Influence of plastic waste addition on mechanical properties of cement mortars: An experimental study

Abstract

With the increasing need for sustainable construction materials and to cope with plastic waste management, a lot of research has been undertaken on the recycling of plastics in cementitious composites. An experimental investigation was performed in the current study to study the effect of adding ground polyvinyl chloride (PVC) waste particles on physical, mechanical and thermal properties of cement mortars. Fifteen series of mortar mixtures were made with four plastic contents (5%, 10%, 15% and 20% by cement weight) and three water-to-cement (w/c) ratios (0,35, 0,40 and 0.45). Workability, density, thermal conductivity and flexural and compressive strength were investigated by comprehensive tests in compliance with the applicable ASTM standards. The results obtained showed that plastic admixture induced a significant reduction in mortar density (up to 4.5%) and thermal conductivity (11%), representing its applicability as an artificial lightweight material. It was shown that workability was more affected by plastic dosage amount and w/c ratio according to the flow table test results, whereas moderate amounts of plasticizer enhanced workability. It was also found that the mechanical performance followed nonlinear behavior, where the flexural strength increased by approximately 43% and compressive strength up to 59% with a 5% plastic content achieved; thereafter, both performances decreased at higher concentrations due to the lack of strong interfacial bonding with particles and higher porosity. The findings demonstrate that the controlled incorporation of plastic waste at low dosages is mechanically feasible and effective, identifying 5-10% addition as the optimal range for improving mortar performance without compromising strength.