Comparative life cycle assessment of railway subballast layer with natural and coal overburden aggregates in India

PURPOSE: Coal mine overburden is a term typically used to refer to the waste rocks and the soil materials generated from the open cast method of coal extraction. Previous investigations have found that recycled aggregates from coal overburden are suitable as subballast material in railway trackbed. But no study has been reported yet that analyzes the environmental consequences of this option using the life cycle assessment (LCA) technique. To ensure sustainability, it is vital to examine the environmental consequences of alternatives which is performed in this study. METHOD: The present study compares the environmental impacts of processed aggregates from coal mine overburden with that of natural subballast material. The study also investigates the environmental sustainability of using geocell-reinforced overburden aggregates (GOBA) in the subballast layer. The database used for this LCA study is Ecoinvent 3 database and the impact assessment method adopted is IMPACT 2002 + method. The effects on 15 midpoint indicators and four endpoint indicators along with the contribution of each of the processes involved in the production toward the categories are presented in this study. RESULTS: According to the findings, when compared to natural aggregates, processed aggregates from overburden lower the potential for climate change by 35% and the demand for non-renewable energy by 33%. Furthermore, the production of geocell-reinforced OB aggregates reduces the potential for climate change by 16%. CONCLUSIONS: Based on the IMPACT 2002 + method used in this study, the use of OB aggregates in the track bed's subballast layer significantly lowers the negative effects on human health, climate change, ecosystem quality, and resources and reduces the impacts on all midpoint category indicators. Lastly, the obtained results can be a major support in advancing the resourceful management of coal overburden and the conservation of natural aggregate sources.