2021 Fiscal Year Final Research Report
Hydraulic and chemical performance of a sandy soil mixed with calcium-magnesium composite as the attenuation layer for geogenic heavy metals
| Project/Area Number |
20K22433
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| Research Category |
Grant-in-Aid for Research Activity Start-up
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| Allocation Type | Multi-year Fund |
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| Review Section |
0303:Civil engineering, social systems engineering, safety engineering, disaster prevention engineering, and related fields
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| Research Institution | Kyoto University |
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Principal Investigator |
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| Project Period (FY) |
2020-09-11 – 2022-03-31
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| Keywords | Attenuation layer / Geogenic contamination / Stabilising agent / Hydraulic conductivity / Sorption / Arsenic / Soil management / Excavated soils |
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| Outline of Final Research Achievements |
This work was carried out to evaluate the attenuation performance and hydraulic conductivity of a soil mixed with calcium-magnesium composite with different particle sizes, ranging from powder particles to granular ones. According to the hydraulic conductivity tests, the original soil and the amended soil were not significantly different in hydraulic conductivity. Batch sorption tests demonstrated that amended soil more effectively attenuates contaminants than the original soil. In one experiment, a stabilising agent of granular particles (between 2.0 and 9.5 mm) for the amendment increased the soil’s partition coefficient Kd from 14.5 to 22.2 cm3/g, which is more than a 50% improvement in the attenuation. Kd increased linearly as the particle size of the stabilising agent decreased down to 0.075 mm. Using the Kd from laboratory tests, simulations with a one-dimensional advection-dispersion equation demonstrated the durability of the attenuation layer.
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| Free Research Field |
Geoenvironmental Engineering
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| Academic Significance and Societal Importance of the Research Achievements |
Since stabilising agent affects the mechanical and chemical properties of the attenuation layer, particle size of agent needs to be optimised as per the site requirements. Soil mixed with agent of different sizes were examined, and powder and granular particles were confirmed as suitable materials.
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