Improving the properties of waste plastic lightweight aggregates-based composite mortars in an experimental saline environment

Abstract

The present work aims to highlight the use of polyethylene terephthalate (PET) plastic waste for the conception of a new PET-siliceous sand composite material (WPLA) to be used, after heat treatment, as a light aggregate in various screed mortars. This composite is intended to be employed as a substitute for conventional aggregate at the rates of 0, 25, 50, 75, and 100% by weight. Reinforcement corrosion, caused by the attack of chloride ions, is the main reason for the deterioration of reinforced concrete structures around the world. To determine the effects of waste PET as a lightweight aggregate (WPLA), five WPLAX composite mortar formulations were immersed into a 5% NaCl solution. The mechanical strength, absorption of water by capillary suction, and chlorine ion penetration into mortars were all studied. Additional information on the microstructure of the materials was also collected. The results obtained indicated a decrease in the compressive strength of WPLAX. Moreover, Fick’s second law made it possible to observe a decrease in the penetration of chlorine ions, ranging from 40 to 90% in WPLAX mortars as the replacement ratio increased. Likewise, it was found that the sorptivity coefficients of WPLAX mortars decreased from 43 to 65% as compared to that of reference mortar. These encouraging results open up new prospects for using these composite materials as protective mortars for reinforced concrete structures. At the same time, it is one way of getting rid of these PET plastic wastes which represent a serious pollution form to the environment and a real threat to human health.