Crack control of concrete caused by thermal-autogenous-drying shrinakges based on constituents

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K04559
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 22010:Civil engineering material, execution and construction management-related
• Research Institution: Ashikaga University
• Principal Investigator: Miyazawa Shingo 足利大学, 工学部, 教授 (10157638)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: マスコンクリート / 水和発熱 / 自己収縮 / 乾燥収縮 / ひび割れ / 温度応力解析 / 自己応力

Outline of Final Research Achievements

FEM thermal stress analysis was performed considering not only thermal shrinkage and autogenous shrinkage of concrete but also drying shrinkage, and the effect of each shrinkage on cracking was investigated. In the thermal stress analysis, a conventional drying shrinkage model based on the capillary tension theory considering the pore size distribution of hardened cement paste was used. The drying shrinkage stress of the concrete specimen was measured by stress releasing method and compared with the stress analysis results. FEM thermal stress analysis was performed using the parameters determined based on the measured drying shrinkage stress. From the results of FEM stress analysis for a wall-type structures with medium thickness, it was found that the wall member was prone to cracking in the central portion due to thermal stress at early ages followed by drying shrinkage cracking on the surface.

Free Research Field

コンクリート工学

Academic Significance and Societal Importance of the Research Achievements

これまで、マスコンクリートのひび割れ発生に対する事前検討や事後解析において、コンクリートの乾燥収縮の影響を定量的に考慮されることは少なかった。特に、部材寸法がそれほど大きくないマスコンクリート構造物では、乾燥収縮の影響が無視できないと考えられることから、ひび割れの発生原因を明確に判断できない事例も少なくないことが懸念される。本研究では、温度収縮と自己収縮のみでなく、乾燥収縮も考慮した温度応力解析結果を示すことがき、その成果は、今後のマスコンクリート構造物のひび割れ制御手法の合理化に資することが期待される。