Assessment of mechanical and durability properties of FA-GGBS based lightweight geopolymer concrete

The relentless consumption of natural aggregates and cement in concrete due to rapid construction has resulted in the exhaustion of natural resources; consequently, it's vital to create environment friendly building materials and implement sustainable construction methods. The development of geopolymer concrete (GPC) is a step towards the utilization of by-products. This study aims to prepare and assess the durability and mechanical characteristics of fly ash (FA) and ground-granulated blast furnace slag (GGBS)-based lightweight geopolymer concrete (LWGC). Utilizing sintered fly ash aggregate (SFA) in GPC is one such approach that can lower the usage of regular cement and natural aggregates. In the present investigation a total of six GPC mixes were prepared with varying alkaline activator to binder (AA/B) ratios of 0.3–0.8. The results shows that the AA/B ratio and the mechanical characteristics of LWGC samples are inversely related. The mechanical properties exhibits maximum strength at the lowest AA/B ratio. The LWGC achieved the highest compressive strength (CS) of 48.9 MPa, modulus of elasticity (EM) of 27.3 GPa, split tensile strength (STS) of 3.9 MPa, and direct shear strength of 5.4 MPa after 28 days of ambient curing. The oven dry density (OD) ranged from 1722–1805 kg/m3, satisfying the various codal provisions to be considered a lightweight concrete (LWC). The durability study indicates that for structural applications, the performance is satisfactory, especially in acidic conditions. SEM and EDS analyses also infer strong mechanical and durability characteristics. The obtained results suggests that LWGC is a possible material for structural concrete applications.