Tensile and flexural behaviour of recycled polyethylene terephthalate (PET) fibre reinforced geopolymer composites

This paper presents the effect of recycled Polyethylene terephthalate (PET) fibre as reinforcing fibre for geopolymer composite. Tensile and flexural behaviour of PET fibre reinforced ambient cure geopolymer (ACG) composite is studied and compared with those of counterpart cement and cement-fly ash (CFA) composites reinforced by the same fibre. The results are also compared with commercially used polypropylene (PP) fibre reinforced composites. Results show that the compressive strength of PET fibre reinforced ACG composite is higher than its counterpart cement and CFA composites. The compressive strength of all three composites reinforced by PP fibre is slightly higher than that of PET fibre composites. The increase in fibre volume fraction from 1% to 1.5% shows reduction in compressive strength in all three composites reinforced by both fibres. The PET fibre reinforced ACG composite exhibits strain hardening and deflection hardening behaviour in uni-axial tension and three-point bending, respectively. However, in PET fibre reinforced cement and CFA composites no such behaviour is observed. Microstructure observation in terms of scanning electron microscope (SEM) images show no significant damage of PET fibres in geopolymer composite. However, in cement and CFA composites adherence of matrix and damage of PET fibres surface in terms of scratches are observed in SEM observation indicating higher interfacial bond of PET fibre with cement and CFA matrix than with geopolymer matrix. (C) 2020 Elsevier Ltd. All rights reserved.