Static and dynamic properties of novel ambient-cured lightweight geopolymer composites with fibre reinforced epoxy coated EPS aggregates

Geopolymer is an alternative binder to ordinary Portland cement (OPC) and expanded polystyrene (EPS) has been used as lightweight aggregates (LWA) to manufacture lightweight geopolymer composites (LWGC). Nevertheless, incorporating EPS beads in LWGC resulted in a significant decrease in mechanical properties as reported in a previous study. To achieve LWGC with a higher strength-to-weight ratio, a new commercially available coated expanded polystyrene (CEPS) with fibre reinforced epoxy was used as LWA for mixing LWGC in this study. Quasi-static and dynamic tests of the developed LWGC were conducted by using the universal test machine and Ø100-mm split Hopkinson pressure bar (SHPB) system, respectively. The physical properties of LWGC, such as density, workability and microstructure, were reported first, followed by the quasi-static mechanical properties including compressive and splitting tensile strength, modulus of elasticity and Poisson's ratio. Then the failure processes and failure modes observed in dynamic compressive and splitting tensile tests were reported and discussed. The strain rate effects on the dynamic properties, including the compressive and splitting tensile strengths, compressive critical strain and modulus of elasticity of LWGC with various CEPS contents, were revealed. The energy absorption capacities of the tested specimens were also examined. Furthermore, empirical formulae were proposed to predict the dynamic increase factors of both the compressive and splitting tensile strengths as well as energy absorption capacities of LWGC.