| 種別 | paper |
| 主題 | Multi-Component Model for Hydration Heat of Concrete Based on Cement Mineral Compounds |
| 副題 | |
| 筆頭著者 | Toshiharu KISHI（Ohbayashi Corporation） |
| 連名者1 | Kazumasa OZAWA（The University of Tokyo） |
| 連名者2 | Koichi MAEKAWA（The University of Tokyo） |
| 連名者3 | |
| 連名者4 | |
| 連名者5 | |
| キーワード | |
| 巻 | 15 |
| 号 | 1 |
| 先頭ページ | 1211 |
| 末尾ページ | 1216 |
| 年度 | 1993 |
| 要旨 | INTRODUCTION Thermally induced crack at early age of concrete is of great interest to engineers involved in durability design and construction of massive structures. Here, it is crucial to accurately predict the thermal expansion associated with temperature rise in structures of young concrete. As a source of temperature rise, the hydration heat of cement in concrete has to be modeled for thermal crack control in the scheme of durability design. Lately, High Performance Concrete, that is, super fluidized and durable concrete being placed into forms without vibrating works, was innovated. This paper aims at the rational predictive method for heat generation of cement in concrete covering High Performance Concrete with small amount of water and wide variety of powders. For making thermal crack control possible in the durability design stage, the heat generation corresponding to the specified mix proportion has to be predicted without any temperature rise test. For meeting the required versatility, we have to take into account the following characteristics of High Performance Concrete. Owing to the super-fluidity without segregation, lower amount of water is specified in general and larger content of powders (cement, pozzolans and rock mineral powders) is essential. The retarded rate of hydration due to lower water content will occur unlike conventional concrete. Furthermore, the model required has to be applicable to ordinary Portland cement (OPC) as well as moderate heat Portland cement (MHPC) and their mixture with pozzolans. In this case, different ratio of constituent minerals of clinker has to be rationally modeled. In meeting the engineering challenge mentioned above, this paper proposes the multi-component model of cement hydration heat based on Arrhenius's law of chemical reaction. The nonlinear coupling of heat generation under lower water content with thermal conduction in structures are also undertaken. CONCLUSIONS The unified hydration heat model of cement in concrete mixes was proposed for a future frame of assuring required functions and durability of structures based on vibration free high performance concrete of super fluidity. The cement clinkers are classified into four minerals with which five patterns of hydration are embodyed. The coupling of free water and temperature, which indicate the thermodynamic environment of cement in concrete, with the hydration rate was taken into account. The hydration model was also experimentally verified. Though plenty of items have to be clarified for crack control design, the structural discussion on the thermal crack risk was made under some simplified conditions. Finally, this research was financially supported by Ministry of Education through Grant-in-Aid for Scientific Research No.04555114. |
| PDFファイル名 | 015-01-1206.pdf |