Time-dependent behaviour of hardened cement paste under isotropic loading

International audienceThe experimental results of isotropic compression tests performed at 20°C and 90°C on a class G hardened cement paste hydrated at 90°C (Ghabezloo et al., 2008, Cem. Conc. Res. 38, 1424-1437) have been revisited considering time-dependent response. Within the frame of a viscoplastic model, the non-linear responses of the volumetric strains as observed in drained and undrained tests and of the pore pressure in undrained tests are analysed. The calibration of model parameters based on experimental data allows to study the effect of the test temperature on the viscous response of hardened cement paste showing that the creep is more pronounced for a higher test temperature. The effect of the hydration temperature on the time dependent behaviour is also studied by evaluating the model parameters for a cement paste hydrated at 60°C. The time-dependent deformations are more pronounced for hydration at a higher temperature

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

Des essais de compression isotrope drainés jusqu'à 60 MPa sur des échantillons de ciment montrent un comportement fortement non-linéaire de la pâte de ciment et aussi la présence de déformations différées significatives sous forte contrainte isotrope. Un modèle rhéologique viscoplastique est proposé et étalonné sur les résultats de ces essais. Les paramètres évalués montrent les effets de la température d'hydratation et la température d'essai sur le comportement différé et l'endommagement à court-terme et long-terme de la pâte de ciment durcie

Effect of the curing temperature on the creep of a hardened cement paste

International audienceUniaxial creep tests have been performed at ambient temperature on a saturated hardened class G cement paste hydrated at 60 degrees C and 90 degrees C. The results have shown that creep is enhanced at higher curing temperature. The visco-damage model of Challamel et al. (2005) has been extended and used to analyze the experimental results. The model parameters have been calibrated on the results of the creep tests performed at different stress levels for both curing temperatures. The model correctly reproduces the effect of the curing temperature on time dependent properties of the material. The enhanced creep at higher curing temperature is attributed to the development of more damage in cement paste and to significant weakening of the mechanical properties. (C) 2012 Elsevier Ltd. All rights reserved