culprits’ of environmental issues due to its extremely high demand for raw materials. The frequent extraction of raw materials has led to a huge increase in greenhouse gas emissions over the recent years. There is a cause for concern as the increase in concentration of greenhouse gas emissions can potentially result in adverse environmental impacts such as global warming and climate change. Therefore, researchers around the world have been actively studying the possibilities of replacing the natural raw materials with environmentally friendlier alternatives. Steel slag is an alternative non-natural material with possible utilization as a building material. Steel slag, which has been previously considered a ‘waste’ product and disposed of in landfills due to the lack of utilization, could potentially be used to replace sand as the fine aggregate in concrete for building works. However, before any replacement is carried out, an environmental impact assessment should be carried out first to compare the environmental friendliness of steel slag and the material it is intended to replace, sand. Therefore, this research fulfills the research need with the conduct of a CLCA on steel slag and serves as a guide for industry professionals regarding the selection of steel slag as a building material. The CLCA will analyze and evaluate the environmental impacts associated with the different life cycle stages of sand and steel slag, so as to obtain the basis for comparison. The quantitative data needed for the CLCA was obtained from industry sources, and from two widely used LCA databases, GaBi and EcoInvent. To identify the consequences of replacement, two possible scenarios based on the current levels of consumption of sand and production of steel slag were simulated. The findings suggest that replacement of sand with steel slag will result in greater environmental impacts, with values across impact indicators ranging from 0.4 times lower to 264 times greater. Based on data collected through questionnaires, a qualitative analysis was conducted as there are significant benefits of steel slag usage regardless of its environmental impacts, such as reduction of reliance on foreign imports and landfill demand.