Investigation on recycled aggregate concretes exposed to high temperature by biaxial compressive tests

•RACs were investigated experimentally under biaxial compressive actions after high temperatures.•Evolutions of biaxial compressive strength, deformation and the stress-strain curve with the variation of stress ratios, replacement rates and high temperatures were concluded.•Biaxial compression strength experiences a parabolic-curve variation with the stress ratio, and the correlated strain increases with the temperature elevation at the same replacement rate and stress ratio.•Improved strength failure criterion of RACs has been established based on the Kufer-Gerstle criterion and data regression analysis. Recycled aggregate concretes (RACs) made of building wastes can achieve good environmental and economic benefits. Since fire is one of the most common disaster in modern high-rise buildings, the strength, deformation and bearing capacity of recycled concrete structures under high temperatures should be carefully studied in design. The mechanical performances of RACs exposed to high temperatures under biaxial compressive actions have been studied in this research. The RAC specimens with three replacement rates (0%, 50%, 100%) exposed to high temperatures (200 °C, 400 °C) have been tested. The influences of stress ratios, replacement rates and high temperatures have been investigated intensively. Failure criterions with improved accuracy have been proposed to describe the strength failure characteristics of the RACs. The results indicate that biaxial compressive strength and peak strain after high temperature show an increase compared with that under normal temperature, and the biaxial compressive strength and peak strain have opposite trend with the variation of replacement rate and temperature. The study can provide a scientific instruction for the design of RACs exposed to high temperature.