Comportement différé d'une pâte de ciment durcie sous chargement isotrope

Drained isotropic compression tests on hardened cement paste samples show a highly nonlinear behaviour and also the presence of time dependent deformations under high isotropic stress, up to 60MPa. The studied cement paste has been prepared with a class G oil cement and a water to cement ratio w/c=0.44. Effects of hydration temperature and test temperature have been investigated by preparing different samples hydrated at 60°C and 90°C under saturated condition and by performing drained isotropic compression tests at 20°C, 60°C and 90°C. The test results show a degradation of the elastic properties with an increase of the hydration temperature and of the test temperature. The results reflect also that there exists a stress threshold beyond which the volumetric strains develop more rapidly. A viscoplastic model is proposed and calibrated on the results of the isotropic compression tests. The effects of the hydration and test temperatures on the parameters of the model are discussed. Mots clefs : pâte de ciment, hydratation, comportement differe, modele viscoplastique