Potential utilization of waste plastic in sustainable geopolymer concrete production: A review

Plastic production has increased manifold over the last decade, with worldwide production reaching 400 million tonnes in 2021, and the trend is estimated to have a sharp rise in the future. Apart from being non-biodegradable, plastics are essentially durable, which makes waste plastic disposal extremely difficult and poses a threat to solid waste management. Disposal methods, including incinerating, landfilling, disposal into water bodies, etc., are having hazardous environmental impacts. Hence, plastic recycling is essential for ensuring sustainability. The construction industry is a major contributor to global warming primarily due to the Portland cement production emitting 6% of global CO₂ production. Growing awareness has emphasized partial replacement of Portland cement with other binders, such as metakaolin, fly ash, slag, etc., to be used in conventional composites or complete replacement to yield geopolymer composites. Waste plastics can be used in geopolymer concrete (GPC) as a partial or complete replacement of natural aggregates or added as fibers. Based on the above background, various researchers have incorporated plastics in GPC in the form of aggregate replacement or fiber addition, justifying sustainability and enhancing GPC characteristics. Plastic supplementation in GPC is a relatively new research domain. An attempt has been made through the current review work to develop a comprehensive database established on various concrete characteristics through the globally available research performances involving various forms of plastic incorporation in GPC yielding plastic-supplemented GPC (PSGPC). A detailed plastic classification and varying forms are poised, with identified plastics elicited from its global acceptance so far in PSGPC production. Through various PSGPC characteristics like fresh, physical, mechanical, durability, and microstructural analysis with different plastic types and forms, the optimal waste plastic disposable range is entrenched justifying eco-friendly and sustainable concrete yield.