Production of durable mortar for aggressive environments using waste glass aggregates and metakaolin-based blended cement

The depletion of river sand and its environmental consequences, combined with the vulnerability of concrete structures to harsh environments, pose a significant global concern. To mitigate maintenance costs, it’s essential to prioritize sustainable infrastructure production that balances durability and environmental sustainability, particularly in aggressive environments. This study explores the possibility of production of durable mortar for aggressive environments using waste glass aggregates and metakaolin-based blended cement. The waste glass cullets were used as sand replacement at 0%, 50%, and 100% and blended with metakaolin and gypsum to produce binary and ternary mortars. The blend of metakaolin and gypsum was explored to accelerate cement hydration and enhance overall durability of cementitious materials in sulphuric acid environments. Their suitability was assessed by fluidity, flexural strength, compressive strength, split tensile strength, pozzolanicity, chemical resistance, permeable voids and water absorption. Test results revealed an average increase of 3.7% and 23.2% in flexural, 15.6% and 46.8% in split tensile strength, and 4.6% and 28.5% in compressive strength for 50% and 100% waste glass mortar mixes compared to mortar mixes without waste glass cullet. While metakaolin increased initial surface water absorption by 71.8%, it reduced final water absorption by 24.2% and permeable voids by 13.9%. In contrast, gypsum recorded lower initial surface water absorption of 25.1% but significantly increased final water absorption by 97.2%. In addition, increased trend of split tensile, compressive strength and flexural strengths with increasing waste glass cullets were observed which was attributed to interlocking and micro-filler effects of waste glass, its improved bonding with cementitious paste and pore refinement. Also, average deterioration mass ratio of 17.67%, 15.46% and 9.6% was observed for mortars with 0, 50% and 100% waste glass cullets in sulphuric acid. These results attest to the improved sulphuric acid resistance of waste glass cullets compared to river sand and was attributed to lower water absorption, chemical inertness and formation of less permeable hydration products by waste glass cullets. These findings suggest binary metakaolin-blended waste glass cullet mortar with adequate protection for sulphuric acid aggressive environments. © Springer Nature Switzerland AG 2025.