Recycling of plastic box waste in the concrete mixture as a percentage of fine aggregate

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This study was conducted to assess the effect of plastic box waste particles (PBWPs) on the mechanical characteristics of a concrete mixture if plastic box particles (PBPs) are used as a partial substitute for sand in the mixture. Another purpose was to verify the effect of the waste on the flexural behavior of reinforced concrete beams (RCBs). In this research, four normal concrete mixtures with a water/cement ratio of 0.41 were examined. Three concrete mixtures contained recycled plastic box waste particles by varying the percentage of usage (2.5%, 5%, and 10%) and one mixture without PBPs as reference mixture (RNC) for comparison. To investigate the accuracy impact of the waste on strength and serviceability, three RCBs were tested with dimensions of 150 × 200 × 1400 mm, containing different proportions of the waste within the concrete mixture. Several tests were performed to detect the difference between the mechanical properties of a mixture containing plastic waste and the reference mixture. Cracking investigation, load- deflection behavior, ductility indices, initial stiffness, and secant stiffness were the RCB test variables. The concrete mixture with PBWPs considerably enhanced concrete properties. Results indicated that depending on the quantity of plastic particles replaced by fine aggregate, plastic may have an effect on strength. However, the test results demonstrated that the partial replacement of 5%PBWPs by weight in the mixture increased the compressive strength approximately 30.2%. Incorporating PBWPs into the concrete mixture did not significantly change the failure mode of RCBs compared with that of NC beams. However, the first crack load showed improved results in the hybrid beam (beam with two mixtures of different percentages of PBWPs). The reinforced concrete mixture, which contained 5% plastic particles, exhibited a slight increase during the ultimate failure load with an increment of 1.82%. Moreover, the results of the concrete beam test showed a prominent improvement in ductility, particularly in the hybrid beam; a small increase in the initial stiffness; and a slight decrease in the secant stiffness.