Unleashing high-volume waste plastic recycling in sustainable cement mortar with synergistic matrix enabled by in-situ polymerization

Abstract

The substantial energy consumption and CO2 emissions associated with the production and transportation of concrete and its components have necessitated the search for suitable replacements, particularly waste materials such as plastic, to mitigate their environmental impact. The emergent challenge of employing recycled waste plastics (RWP) in concrete centers around their poor interactions with the cement matrix. Here, a synergistic approach with in-situ polymerization by using sodium acrylate (SA) at various doses (0 %, 0.5 %, 1 %, 2 %) was employed to produce environmentally-friendly mortars. Recycled polypropylene (PP) particles were adopted as the aggregate to replace natural sand in cement mortar. Results indicate decreased water contact angel by 46 % and increased pull-off strength by 25 % for SA-polymerized PP. Moreover, mortars with 2 % SA exhibited a 31 % increase in compressive strength, a 64 % increase in flexural strength, a 76 % reduction in water sorptivity, and a 13.6 % decrease in total porosity. The formation of interconnected polymeric networks in the cement matrix and interfacial transition zone (ITZ) contributes to structural densification, highlighting the superior engineering properties. These findings present a promising pathway towards sustainable and resource-efficient building materials, fostering a circular economy for plastics.