Effects of Polypropylene Waste and Functionalized Polypropylene Waste on the Properties of Sand Concrete and Lightweight Concrete Made with Sintered Fly Ash

In response to the growing environmental concerns of plastic waste disposal, waste polypropylene (wPP) holds potential as an alternative to sand and lightweight aggregate (LWA) in the dematerialization of concrete mixes. Recent studies have explored the incorporation of various forms of plastic waste into concrete, but often disregard the potential detrimental hydrophobic surface interactions from the plastic in mixes. This present study developed and implemented surface functionalised waste polypropylene (f-wPP) containing a hydrophilic surface to mitigate the detrimental interactions and to determine consequential improvements on compressive strength, flexural strength, flow, and density. The two control samples: mixture of sand and cement, and a mixture with sintered fly ash (SFA) and cement, are both compared to samples with 20% volume of fine aggregate (sand or SFA) replaced by wPP and f-wPP. The findings indicate that the incorporation of wPP resulted in a notable reduction in flexural strength, compressive strength, and flow, compared to the control mixes. However, the concrete mix incorporating f-wPP showed promising results, with improvements in both compressive, flexural strength and workability compared to the mix with untreated wPP. These results suggest that f-wPP could serve as a viable alternative to conventional sand and LWA in concrete mixes, offering environmental benefits and comparable performance.