Mechanical behavior comparison of single and multiple phase models for cement paste using micro-CT images and nanoindentation

The behavior of cement paste is significantly affected by the phase distribution characteristics within the material. However, studying the correlation between the microstructural characteristics and intrinsic properties involves time-consuming experiments. Thus, simulations can help accelerating the process. In this study, a method using micro-CT imaging analysis and nanoindentation within the framework of finite element analysis was proposed to investigate the mechanical properties of the cement paste. The virtual specimen obtained from micro-CT was segmented into four phases: pore, inner and outer hydration products, and unhydrated cement. Subsequently, the material modeling input parameters for each solid phase were determined using a nanoindentation test. The differences in the crack patterns and mechanical properties of the homogenized single and multiple phase solid models were confirmed. In addition, the localized characteristics of crack propagation in the multiple phase solid model were detected, which enable it to reflect a more realistic behavior than the single phase solid model. The modeling input parameters for the outer hydration product, which is the dominant phase of the multiple phase solid model, can be used as a first approximation to predict the microstructural response at reduced computational cost.