Development of waste-based concrete: influence of glass sand and recycled fine aggregate on concrete properties

Incorporating fly ash (FA) or ground granulated blast furnace slag (GGBS) as substitutes for cement, along with glass sand (GS) or recycled fine aggregate (RFA) as alternatives to natural sand (NS), has been a sustainable approach to minimize the environmental footprint of concrete production and demolition waste. This study presents an experimental investigation into the concrete behavior where NS is entirely replaced with GS and RFA, and cement is fully substituted with FA and GGBS. Eight mixes were produced to evaluate workability, density, compressive, splitting tensile, and flexural strengths, and water absorption. Findings reveal that using 100% GS or 50% RFA as sand replacements reduces the mechanical properties. Concrete containing 100% GS exhibits superior mechanical performance compared to 50% RFA concrete. Additionally, replacing NS with a 50–50% combination of GS and RFA slightly reduces mechanical properties compared to conventional concrete. 100% GS concrete absorbs less water than 50% RFA concrete, and a mix of 50% GS and 50% RFA, with FA and GGBS as complete cement replacements, demonstrates reduced water absorption than conventional concrete. These results highlight the potential of using GS and RFA combined with industrial by-products to produce eco-friendly concrete while ensuring the required mechanical properties and durability.