| 研究実績の概要 |
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 (<0.075 mm in size) to granular particles with diameters of 2.0 to 9.5 mm. According to the hydraulic conductivity tests, the original soil and the amended soil were not significantly different in hydraulic conductivity. This suggests that powder or granular particles of stabilising agent will not significantly impact the hydraulic properties of the attenuation layer. As continuous permeation progressed, the hydraulic conductivity of the soil-agent mixture decreased but remained over 1 × 10-8 m/s. The presence of acidic leachates could delay the attenuation layer's decline 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. Using a stabilising agent with a smaller particle size for the amendment has a greater impact. Kd increases linearly as the particle size of the stabilising agent decreases down to 0.075 mm. Using the Kd from laboratory tests, simulations with a one-dimensional advection-dispersion equation demonstrate the durability of the attenuation layer. Both the powder and the granular particles show promise as attenuation layer materials.
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