Life cycle assessment and mechanical properties of high strength steel fiber reinforced concrete containing waste PET bottle

Polyethylene terephthalate (PET) is widely used as a raw material in the manufacture of beverage bottles, packaging industries, and only after one use becomes waste. Since these types of wastes are decomposed in long term and cause environmental hazards, the issue of recycling and their reuse in the concrete industry could be accounted as a solution. This study has a more comprehensive approach toward examining the plain high strength concrete (PHSC) properties containing different percentages of PET particles including 0, 5, 10, and 15% which could be accounted as a partial volumetric replacement for sand. Moreover, the addition of steel fibers (SFs) volumetric percentages of 0, 0.25, 0.5, and 1% are also investigated. Based on an experimental program the PHSC properties such as the ultrasonic pulse velocity (UPV), compressive strength, splitting tensile strength (STS), modulus of elasticity, and impact response are investigated. The scanning electron microscope (SEM) analysis is performed on the specimens to determine the effect of the PET particles and SFs on the microstructure of PHS. A statistical analysis of variance (ANOVA) is also conducted to obtain the optimal values of the independent variables (PET particle content and SFs), and their interaction effect on the dependent variables (experimental parameters). Furthermore, the life cycle assessment (LCA) of concrete mixes in terms of CO2 emissions is made. The results reveal that by replacing PET particles with up to 15%, the tensile strength and modulus of elasticity decreased by approximately 20% compared to PHSC. Moreover, increasing SFs to 1%, the STS and elastic modulus increased by 77.9% and 18.1%, respectively, however, the impact resistance compared to PHSC increased 43.6 times. In addition, applying concrete containing PET particles is recognized as a more environmentally friendly mixture in terms of reducing CO2 emissions.