Coupled Damage and Multiscale Creep Model Applied to Cementitious Materials

In this study, we present a coupled creep and damage model for describing the behavior of cementitious materials. The creep model is based on a multiscale approach where the material is represented as a composite made of a linear viscoelastic matrix with distributed spherical elastic inclusions and pores. The Mori-Tanaka scheme is then applied in the Laplace-Carson space to this composite material. Exact analytical expressions of the moduli in the time space are derived in simpler cases when a limited number of Maxwell elements are involved to describe the matrix behavior. The model is compared to finite element simulations results carried out on 3D mesostructures. Several configurations of mesostructures with different volume fractions of spherical inclusions ranging from 25 to 40% and boundary conditions are analyzed. The creep model is further coupled to the isotropic damage model due to (Mazars 1986) at the macroscale, based on the concept of pseudo-strains which allows reformulating the initial viscoelastic problem as an equivalent elastic one. The evolutions of the damage variable are governed by an equivalent pseudo-strain calculated from the pseudo-strains tensor. The model is then applied to the simulation of concrete basic creep tests at different temperatures.