Mechanical properties of a mortar with melted plastic waste as the only binder: Influence of material composition and curing regime, and application in Bamako

Abstract In recent years, serious environmental problems induced by plastic wastes have drawn considerable attention across the world and new initiatives have been adopted to recycle plastic wastes into construction materials. One of the promising initiatives is the use of plastic waste as the only binding phase to make concrete/mortar-like construction materials. However, how key engineering properties of concrete/mortar-like materials with melted plastic as the only binder change with material composition and curing conditions are not well known. This paper aims to investigate the effect of curing conditions and granular material size on the mechanical properties (compressive and splitting tensile strengths) of a mortar with melted plastic waste (high density polyethylene (HDPE) and low density polyethylene (LDPE)) as the only binder (MPB: mortar with melted plastic waste binder). Moreover, it presents a study conducted in the city of Bamako (Mali) to evaluate the use of MPB to make interlocking paving blocks for use on non-traffic areas in residential or municipal construction projects. Two curing conditions, namely, air dry at ambient temperature and water curing were used for this research. Moreover, the size of the granular materials (sand and gravel) was varied in order to assess its impact on the properties of the corresponding MPB sample formulations with given plastic content and HDPE/LDPE (H/L) ratio. Granular material size and curing conditions were found to have significant impact on the mechanical strengths of the MPB materials. Regardless of age and H/L ratio, the MPB samples cured in water showed lower strength (compressive and tensile) than the specimens cured at ambient temperature under controlled laboratory conditions, while adding coarse granular materials helped to improve these strength properties. Furthermore, the mechanical performance of the proposed MPB-interlocking paver is superior to that of the interlocking Portland cement-based pavers that are commercially available on the Bamako's market. Moreover, the cost of the Portland cement-less MPB-paver will be substantially lower than that of the Bamako's commercial Portland cement-paver. The obtained results place this MPB material as a promising candidate for making interlocking pavers or other products, while reducing the amount of plastic waste to be managed and the cost of interlocking pavers.