Performance of sustainable concrete incorporating recycled polyethylene terephthalate (pet) granules

Performance of sustainable concrete incorporating recycled polyethylene terephthalate (pet) granules

The use of wastes as a supplementary material in concrete manufacturing is of great interest due to the potential cost savings, preservation of natural resources and reduction in environmental pollution. This study focused on the performance of sustainable concrete containing recycled polyethylene terephthalate (PET) waste in the form of granules. The mix was designed for normal strength concrete using PET granules as a partial replacement for fine aggregates (0%, 10%, 30%, and 50% by volume). Firstly, the mechanical properties were evaluated by conducting compressive strength, tensile strength, elastic modulus, flexural strength and crack mouth opening displacement tests along with microscopic analysis. The test results showed that PET granules improve the mechanical properties and ductility of the concrete, although the improvement was more noticeable for 10% PET concrete. The Australian and American design guidelines accurately predicted the experimental results for mechanical properties of PET concrete. Secondly, the bond behaviour between steel reinforcement and concrete mixes, as well as flexural and cracking performance of reinforced concrete (RC) beams were examined together with porosity of the concrete mixes. The findings revealed that the inclusion of 10% PET granules positively impacted the bond strength, flexural strength and cracking behaviour, and porosity of concrete. However, the performance was deteriorated with increasing PET granule percentage. The cracking and flexural moments of PETRC beams were conservatively predicted by the American and Australian standards. The flexural behaviour of RC beams was simulated using finite element method, and the results agreed well with experimental findings. Thirdly, the long-term durability properties were investigated by performing alkali-silica reactivity (ASR), creep strain, shrinkage strain, rapid chloride penetration (RCP), water absorption and apparent volume of permeability (AVPV) tests. The results showed that ASR expansion of concrete prisms and mortar bars decreased with increasing PET aggregate percentage. Including 10% PET aggregates improved chloride resistance and creep strain while having almost no effect on shrinkage, water absorption and AVPA of concrete. A shrinkage model was proposed for concrete containing PET aggregate and the results corresponded well with the experimental results. An in-depth understanding of the behaviour of sustainable concrete incorporating recycled PET granule aggregate was the significant outcome of this study.

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