Numerical analysis of concrete creep on mesoscopic 3D specimens

Abstract : In this paper we investigate analytically and numerically the creep behavior of concrete at mesoscale. The simulations are carried out with the finite element (FE) code (Cast3M) on 3D concrete specimens consisting in about 4600 polyhedral aggregates of various size and shapes randomly distributed in a box. Both matrix and Interfacial Transition Zone (ITZ) are considered as linear viscoelastic materials while the aggregates are elastic. Specific interface finite elements are introduced between the aggregates and the matrix to model the ITZ. The overall and intra-phase response of the numerical specimens when subjected to classical creep loadings is investigated, and then compared to the results of analytical estimations obtained with classical mean-field approximation schemes. These schemes are applied in the Laplace-Carson (LC) space, and the effects of the ITZ are accounted for via appropriate interface models. The results obtained for different ITZ thicknesses are analyzed so as to evaluate their respective influence on mortar and concrete materials