Polyethylene terephthalate aggregates in structural lightweight concrete: a meta-analysis and review

There is growing interest in the use of recycled materials in the building sector as a way to reduce waste and improve environmental sustainability. Polyethylene terephthalate (PET) is a thermoplastic polymer that has attracted the attention of researchers due to its application in the building industry. In the recent past, many studies have reported on the application of PET aggregates in structural lightweight concrete. This paper presents a review of the findings of 20 studies conducted between 2010 and 2022 randomly. The preliminary findings highlighted include the method of production of PET aggregates and their physical/thermal properties. The review extended further to focus on the extent of incorporation, physical properties, strength properties, and durability of concrete with PET aggregates. The substitution of PET aggregates up to 20% reflected positively on the compressive strength, while tensile and flexural strength had positive responses up to 10%. Water absorption as a measure of concrete durability increased with the addition of PET aggregates. A meta-analysis of these findings was performed using hypothesis testing (t-test and f-test) to identify significant differences between the experimental outcomes of PET incorporation in concrete. Experimental procedures with greater tolerance for PET inclusion and satisfactory concrete properties were highlighted. The paper recommends the formulation of hybrid mix proportions, developed from experimental designs with noteworthy inclusion of PET aggregates and those that attained high values of desired concrete properties. Furthermore, optimization should be performed to provide robust mix designs for high-strength or lightweight concrete with PET aggregates.