Size-dependent fracture behavior of steel fiber reinforced cement mortar modified by polymer

According to various engineering scenarios, selecting the appropriate sizes and comprehending the mechanisms governing damage and fracture in cement-based materials are of significant importance in structural design. However, the damage and fracture characteristics of cement-based material with varying sizes have not been clearly elucidated. A power law relationship model with an index of 0.5 was developed in this study to describe the damage rate and size effect on steel fiber reinforced cement mortar modified by polymer, based on finite element model and experiment for three-point bending specimens. The consistency between experimental and simulation results indicated that the flexural strength decreases with increasing. It was observed that with increasing size, there was an acceleration in damage, suggesting a shift towards brittle fracture. Simultaneously, the count of primary cracks decreased and stabilized, while the crack area expanded. A significant size effect was observed within the thickness range of less than 40 mm, while the flexural strength plateaued beyond this threshold. And the process of crack damage evolution can be well captured by mesoscopic numerical model. By utilizing the scaling law and regression analysis, the size effect on the flexural strength was investigated.