Computational modelling of the basic creep of concrete: An image-based meso-scale approach

Abstract

A 2D meso-scale numerical model is presented to investigate the basic creep of concrete, which is also applicable to various cementitious materials. The model runs a direct image-based analysis in which the internal structure of the material is obtained from X-ray micro-CT scanning. An automatic and robust quadtree decomposition algorithm is employed to convert digital images into meshes, which are then solved using the scaled boundary finite element method based on a continuum approach. Concrete and mortar are treated as a three-phase composite, consisting of viscoelastic binder, elastic aggregates and voids. The debonding of the interfacial transition zone between the aggregates and the binder is modelled using zero-thickness interface elements with traction separation laws. The basic creep model is based on a rate-type rheological model corresponding to a Kelvin chain and accounts for ageing. Numerical examples are carried out on both concrete and mortar images. The numerical study highlights some of the phenomena associated with the creep response and explores the capabilities of the proposed model.