Modelling the effect of concrete cement composition on its strength and failure behavior

Typical concrete is a mixture of Portland cement, water, and aggregates. While aggregates have a substantial effect on the concrete strength and fracture behavior, the focus of the present study is on the hardened cement paste which can be further divided into the unreacted core, inner and outer products. In high strength concrete, water-to-cement ratio is low, and thus the distance between cement particles is small. Also, the amount of unreacted (high strength) core is higher, and the porosity is low. When water-to-cement ratio is higher, both the distance between cement particles and the porosity due to capillary pores increases. In the present study, we develop a numerical model based on the embedded discontinuity finite elements to predict the effect of the water-to-cement ratio on the compressive fracture behavior of concrete. Representative 2D plane strain simulations demonstrate that the present method captures the major features of concrete fracture and, particularly, qualitatively predicts the known effects of the water-to-cement ratio on concrete compressive strength.