A two-stage model for the prediction of mechanical properties of cement paste
Siventhirarajah Krishnya, Yuya Yoda, Yogarajah Elakneswaran
Abstract
The mechanical properties such as compressive strength, Young's modulus and Poisson's ratio are the most important parameters for design and structural analysis in the field of Civil Engineering. In hydrated cement paste, these properties are significantly determined by its microstructure. In this research work, a two-stage model is proposed to systematically predict the mechanical properties of the cement paste from the microstructure. In Stage-1, relative humidity, thermodynamic, cement hydration and model for volumetric prediction are integrated to accurately predict the volume fraction of hydration products. Subsequently the Stage-2 proposes a multi-scale model (in three hierarchical levels) initiating from C–S–H matrix considering the formation of two types of C–S–H (low- and high-density C–S–H) to cement paste for the computation of the intrinsic mechanical properties of cement paste. As the volume fraction of C–S–H and capillary porosity are the most significant components which determines the mechanical properties of cement paste, prime consideration herein is given to C–S–H space ratio. The proposed model is well verified at the predictions of relative humidity, chemical shrinkage and capillary porosity in Stage-1; compressive strength, Young's modulus and Poisson's ratio in Stage-2 with independent sets of experimental results.