Quasi-static and Dynamic Mechanical Properties of Engineered Geopolymer Composites with Hybrid PVA and Recycled Steel Fibres

Recycled tyre steel (RTS) fibre is favoured as a replacement for industrial steel fibre to reduce the environmental impact and material cost of fibre reinforced cementitious composites as well as a potential substitute for the commonly used polyvinyl alcohol (PVA) fibre to develop sustainable engineered geopolymer composites (EGC). This paper systematically examines the effect of hybrid PVA and RTS fibre dosage on the engineering properties of fly ash-slag based EGC, with special focus on uniaxial tensile behaviour and dynamic compressive and splitting tensile behaviour. Results indicate that combining RTS fibres with PVA fibres can effectively improve the drying shrinkage resistance of EGC. All studied EGC mixes exhibit expected strain-hardening and multiple cracking behaviour under uniaxial tension and about 5% enhancement in tensile strength is captured for EGC when 0.25% PVA fibre is replaced with RTS fibre. The incorporation of RTS fibres can improve the quasi-static compressive strength of EGC up to 31%, as compared to EGC with 2.0% PVA fibre. Replacing 0.25 to 0.5% PVA fibre with RTS fibre is beneficial to the dynamic mechanical properties of EGC, where up to 20% improvement in dynamic splitting tensile strength is found for EGC.