Micro-Mechanical Model And Property Evolution For Hydated Media

Present dissertation deals with evolution of effective property and microstructure of hydrous media. The microstructure changes and new components produce when such media are hydrated. The property evolution depending on microstructure in the hydration of the media is studied using homogenization theory and micro-mechanical model established.(1)According to homogenization theory, the relationship between the effective properties and microstructural parameters is built. The composite material is regard as to be an assembly of representative volume elements (RVEs) periodically distributed in space. The periodical boundary conditions for the RVEs are described. The effective properties of the composite materials are calculated by direct average method and two-scale expansion method.(2)As an application, property evolutions in the hydration of cement are investigated. Based on the experimental measurements, a micro-mechanical model is developed to investigate the evolution of the microstructure and effective properties of the cement. The instantaneous Young's modulus and Poisson's ratio of the cement paste are calculated. The numerical results are in good agreement with the experimental data. The present method can be extended to model property evolution of other hydrous media.(3)For the study of the effect of the internal pressure on the property of the materials, two micro-mechanical models are established for the composites with circular pore and elliptical pore. The effective stiffness coefficients of the materials with different internal pressure are calculated and the influence of the geometry of the pore on the effective properties is analyzed.It is shown that the present micro-mechanical models can simulate the evolution of microstructure and properties and reflect the influence of internal pressure on the effective properties. The comparison between numerical results and experimental data shows the validity and effectiveness of the present methods and models, which can be extended to analyze microstructure and property evolution of other hydrous media.