Effect of individual phases on multiscale modeling mechanical properties of hardened cement paste

As the input parameters in multiscale modeling the effective elastic modulus of the hardened cement paste, the elastic moduli of individual phases are crucial for assuring the accuracy of the homogenization estimate. In this study, the mechanical properties and the fractions of individual phases are measured by nanoindentation and back scattered electron image analysis, respectively. The mechanical properties of the hardened paste at microscale are measured by microindentation. The effect of individual phases including the CSH, the residual clinker and the capillary pore on the effective modulus of the hardened cement paste is quantified. It is found that the effective modulus of pore needs to be set as 12 GPa rather than 0 GPa as the input for homogenization. As for the solid phases, the variation of the clinker modulus has limited influence on the homogenized modulus of the hardened cement paste. Whereas, the homogenized paste modulus increases significantly with the increasing fraction of high density CSH and the decreasing fraction of low density CSH. The results of this study can help to select appropriate input parameters for multiscale modeling the mechanical properties of cementitious materials.