Microstructure and Behavior of Allophane

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The peculiarity of physical and engineering properties of volcanic ash soil are attributed to the character of allophane and it's microstructure. Therefore, investigation was made on the microstructure and behavior of allophane suspension. The results are as followes.1. Changes of viscosity, turbidity, and microstructure of allophane by air-drying. (1) The dispersivity of allophane suspension is largely affected by the slight change of physico-chemical properties on allophane surface by air-drying under the neutral and alkaline suspension. (2) Nevertheless, the change of the physical and engineering properties of volcanic ash soil by air-drying is considered to be caused by the aggregation of allophane under the natural soil condition (about pH 6). (3)The fact mentioned above was confirmed by the electron microscopic examination.2. The influence of free sesquioxide on the dispersivity of allophane suspension. (1) The season why the non-defferated allophane does not disperse under the alkaline condition cannot be explained by the net particle charge. (2) And the phenomenon was considered to be caused by the rise of isoelectric point, direct interactive function of aluminum polymer, and the heterogenenity of the charge distribution on the allophane surface. (3) Aluminum is considered to be more active agent than iron on the soil flocculation.