Improving thermal and mechanical properties of concrete by using ceramic electrical insulator waste as aggregates

• Investigating the thermal characteristics of concrete including crushed insulator aggregates. • Using insulator waste as aggregates to produce environmentally friendly concrete. • The thermal conductivity of concrete was predicted by regression analysis. Improving the energy efficiency of the buildings over their lifetime and reducing the environmental impact of buildings design are considered the major challenges in their sustainable design. In recent years, the use of recycled aggregates and wastes have played a major role in reducing the environmental impact of the building sector following the advancement of concrete technology. However, the thermal performance of concrete including recycled aggregates and wastes exposed to heat and sunlight has not been simulated so far. This study focused on designing, simulating, and evaluating the thermal and mechanical performance of concrete made with ceramic electrical insulator waste. For this purpose, the crushed ceramic electrical insulator wastes were replaced independently for each of the natural sand and gravel at 25, 50, 75, and 100%. Moreover, the combined replacement of coarse and fine insulator waste aggregates at 50 and 100% levels was examined. The compressive strength, water absorption percentage, thermal conductivity, and thermal performance tests were performed. Based on the results, the compressive strength increased and the water absorption decreased in all levels of replacing natural aggregate with ceramic insulator wastes, compared to control specimens. In addition, the thermal conductivity was reduced by nearly 48% in the case of complete replacement of aggregates with crushed ceramic insulator waste, while the reduction was about 21 and 37%, respectively, in the case of replacement of natural coarse and fine aggregate separately with ceramic wastes. The results showed that concrete mixtures containing ceramic electrical insulator waste reduced the slope of temperature changes under heat radiation, and preserved the environment as a step towards sustainable development. Finally, the thermal conductivity of concrete made with crushed ceramic electrical insulator waste was predicted by regression analysis in order to develop guidelines for sustainable construction.