Numerical modelling of interfacial transition zone influence on elastic modulus of concrete

Concrete is a highly complex and heterogeneous three-phase composite composed of aggregates, matrix and the interfacial transition zone (ITZ) between them. As the weakest structure of concrete, the ITZ is often ignored due to difficulty in its modelling using the finite-element method. In this paper, concrete models with high-volume fractions of aggregates are established, in which the ITZ structure is considered. The numerical results for compressive elastic modulus are in good agreement with those obtained from experiments. The influence of the volume fraction, the size of aggregate and the thickness and compressive elastic modulus of ITZ on the compressive properties of concrete have been investigated. The numerical analyses show that the increase of the aggregate volume fraction, ITZ compressive elastic modulus, or the decrease of the ITZ thickness can all lead to the increase of the concrete compressive elastic modulus, while the aggregate size only has a mild effect on it.