Environmental impact analysis of geopolymer based red mud paving blocks

Red mud is a by-product from alumina industry. Global production of red mud was around 369 million tons in 2023, and India contributed over 6% of total. Landfilling of red mud may leach out heavy metals to soil and water, which could have negative consequences for the ecosystem. Incorporating the red mud in a geopolymer matrix is a safe option. This paper aims to analyse the environmental impact of the 1.0 m3 red mud containing geopolymer paving blocks using GaBi (Indian extension database) software. The data used for the analysis was generated from the studies conducted in continuous geopolymer pilot plant (10 tons/day). The analysis shows the major contributions from alkali activators and electricity. Red mud paving blocks exhibit global warming potential (275 kg CO2 eq.), human toxicity (51.7 kg DCB eq.), and terrestrial ecotoxicity potential (0.441 kg DCB eq.). Red mud blocks have similar acidification (1.65 kg SO2 eq.) and abiotic depletion potential (fossil) (3080 MJ) on comparison with cement paving blocks. Red mud geopolymer paving blocks offer a sustainable alternative with the reduced environmental footprint compared to conventional methods. Red mud paving blocks seems to be more sustainable than traditional cement paving blocks. Red mud paving blocks exhibit lower global warming (21.6%), human toxicity (50%) and terrestrial ecotoxicity (38.9%) potential compared to cement paver. Abiotic depletion (fossil) and acidification potential are nearly same for both paving blocks.