Synergistic Effects of Fly Ash Geopolymer and Superplasticizer on PET-Modified Concrete

Abstract

The growing environmental issues of cement production, the exhaustion of natural aggregates, and the dumping of plastic waste have led to the necessity of providing the construction industry with sustainable alternatives. Despite the previous studies that have investigated recycled PET plastic, fly ash geopolymers, and superplasticizers when examined individually, very few studies have been conducted where these are studied in combination and in their synergistic effects in concrete systems. This paper thus examined the synergistic nature of fly ash geopolymer and superplasticizer on concrete that had 5% PET plastic as a partial substitution of fine aggregate. The fresh, mechanical, and durability properties of concrete were investigated using experimental studies. Tests of workability were conducted using slump tests, whilst compressive strength test, split tensile strength test, and flexural strength test were conducted at 7, 14, and 28 days of curing. The performance on durability was evaluated by carrying out acid resistance tests using solutions of hydrochloric acid and sulphuric acid. The findings indicated that the incorporation of PET decreased workability and mechanical strength relative to traditional concrete. Nevertheless, the performance of PET-modified concrete was greatly enhanced by the incorporation of superplasticizer and fly ash geopolymer. These optimum workability and strength performance were realized under 3% - 4% of superplasticizer and 3% - 4% of fly ash content. The compressive, tensile, and flexural strength was enhanced by the combined effect of fly ash and superplasticizer, which improves the dispersion of particles, densification of the matrix, and the reaction of pozzolana. There was also an improvement in the durability performance, since there was lower porosity and greater resistance to acid attack. The paper concludes that the negative impact of PET plastic in the concrete can be effectively utilised through the synergistic incorporation of fly ash geopolymer and superplasticizer in the concrete. The results justify the use of recycled PET and fly ash within the construction of environmentally friendly concrete. Long-term durability, microstructural behavior, and large-scale field applications should be investigated in future studies to enable policy formulation and industrial use of sustainable construction materials.