Thermal resistance behaviour of concrete with recycled plastic waste fine aggregates

In this research work, an attempt is made to use chemically treated and un-treated recycled plastic waste as a partial replacement for fine aggregates in the production of concrete and to evaluate its mechanical properties. The recycled plastic waste (RPW) fine aggregates were treated to improve the adhesion properties of recycled plastic waste with the adjacent cementitious matrix. Both M20 and M40 grades of concrete were considered for the present study. The concrete specimens were cast with 0%, 5%, 10%, 15% and 20% of treated recycled plastic waste (T-RPW) and un-treated recycled plastic waste (UT-RPW) fine aggregates to determine mechanical strength. The thermal behaviour of the concrete specimens with and without recycled plastic waste was also investigated. The specimens were exposed to elevated temperatures in a range 100 °C to 500 °C. Reduction in compressive strength and mass loss were evaluated to investigate the effect of including treated and un-treated RPW fine aggregates on the mechanical performance of concrete at elevated temperatures. The microstructural properties of concrete such as SEM and XRD were also investigated. Test results indicated that the compressive strength of concrete increased with an increase in temperature up to 100 °C beyond which strength decreased. The percentage decrease in compressive strength was 60.0% and 49.2% for 20UT-RPW and 20 T-RPW, respectively, at 500 °C. Greater strength loss was observed at 500 °C due to the decomposition of the RPW fine aggregates and hydration products. Increase in the percentage of RPW fine aggregates and increases in temperature increased the mass loss of the specimens.