Parametrical study of transient thermal strain of ordinary and high performance concrete

This paper presents the results of an experimental study carried out on several concretes at temperature up to 600 °C. It deals with a high temperature phenomenon of concrete, the transient thermal strain (TTS). From reviews of some experimental and numerical works on TTS, we focused our study on the influence of several parameters: load level, compressive strength, heating scenarios, and nature of the aggregates. We also present results of concrete transient mass loss and strains in the radial direction. The study is completed by an assessment of TTS in uniaxial tension and of pure cement paste in compression. The results of the study allow us to better understand the physical origins of TTS. In particular, the results are consistent with the following explanation: TTS is mainly due to the drying and dehydration of the material up to 400 °C and, at higher temperatures, the increase of TTS can be explained by the thermomechanical damage of concrete.