High temperature effect on mechanical properties of autoclaved aerated concrete

Abstract

In this paper, an experimental study on mechanical properties at high temperature of a typical autoclaved aerated concrete (AAC) tested in compression is presented (compressive strength = 5 MPa and density = 600 kg/m3 at 20 °C). Parameters such as the compressive strength, strain at the peak stress, and elastic modulus are investigated, along with the stress-strain response in the thermal range 20–700 °C. The behavior of the AAC tested in this research project is different from that of normal concrete, because of a series of chemo-physical processes occurring at high temperature. Between 100 and 600 °C, the compressive strength increases and then starts decreasing (+51% at 600 °C and +10% at 700 °C compared to ambient conditions). The strain at the peak stress increases as well with the temperature similar to – but more than in – normal concrete. The stress-strain curves and the failure modes show that AAC’s behavior is brittle at any temperature and that the damage inside the material increases with the temperature in such a way that the existing models for normal concrete exposed to high temperatures cannot be used in the case of AACs. Hence, a new polynomial model is proposed to properly describe the constitutive behavior of AACs at high temperature.