Study on mechanical and durability properties of alkali modified metakaolin coarse aggregate in lightweight geopolymer concrete

Abstract

Geopolymer Concrete (GPC) is emerging as a sustainable alternative newlineto traditional Portland cement concrete, leveraging industrial by-products to newlineminimize environmental impact. The proposed thesis investigates the newlinemechanical, durability, microstructural, bond-slip, and reinforced concrete newline(RC) beam behavior of geopolymer concrete (GPC) incorporating Metakaolin newlineCoarse Aggregate (GMCA) and Natural Coarse Aggregate (GNCA). The newlineresearch emphasizes the enhancement of performance that is achieved by using newlineGMCA in place of conventional GNCA. The study highlights the benefits of newlineGMCA as a sustainable and lightweight alternative to the traditional aggregates newlinethrough comprehensive experimental and analytical methodologies. newlineThe mechanical properties of GPC were evaluated based on density, newlinecompressive strength, tensile strength, and flexural strength. Density newlinemeasurements under fresh, dry hardened, air-dried, and oven-dried conditions newlinerevealed that GNCA mixes had consistently exhibited higher densities newlinecompared to GMCA mixes, owing to the higher bulk density of natural newlineaggregates. In fact, fresh densities are ranged from 2353 2360 kg/m³ for newlineGNCA and 1820 1827 kg/m³ for GMCA. The specified lightweight nature newlinestems from the lower bulk density (1071 kg/m³) and higher water absorption of newlinemetakaolin aggregates. Compressive strength tests conducted on GNCA and newlineGMCA mixes with L/B ratios of 0.4, 0.45, and 0.5 at curing ages of 7, 28, and newline90 days demonstrated that GMCA mixes had consistently achieved higher newlinecompressive strengths. In the study the GMCA0.4 mix had showed the highest newlinestrength, surpassing GNCA0.4 by 2.58%, 2.28%, and 2.18% at 7, 28, and 90 newlinedays, respectively. newline