Effect of pretreated waste glass sand on comprehensive performance of concrete based on mechanical properties, durability, and microstructure

This study investigated the effects of waste glass sand (GS) pretreatment on the mechanical properties, durability, and microstructure of concrete. Concrete specimens were prepared using natural sand (NS), untreated GS, and pretreated GS (TS) as 100 % fine aggregate replacements. The mechanical properties, including compressive strength, flexural strength, direct tensile strength, and static and dynamic moduli of elasticity, were evaluated. Additionally, the durability, such as drying shrinkage, freeze-thaw resistance, rapid chloride permeability, and accelerated carbonation resistance, were analyzed. The results indicate that TS enhances the interfacial bonding by modifying the smooth surface and angular shape characteristics of GS, thus improving the mechanical properties of concrete by 28 % at the maximum. The characteristics of GS contribute favorably to the pore structures for reducing drying shrinkage and enhancing freeze-thaw resistance. Furthermore, calcium silicate hydrate (C-S-H) formed via pozzolanic reactions enhances the chloride penetration resistance and long-term carbonation resistance of GS-containing concrete. Conversely, the C-S-H reaction products on the TS surface promote pore formation, thus resulting in the highest porosity among the specimens. This reduces the positive effects of TS on the drying shrinkage, chloride penetration resistance, and carbonation resistance compared with using GS. However, a comprehensive evaluation of TS demonstrates its significant potential as a sustainable sand replacement for concrete applications.