Effect of recycled tyre polymer fibre on engineering properties of sustainable strain hardening geopolymer composites

Abstract

Strain hardening geopolymer composite (SHGC) processing superior tensile ductility and multiple cracking is a promising alternative to traditional ductile cementitious composites whereas the extremely high cost of polyvinyl alcohol (PVA) fibres limits its large-scale application. This paper presents a feasibility study of replacing PVA fibres with recycled tyre polymer (RTP) fibres to reduce the material cost of fly ash-slag based SHGC and ease the pressure on environmental impact induced by the vast amount of waste tyres, focusing on the influences of PVA fibre content (1.0–2.0% by volume) and RTP fibre replacement dosage (0.25–1.0% by volume) on the engineering properties especially uniaxial tensile behaviour, microstructure, material cost and environmental impact. Results indicate that the incorporation of RTP fibres into SHGC can lessen the loss in flowability and compressive strength due to the addition of PVA fibres. The drying shrinkage of SHGC containing RTP fibres is effectively reduced by about 35.69% and 17.33% as compared with the plain matrix and SHGC containing 2.0% PVA fibre, respectively. Although the presence of more RTP fibres diminishes the uniaxial tensile behaviour of SHGC, the cost and embodied energy of SHGC utilising RTP fibres are reduced by up to 34.52% and 16.23%, respectively. SHGC with 1.75% PVA fibre and 0.25% RTP fibre can be considered as the optimal mixture as it provides adequate engineering properties including a tensile strain capacity of around 2.5%, lower material cost and lower environmental impact compared to the typical SHGC with 2.0% PVA fibre.