Abstract
The specific surface area, which is a micro-structure of hydration products, is an important physical property of concrete. It has been clarified that the specific surface area affects mass transferred, adsorption of ions in hardened cement paste and shrinkage of hardened cement paste. These phenomena affect concrete durability. Therefore, the specific surface area of concrete should be estimated accurately in order to estimate the concrete performance.
It was clarified that C-S-H affected the specific surface area of hardened cement paste. However, the specific surface area can not be estimated only by the specific surface area of C-S-H, and it is needed to consider the specific surface area of calcium aluminate hydrates.
The purpose of this study is to clarify the estimation method of the specific surface area of hardened cement paste considering calcium aluminate hydrates. From the experimental results, the relationship between the reaction ratio of C3A and the amount of C3AH6 can be formulated independent of water-binder ratio. Moreover, the specific surface area of calcium aluminate hydrates in hardened cement paste can be estimated by using only the reaction ratio of C3A and the amount of C3AH6. The total amount of AFt, AFm and C4AH13 can be calculated from the reaction ratio of C3A and the amount of C3AH6. The specific surface area of C3AH6 is too small in comparison of those of AFt, AFm and C4AH13. Therefore, the specific surface area of C3AH6 can be negligible when estimating the specific surface area of hardened cement paste. The total specific surface area of calcium aluminate hydrates can be estimated from the total amount of AFt, AFm and C4AH13 without determining amount of each three hydration products can not be estimated quantitatively.
