Abstract
The performances of concrete are influenced by the microstructure of hardened cement paste. The microstructure of hardened cement paste is affected by the hydration products. Therefore, in order to evaluate the characteristics of the microstructure of hardened cement paste, the physical properties of hydration product should be clarified accuracy.The purpose of this study is to evaluate the amount of adsorbed water in cement paste. The composition（C/S ratio, the H/S ratio）and the amount of adsorbed water of C-S-H were estimated by using synthesized C-S-H and C-S-H generated from synthesized alite paste. In addition, the amount of adsorbed water of calcium hydroxide and calcium aluminate hydrates were estimated by using synthesized hydration products. Furthermore, the amount of adsorbed water of hardened cement paste also was measured.From the experimental results, the H/S ratio of C-S-H under each relative humidity is proportional to the C/S ratio independent of the mix proportion and curing temperature. From these results, the relation equation between the C/S ratio and the amount of adsorbed water of C-S-H was proposed. The amount of adsorbed water calculated from the relation equation of C-S-H is good agreement with the amount of adsorbed water of the synthesized C-S-H. In addition, the amount of adsorbed water of calcium aluminate hydrates, such as ettringite, monosulfate and C4AH13 were higher than that of calcium hydroxide and hydrogarnet. Moreover, the amount of adsorbed water of hardened cement pastes can be calculated from the amount of hydration products and each amount adsorbed water of hydration products.
