Sustainable Geopolymer Paver Block Using Waste Foundry Sand

The construction sector contributes to 8% of global CO₂ emissions, primarily from Portland cement production, which emits around 900 kg of CO₂ per ton of cement. Excessive mining of river sand, with an annual demand surpassing 50 billion tons, depletes natural resources and causes severe ecological damage. This research investigates the utilization of waste foundry sand (WFS) as a sustainable fine aggregate substitute in geopolymer paver blocks, thereby reducing dependence on conventional resources and promoting the circular economy. This research seeks to evaluate the durability and mechanical properties of geopolymer paver blocks that replace M-sand with varying percentages of foundry sand (0%, 15%, 30%, 45%, 60%, 75%, and 100%). Experimental assessments were performed to assess the performance of paver blocks, encompassing abrasion resistance, flexural strength, compressive strength and water absorption. The results revealed that a 45% substitution of foundry sand yielded the greatest compressive and flexural strength, validating its appropriateness as a construction material. Water absorption was maintained at an acceptable level of 1.8%, rendering it appropriate for regions that have high rainfall. Abrasion tests revealed that WFS-based paver blocks observed a weight loss of 23.06 g, indicating enhanced durability under traffic loads. This project facilitated waste valorisation and diminished landfill accumulation by integrating industrial by-products, addressing the annual disposal of 13 million tons of foundry sand. The incorporation of WFS in geopolymer concrete reduced the carbon footprint by 40%, offering a more sustainable alternative to traditional construction materials.