Expansive Behavior of Mortars Containing Surf Clam Shell Powder by low curing temperature

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K04336
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 22020:Structure engineering and earthquake engineering-related
• Research Institution: Tomakomai National College of Technology
• Principal Investigator: Akio Watanabe 苫小牧工業高等専門学校, 創造工学科, 准教授 (00422650)
• Co-Investigator(Kenkyū-buntansha): 近藤 崇 苫小牧工業高等専門学校, 創造工学科, 教授 (50290672)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: 膨張 / 収縮 / ASTM C1698 / 拘束 / 低温養生

Outline of Final Research Achievements

The shrinkage of mortar gets reduced in the case where an appropriate amount of expansive material is added to the mortar. Chemical prestress is introduced when restraining the mortar that has been expanded beyond the amount of contraction. The expansion of the mortars at early age were evaluated by conducting length change tests using a corrugated mold based on ASTM C1698. For a difference in curing temperature, the higher the temperature reached, the greater the expansion was made. The amount of cement was replaced with expansive material into a steel load-bearing formwork, we sealed and cured it in a restrained state. We removed the material from the mold on the 7days of age, and conducted the compressive strength test. The strength of mortars which used the steel load-bearing formwork increased at any temperature.

Free Research Field

コンクリート工学

Academic Significance and Societal Importance of the Research Achievements

本研究は，コンクリートの収縮によるひび割れ発生の防止を目的として，膨張性の材料を使用する研究である。膨張性の材料は，膨張材と呼ばれ，カルサイト型炭酸カルシウムである石灰石を主原料としている。石灰石の代わりに貝殻を原料とする炭酸カルシウムの利用について検討を行った。ホッキ貝殻はアラゴナイト型の炭酸カルシウムであり，カルサイト型と比較して膨張能力が高い。そのため，低添加で所定の膨張能力を与えることができる。貝殻のリサイクルの観点と，膨張材の高性能化に貢献できることが本研究の意義である。