Interaction between damage and time-dependent deformation of mortar in concrete: 3D FE study at meso-scale

Creep of concrete can be partly attributed to the time-dependent deformation of cement paste and partly to the interaction between load-induced damage of mortar (hardened cement paste) and its non-elastic deformations [1]. The heterogeneity of concrete and related interaction between load-induced damage and non-elastic deformation of mortar can have significant influence on the long-term response of concrete. Some aspects of the problem have been investigated in [1] through 3D finite element (FE) analysis of a concrete cylinder at meso-scale. The concrete is treated as a bi-phase composite material, consisting of coarse aggregate and mortar matrix. The constitutive law for mortar is based on the microplane theory, while the aggregate is assumed to be linear elastic. The results obtained for basic creep and shrinkage, at different levels of applied uniaxial compressive load (both separate and combined action) are reported in [1]. This paper mainly focuses on the effect of cyclic variation of environmental temperature and its interaction with the load-induced damage, basic creep and shrinkage of mortar. It is shown that with higher loading level the increase of time deformation of concrete becomes progressive and the variation of environmental temperature strongly influences time-dependent concrete response.