Numerical and statistical analysis of elastic modulus of concrete as a three-phase heterogeneous composite

•We analyze the influence of aggregate and ITZ on elastic modulus of concrete.•Ramesh model can theoretically estimate the elastic modulus of concrete.•Soft ITZ can greatly cancel the enhancement of aggregate on elastic modulus.•The RVE size of concrete is determined through numerical-statistical approach.

This paper investigates the elastic modulus of concrete as a three-phase heterogeneous composite. Theoretically, the influence of aggregate and interfacial transition zone (ITZ) can be well characterized by the Ramesh model. Through generation of random aggregate structure, numerical samples of concrete are established and analyzed to calculate elastic modulus. It is shown that soft ITZ can greatly cancel the enhancement of aggregate while stiff ITZ cannot help much to strengthen concrete. The size of representative volume element of concrete is suggested in terms of expected error employing numerical–statistical approach. The required sample size with certain realization number is also calculated.