Mechanical Performance and Embodied Energy Assessment of Geopolymer-Stabilized Earthen Masonry Blocks Incorporating Gold Mine Tailings and Tank Bed Soil

Abstract

Due to its contributions to the emission of greenhouse gases, the depletion of topsoil, and the consumption of non-renewable energy resources, the fired clay brick industry is under considerable scrutiny. The investigation of unfired Geopolymer-Stabilized Earthen Bricks (GSEBs) with binder matrices comprised of Class F fly ash and Alccofine 1203 and alkali activators of 6 M NaOH and Na₂SiO₃ in a 1:2.5 molar ratio, using Tank Bed Soil (TBS) and Gold Mine Tailings (GMT) as the primary aggregates in each brick, revealed that the blocks produced with the optimized mix of Binder:Liquid:TBS:GMT = 1:0.3:1.8:1.2, cured in an oven at 58°C for seven days achieved compressive strengths between 6.8 and 11.3 MPa - values that meet the minimum requirement of 3.5 MPa for first-class masonry blocks and compete with fired clay bricks. Geotechnical analyses of the aggregates and the produced GSEBs are presented. A modified cradle-to-gate assessment produced an estimated embodied energy of 1,150 MJ/m³ under the stated waste-allocation, process-energy and scale-normalized oven-curing assumptions. This value was approximately 54.3% lower than the adopted historical benchmark for burnt-clay brick. The main source of energy for GSEBs is from the synthesis of the alkaline activators of NaOH and Na₂SiO₃ at energy values of 20.5 MJ/kg and 5.37 MJ/kg, respectively. These results indicate that using mine waste to produce GSEBs is an environmentally friendly alternative to conventional forms of masonry construction, especially in areas near the Kolar Gold Fields and thermal power stations.