Effect of chemical exposure on mechanical properties and microstructure of lightweight polymer composites containing solid waste fillers

•Exposure to three aggressive chemicals of lightweight polymer composites is studied.•Compressive strength of lightweight polymer composites are increased after exposure to chemical solutions.•Mixed results are observed in the case of flexural strength. This paper presents the effect of sulphuric acid (H2SO4), magnesium sulphate (MgSO4) and sodium chloride (NaCl) solutions on mechanical properties and microstructure of lightweight polymer composites containing recycled Polyethylene terephthalate (PET) flakes, recycled tyre crumb rubber (CR) and fly ash (FA) as fillers. The lightweight polymer composites are exposed to 1 mol H2SO4, 1 mol MgSO4 and 0.5 mol NaCl solutions for one to six months. Compressive strength, density, flexural strength and microstructural analysis are conducted to evaluate the residual behaviour of the composites after their respective exposure duration. Based on test results, it is found that most of the developed lightweight polymer composites exhibited better residual compressive strength after exposure to above chemical solutions. Mixed results are obtained in the case of residual flexural strength. No significant change in density of the polymer composite is observed in all composites at different exposure periods and solutions. The microstructural analysis revealed no deterioration of the composite nor any additional reaction products formed in the composites after exposing to those aggressive solutions.