Abstract
This thesis is concerned with the calcium silicate hydrates（CSH）, which is the main structural phase of most concrete and consist of crystalline minerals and the extremely variable and poorly ordered phase. The structure of CSH is amorphous and changes with time. Thus, the structure of CSH has been estimated from the results of various instruments. However, almost all models of CSH focused on stabilized structure, and only few researches focused on the nanostructural formation process of CSH with time. Therefore the purpose of this thesis is to understand the nanostructural formation process of CSH. In this research, three instruments were employed. First, the amount of dissolved cementitious minerals was measured by X－Ray Diffraction（XRD）/Rietveld analysis. Second, the polymerization of silicates was measured by Tri－methyl－sililation（TMS）. Finally, the chemical environment of silicates, such as neighbor ions was measured by NMR. As the result, after mixing water and cement, cementitious minerals dissolved and existed in the transitional state, that is the state including dissolution monomer of silicate. Its state made up about 30％ of the calcium silicate dissolved when the percentage of calcium silicates reacted became 50％, and existed also the same amount for long period. In addition, it became clear that the long－period average silica chain length is equal to the short－period one. In brief, around the same time that the transitional state reached saturation, the nanostructure of CSH began to be formed. Therefore, it suggested that the short－period formed C－S－H exercises considerable influence over the long－period one.
