A new ground improvement technique by calcium carbonate precipitation

2019 Fiscal Year Final Research Report

• Project/Area Number: 18K18213
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 64020:Environmental load reduction and remediation-related
• Research Institution: Waseda University
• Principal Investigator: Takaya Yutaro 早稲田大学, 理工学術院, 講師(任期付) (10636872)
• Project Period (FY): 2018-04-01 – 2020-03-31
• Keywords: 地盤改良 / 炭酸カルシウム / CCS/CCU技術

Outline of Final Research Achievements

The purpose of this study is to establish a new ground improvement technique by the dissolution and re-precipitation of shelly fossils (calcium carbonate) in a sea sand. We demonstrated that the strength of simulated sea sand exceed 30 kg/cm2 by adding and re-precipitation of 1% calcium carbonate. SEM/EDS observations revealed that the strength improvement of sea sand was accompanied by filling intergranular pores of sea sands with small calcium carbonate and acicular trona (sodium carbonate). The treated samples were strong enough for the practical use but gradually lost their strength by a water immersion. Therefore, the challenge for the practical use for this ground improvement technique is to reinforce the water resistivity of treated sea sand samples.

Free Research Field

地圏物質科学

Academic Significance and Societal Importance of the Research Achievements

本研究では炭酸カルシウムの固着を用いる新しい地盤改良技術の構築を目指した．現場の海砂に含まれる貝化石を炭酸カルシウム源とすることで，環境影響を低減することが従来の手法とは大きく異なる点である．地盤改良の再現実験では，炭酸カルシウム含有量1％で高い強度を発現することが確認されたが，水に弱いという弱点があり耐水性を向上させることが実用化に向けた大きな課題であることが示された．