Development of a new land restoration and conservation technology learned from beachrock formation mechanism

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H04404
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Geotechnical engineering
• Research Institution: Hokkaido University
• Principal Investigator: KAWASAKI SATORU 北海道大学, 工学研究院, 教授 (00304022)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: ビーチロック / 炭酸カルシウム / 微生物 / 国土保全

Outline of Final Research Achievements

The purpose of this study was to develop man-made beachrocks cemented by precipitated CaCO3, which were produced by using natural coastal materials. This technique endowed the man-made beachrocks with an unconfined compressive strength (UCS) of approximately 20-30 MPa after approximately one month of curing. The technique was newly developed in this study and validated for its effectiveness.
A search for ureolytic bacteria that yield high urease activity was conducted in coastal areas in Japan. Several types of discovered bacteria that exhibited suitable properties for precipitating CaCO3 were isolated from soil samples in areas such as Okinawa prefecture and Hokkaido. Accelerated laboratory solidification tests on sand samples were performed using the bacteria. The results demonstrated that after three weeks, the samples yielded approximately 20 MPa of UCS as measured in needle penetration tests. In conclusion, the effectiveness of the newly developed technique was validated.

Free Research Field

地盤環境工学

Academic Significance and Societal Importance of the Research Achievements

海岸コンクリート構造物の修復保全時に，コンクリートの材料となるセメントを使用せずにCaCO3を使うことでCO2排出量の削減に貢献できる。また，海岸侵食に対する国土保全に加え，地盤の液状化対策，河川堤防の修復保全などに関する対策技術の選択肢が増えることにつながる。
将来的には，従来のコンクリート製による保全技術ではなく，現地の周辺材料で自然に加速固化する人工岩盤の自己形成・自己修復・自己保全技術としての適用が期待される。