Study on shrinkage behavior of cementitious materials with large addition of calcium nitrite under restraint conditions

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K14753
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Building structures/Materials
• Research Institution: Kitami Institute of Technology
• Principal Investigator: CHOI HEESUP 北見工業大学, 工学部, 准教授 (70710028)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 寒中コンクリート / 亜硝酸カルシウム / 硝酸カルシウム / 膨張 / 収縮 / ひび割れ

Outline of Final Research Achievements

In recent years, the use of calcium-nitrite and calcium-nitrate as the main component of salt- and alkali-free to anti freezing agents has been increasing for the purpose of promoting concrete hydration in cold weather concreting. As the amount of nitrite based accelerators increases, the hydration of C3A, C3S and βC2S in the cement is promoted, thereby improving early strength and effectively preventing the initial frost damage. In this study, author experimentally investigated shrinkage, crack initiation and development of mortar containing a large amount of nitrite-based cold-resistant accelerator. As a result, it is considered that the addition of a large amount of nitrite-based cold-resistant promoter accelerates the hydration of C3A, C3S, and βC2S in the cement, therefore the initial shrinkage of mortar is earlier. And, it is confirmed that the larger shrinkage caused cracks more easily than those without the addition of the nitrite-based cold resistance promoter.

Free Research Field

建設材料

Academic Significance and Societal Importance of the Research Achievements

-学術的意義：耐寒促進剤の多量添加によるコンクリートのひび割れ挙動の理論的な解明とそのコンクリートの膨張収縮挙動に関する正確な予測は，当該研究分野の進歩に大きく貢献する研究であると考えられる。
-社会的意義：厳冬期で，特殊性がある耐寒促進剤の多量添加コンクリートのひび割れ予測最適化手法を提案することは，そのコンクリートのひび割れ挙動によるコンクリートの耐久性を高めることで社会資本である厳冬期の鉄筋コンクリート造建造物の適正運用にも大きく貢献できると考えられる。