Mesoscale models for concrete: Homogenisation and damage behaviour

In this paper three-dimensional geometrical models for concrete are generated taking the random structure of aggregates at the mesoscopic level into consideration. The generation process is based upon Monte Carlo's simulation method wherein the aggregate particles are generated from a certain aggregate size distribution and then placed into the concrete specimen in such a way that there is no intersection between the particles. For high volume fractions of aggregates, new algorithms for generating realistic concrete models are proposed. The generated geometrical models are then meshed using the aligned approach in which the finite element boundaries are coincident with materials interfaces and therefore there are no material discontinuities within the elements. The finite element method (FEM) is used in the direct computation of the effective properties of concrete. The results obtained from the numerical simulations and the subsequent homogenisation are then compared with experimental data. Furthermore numerical simulations of the damage and fracture process of concrete are performed using an isotropic damage model to model the progressive degradation of concrete. Finally, a concrete block is investigated where numerical and experimental results are discussed.