Experimental investigation of the effect of temperature on the first desorption isotherm of concrete

In the framework of the radioactive waste management in France, interim storage concrete structures should be submitted to temperatures up to 80 °C and subsequent desiccation. The impact of temperature on the sorption properties of concretes has been poorly studied and results are scarce. An experimental campaign was thus carried out to characterize the first desorption isotherms of a modern concrete at 30 °C and 80 °C. The results show a significant influence of the temperature increase that will have to be accounted for the durability assessment of the long-term interim storage concrete structures. Investigating the causes of these modifications, it appeared that desorption induced by temperature might be the principal mechanism rather than microstructure alteration and water properties evolution.