Behaviour and residual strength prediction of recycled aggregates concrete exposed to elevated temperatures

Natural aggregates replaced partially or fully with recycled concrete aggregates (RCA) in preparing concrete has emerged as a sustainable construction technique and investigating the properties of such concrete has already been the focus of number of published studies. However, limited data are available for the case of recycled aggregate concrete (RAC) when it is exposed to extreme conditions like elevated temperatures resulting from accidental fires. In this study emphasis was, therefore, made to investigate residual properties of RAC in terms of compressive and tensile strengths, modulus of elasticity, Poisson’s ratio, and concrete mass loss of RAC subjected to elevated temperatures by conducting a detailed experimental investigation. For this purpose, concrete cylindrical specimens were cast having 0%, 30%, 50%, 70% and 100% RCA. These cylinders were then exposed to elevated temperatures ranging from 250 to 900 °C. Based on the experimental results, Elastic modulus and Poisson’s ratio were found to be significantly influenced for the specimens having percentages of recycled aggregates above 30% and when subjected to temperature elevation of above 500 °C. Overall, behaviour of RAC was more or less similar to natural aggregate concrete with a higher degree of deterioration. Furthermore, a residual strength factor (RSF) was also proposed to predict the residual strengths of RAC exposed to elevated temperatures which can be used effectively to estimate residual strengths of NAC and RAC when exposed to elevated temperatures.