Damage and failure analysis of concrete using synthetic 3D meso-structures

Concrete is one of the key materials used in the construction of nuclear power plants, with both structural and shielding functions. Understanding the aging of concrete in service is essential prerequisite for advanced plant life assessment. Aging is associated with changes in the complex heterogeneous structure of concrete, which could be chemically and/or mechanically driven. First steps towards modelling and predicting aging can be made by appropriate representations of concrete at its meso-structural length scale, where it is a three-phase composite, containing mortar, coarse aggregates and voids. This work presents generation and packing algorithms for modelling three-dimensional heterogeneous concrete specimens with randomly distributed spherical, ellipsoidal and polyhedral aggregates and voids, with prescribed size distributions, shape and volume fraction. Models are meshed automatically and include cohesive elements at all interfaces between continuum elements. The cohesive elements represent potential crack paths and their traction-separation laws are different within the mortar, within the aggregates and at the interface between these phases. Mesoscale crack initiation, propagation and coalescence are simulated naturally with the cohesive elements. The models are solved by FEM, and statistically analysed to evaluate the effects of mesostructual parameters on the mechanical behaviour. The proposed methodology provides an effective and efficient tool for damage and failure analysis of concrete, and a comprehensive study was conducted for 3D heterogeous concretes in this paper.