1990 Fiscal Year Final Research Report Summary
Evaluation of Accumulated Damage in Reinforced Concrete at Early Age
| Project/Area Number |
01850107
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Research Field |
コンクリート工学・土木材料・施工
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| Research Institution | University of Tokyo |
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Principal Investigator |
OZAWA Kazumasa Univ. of Tokyo, Dept. of Civil Engg., Assist. Lecturer, 工学部, 助手 (80194546)
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| Co-Investigator(Kenkyū-buntansha) |
UEDA Tamon Univ. of Tokyo, Dept. of Civil Engg., Assoc. Prof., 工学部, 助教授 (00151796)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Hydration, / Temperature-dependency, / Activation energy, / Accumulated damage / Water movement, / Drying shrinkage, / Durability, / Early-age concrete |
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| Research Abstract |
The objective of this study is to evaluate the accumulated damage and micro fracture in concrete caused by hardening and drying shrinkage, heat and water transfer and external stress at early age, and to develop the new system for evaluating the time-dependent performance for durability of concrete structures.
1. Time-dependent and path-dependent hydration of cement
The evaluation method for activation energy of cement in concrete was developed. The model for path-dependent hydration of cement at any temperature and any any age was proposed.
2. Activation energy and mix proportion
It was clarified that the activation energy representing temperature dependency of cement is controlled by the dispersion of cement in concrete. General relationship between mix proportion and activation energy was successively proposed.
3. Evaluation of accumulated damage
Evaluation method of accumulated damage caused by hardening and drying shrinkage and segregation in cover concrete around reinforcing bars was proposed with use of tension-stiffness of concrete. Resistance to the damage was also successively evaluated by average tensile strength, average tensile plastic deformation and bond deterioration.
4. Water movement and drying shrinkage in concrete
Model for predicting water movement in concrete at fresh state and after being hardened was proposed, which affects the damage and micro fracture in concrete. Relationship between water movement by drying and shrinkage in concrete was clarified based on the micro-structure of concrete.
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