A review of utilization of waste polyurethane foam as lightweight aggregate in concrete.

Engineered concrete mixes using industrial waste as a construction material are an enormous step towards sustainable development and financial benefits. The refrigeration, automobile, and construction industries mainly generate polyurethane foam waste material. Most of the polyurethane foam wastes are dumped in landfills or incineration, which creates environmental effects. Polyurethane foam waste is challenging to recycle because of its bulky nature, limited recycling methods, high transportation costs, complex chemical composition, and inadequate collection and processing infrastructure. Utilizing waste polyurethane foam as lightweight aggregate in concrete serves a dual purpose: reducing natural aggregate extraction and reducing polyurethane foam waste going to landfills. This article reviewed waste disposal rigid polyurethane foam as a lightweight aggregate in concrete mixtures. Initially, it discusses the statistical data analysis, physical and microstructural properties of waste flexible and rigid polyurethane foam. After that, performance evaluations focused on fresh properties by slump tests, hardened properties by compressive strength and density, and microstructure analysis by scanning electron microscopy are presented. The study concludes that incorporating waste polyurethane foam increases workability, improves bonding between polyurethane foam aggregate and the cementitious matrix, and reduces concrete density and compressive strength for lightweight concrete structures. This paper discusses the benefits of utilizing solid waste rigid polyurethane foam in concrete compared to conventional concrete. This study also identified the research gaps in the current state of knowledge and provided few recommendations for future research work.