An Experimental Investigation On The Production Of Geopolymer Bricks Utilizing Industrial Waste Materials For Sustainable Construction

Abstract

The production of conventional masonry units consumes natural resources and often requires energy-intensive firing or Portland-cement-based binders. This experimental investigation evaluates geopolymer bricks produced from industrial by-products, with particular emphasis on red mud, ground granulated blast-furnace slag (GGBS), lime, fly ash, and waste foundry sand. Preliminary lime-pozzolana cube trials were used to screen material combinations. The finalized brick composition comprised 80% red mud, 10% lime, and 10% GGBS, activated using a 2 M alkaline solution prepared from sodium hydroxide and sodium silicate. The binder-to-filler ratio was maintained at 1:5.5, and the specimens were produced by dry mixing, controlled activator addition, moulding, and moisture-retaining thermal curing. Brick performance was evaluated through dimensional, density, water-absorption, compressive-strength, and flexural-strength tests. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for phase and microstructural assessment, while masonry prisms and triplets were tested to examine system-level compression, stiffness, and shear-bond behaviour. The bricks developed average compressive strengths of 5.67, 10.37, and 14.74 MPa at 3, 7, and 28 days, respectively, and average flexural strengths of 0.35, 0.46, and 0.66 MPa. Average dry density was 1620.1 kg/m³, detailed water absorption was 11.12%, prism strength was 3.95 MPa, and mean triplet shear-bond strength was 0.68 MPa. The results demonstrate the technical potential of industrial-waste geopolymer bricks for sustainable masonry construction.