Pathways for decarbonization of reinforced concrete through rebars based on steel scrap

Abstract

Steel reinforcement bars are an essential structural material in construction and a significant source of greenhouse gas emissions. The review of published environmental production declarations (EPDs) based on India-specific life cycle assessment (LCA) shows considerable variability due to differences in technologies, electricity mixes and scrap sourcing. A case study has been conducted with primary data-driven cradle-to-gate LCA of a scrap-based electric induction furnace (EIF) rebar facility in Tamil Nadu, India. The functional unit is 1 tonne of steel rebar covering raw material supply (A1), transportation (A2), and manufacturing (A3), modelled using SimaPro with EN 15804 indicators. The baseline configuration from the case study, using 98 % scrap steel (entirely imported via sea route), 71 % grid electricity, and 29 % renewable electricity, resulted in a global warming potential (GWP) of approximately 1010 kg CO2-eq./tonne, with manufacturing contributing about 61 % and transportation 27 %. Replacing imported scrap with locally sourced scrap could reduce the global warming potential (GWP) by more than 20 %. Furthermore, increasing renewable electricity to 70 % could lower emissions by 34–50 %, to about 516 kg CO2-eq./tonne. The results suggest that renewable integration and local scrap sourcing are key near-term mitigation strategies, with long-term reductions driven by electricity sector decarbonisation. Further, cases of reinforced concrete indicate that the GWP can be brought down from 700 kg CO2-eq./m3 to 425 kg CO2-eq./m3 with rebars having recycled steel content in a blended binder concrete, and even lower by improving the steel production process.