From waste to strength: Experimental design and optimization of mechanical properties of concrete using reused PVC-U drainage pipes

Morocco faces a severe plastic waste management challenge due to its high consumption and limited recycling rate. This situation has brought about unfavorable consequences in several fields. To address this issue, the investigation is concentrated on using reused PVC-U (unplasticized polyvinyl chloride) drainage pipes as a substitute to sand in concrete. Seven concrete mixtures containing PVC-U waste were prepared as a partial replacement for sand with substitution levels (0%, 5%, 10%, 15%, 20%, 30%, and 50%). Concrete was poured to investigate the fresh and hardened behavior of concrete containing plastic waste specifically focusing on its workability, fresh and dry density, compressive strength, splitting tensile strength, modulus of elasticity, ductility, and ultrasonic pulse velocity. The results indicate that slump, fresh and dry density were reduced, while mechanical properties were improved by using optimal percentages. Furthermore, multi-objective optimization was used to determine the best ratio for balancing concrete properties.