Impact of granular material size and curing conditions on the properties of a building material with melted plastic waste as the only binder

In recent years, environmental protection has drawn considerable attention across the world and new initiatives are being adopted to develop eco-friendly or cementless concrete or building material as an alternative to Portland cement based concrete or construction materials. Among these works, there are the use of plastic wastes as a binder or substitute/replacement for granular materials in the concrete. This paper aims to investigate the effect of curing conditions and granular material size on the physical and mechanical properties of a cemented construction material, PlasticWasteCrete (PWC), using melted plastic wastes (HDPE and LDPE) as the only binder. Two curing conditions, namely, air dry at ambient temperature and thermal shock in water were used for this research. Moreover, the dimension the size of the granular materials (sand and gravel) was varied in order to test its impact on the physical and mechanical properties of the corresponding PWC sample formulations with given plastic content and HDPE/LDPE (H/L) ratio. Independent of the plastic content and H/L ratio, the reinforcement of granular material skeleton by adding coarser grains was found to increase both compressive and splitting tensile strengths of the corresponding PWC samples. However, subjecting the hot PWC to thermal shock in water shortly after casting was found to decrease its strengths (UCS and tensile) in comparison to the PWC samples cured at ambient temperature. These changes in the material strength, which are linked to the porosity and pores interconnectivity of the tested samples, are in good correlation with the permeability/absorption results. The samples with lower strength were observed to have higher rate of absorption. Linear relationship with high correlation coefficient was established between the UCS and splitting tensile strength of the PWC subjected to thermal shock in water.