Research on effective use of organic soil and volcanic ash cohesive soil as soil cover and adsorption layer

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K04690
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 22030:Geotechnical engineering-related
• Research Institution: Kyushu Sangyo University
• Principal Investigator: Hayashi Yasuhiro 九州産業大学, 建築都市工学部, 教授 (50274692)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 重金属類 / 不要化 / 六価クロム / 有機質土 / 火山灰質粘性土 / フライアッシュ / 長期環境安全性

Outline of Final Research Achievements

Focusing on the substance adsorption capacity of organic soil and volcanic ash cohesive soil, which have not been effectively utilized, research was conducted to utilize them as a covering layer and adsorption layer for disaster wastes and the like. Fly ash was selected as the waste material, and hexavalent chromium was selected as the toxic substance. When fly ash was mixed with soil, a higher concentration of hexavalent chromium was eluted than when fly ash was mixed alone. This was considered to be due to the fact that the organic matter and allophene contained in the soil, especially the latter, made the hexavalent chromium in the fly ash more easily leachable, and the soil was unable to sufficiently adsorb the anionic hexavalent chromium.

Free Research Field

地盤工学

Academic Significance and Societal Importance of the Research Achievements

有機質土や火山灰質粘性土は強度レベルが低いため，土構造体としての利用は厳しいが，物質吸着能に着目することで災害廃棄物などの覆土層，吸着層として利用できれば発生土の有効利用に寄与できると考えた。フライアッシュは石炭火力発電で発生する産業廃棄物であり，有害重金属類を含有するため処分費が高い。そこで，フライアッシュを対象に有機質土や火山灰質粘性土による重金属類不溶化が可能であれば資源の有効活用に寄与できると考えた。しかし，これらの材料を混合することによる相互効果が重金属類の溶出に悪影響を及ぼすことが示唆され，今後のさらなる研究が必要であることが明らかになった。