Modeling of early-age creep of shotcrete. I: Model and model parameters

In this paper, creep and viscous flow are revisited from the standpoint of constitutive modeling of thermo-chemo-mechanical couplings in early-age con crete. Within the framework of closed reactive porous media, creep is model ed by means of two mechanisms: a stress-induced water movement within the m acropores and a relaxation mechanism in the micropores of cement gel, both of which lead to aging effects on creep and viscous flow of concrete. Regar ding the first creep mechanism, aging results from chemomechanical coupling s. Concerning the second mechanism, long-term aging is attributed to the re laxation of microprestresses in the micropores. Following the formulation o f the model, it is shown how the material parameters can be identified from creep tests performed at different ages of loading. Finally, the model is applied to shotcrete, for which proper experimental data are missing.