Correlation between transient creep of concrete and its dehydration
Résumé
The current paper deals with the transient thermal creep of concrete subjected to high temperatures. This phenomenon is related to the dehydration process of hydrated cement paste under temperatures exceeding 105 degrees C. The present paper reports the results of transient creep tests of high-performance concrete (HPC) under constant loads and increasing temperatures up to 400 degrees C. The heating is applied with a rate of 1.5 degrees C/min until successive temperature plateaus are reached ( 150 degrees C, 200 degrees C, 300 degrees C and 400 degrees C). Moreover, the mass loss of the cement paste, corresponding to the HPC, is investigated through a thermo-gravimetric analysis (TGA). This approach makes it possible to identify the dehydration of the material either at equilibrium or at the same heating conditions as in the transient creep tests. It is therefore shown that transient creep and dehydration occur simultaneously and have comparable kinetics. Further, the dehydration is considered as the driving process of the transient creep strain.