Influence of recycled plastic on the thermal transmittance and sustainable assessment of concrete mixes

This study uses recycled plastic (RP) as a fine aggregate in an attempt to minimize the waste on our planet. The results of the study suggest that the use of plastic in the construction sector does not only help minimize the production cost but also helps to increase environmental sustainability. In this study, the performance of a concrete mixture is evaluated based on seven different factors, namely: compressive strength, density, thermal conductivity, R-value, U-value, production cost (material and transportation costs), and eCO2 (embodied carbon dioxide) emission value. In line with the purpose of this study, a cost assessment, environmental assessment, and performance assessment have been carried out. Results indicate that as the plastic ratio increases, the compressive strength of the concrete decreases up to 35.16% in RP mixes. In particular, when 50% RP content is used, the lowest strength is obtained as 24 MPa. On the other hand, 50% RP content decreases the density and thermal conductivity to 2,200 kg/m3 and 0.458 W/mK, respectively. The results also reveal that increasing the RP content in the concrete mix reduces the U-value by 19.88% whereas 50% RP content increases the R-value up to 54.61%. The lower U value of RP indicates the ability of the material to resist heat flow and provides a better insulative value. In this research, cost and environmental assessments were also carried out. Based on cost calculations, RP4 showed the lowest cost because 50% of it is was composed of recycled plastic. Therefore, based on the cost analysis, it is the most beneficial element for use in a concrete mix. On the other hand, the use of recycled plastic leads to an increase in the carbon dioxide emissions while decreasing the amount of plastic waste for sustainability.