An experimental relationship between complete liquid saturation and violent damage in concrete submitted to high temperature

This paper presents a damage mechanism for high performance concrete at high temperature. Crack opening in concrete is related to water thermal dilation: the aim of this work is to propose a low-cost method for verifying, for a given concrete formulation, this damage mechanism and, at least, warn against spalling risk. Concrete specimens (discs of diameter 150 mm and 50 mm thickness) were heated on one face up to a temperature of about 280°C. The temperature and gas pressure fields were constantly measured during the tests. The analysis of the results, together with the curve of the saturating vapour pressure allowed the establishment of a singular and original relationship between the pressure curves, leading to a possible explanation of concrete hygro-thermal damaging and spalling. This experimental correlation underlines the significant role of gas and liquid water inside concrete and allows a deeper understanding of concrete at high temperature