Concrete waste management decision analysis based on life cycle assessment

Abstract

Malaysia, a developing country has always had a high level of construction activity. While it means economic growth, the waste generated by the construction industry has always posed a problem. Most of the construction waste is made up of concrete. The inert and non-hazardous concrete waste, suffers from weak enforcement provisions and this further escalates it into large scale landfill dumping and illegal dumping. The consequences of improper waste management are potentially alarming. With the rising concerns of waste management and global carbon concentrations, this study aims to evaluate the potential environmental impacts associated with concrete waste materials and to identify the best alternative in managing the concrete waste. A comprehensive life cycle assessment framework is proposed to assess the environmental impacts associated with the upstream and downstream of concrete waste life cycle; from raw material extraction to material processing, distribution to disposal or recycle. This study analysed the life cycle system in three scenarios: Scenario 1 depicts the cradle-To-grave scenario where concrete waste is sent to landfill without treatment and recycling. Scenario 2 and 3 depict the cradle-To-cradle scenarios in which the concrete waste is cyclically recycled into aggregates and reuse as road base material and reuse in recycled aggregate concrete production. With the compilation of a systematic life cycle inventory of relevant energy, fuel, and process emissions as inputs and released carbon emissions as outputs, this study helps in interpreting the environmental impacts of different waste management into a series of quantitative measures for more informed decision making. A construction project case study is modelled and analysed in the life cycle assessment framework to demonstrate the model's applicability. Results from this study suggest that the recycle of concrete waste into aggregates and reuse in recycled aggregate concrete production have the least GHG impact to the environment at 0.094 tCO2. Recycling of concrete waste for road base material emits 0.095 tCO2 and followed by landfilling at 0.139 tCO2. This model intended to be an analysis and decisionmaking tool while embracing sustainable development stewardship.