| 摘要 |
PROBLEM TO BE SOLVED: To make a low permeability material sufficiently swell by preventing it from drying and contracting and make exhibit imperviousness even if a crack occurs by providing a curing layer that prevents drying and contraction over an impervious layer. SOLUTION: The first impervious layer 21 as a strengthened backing layer made up of bentonite 6, a solidification material and aggregate, is placed in a state of covering a recessed excavated portion 1a. The second impervious layer 22 where an electrolytic bentonite 6a that absorbs water and swell enough even in cement containing calcium ions is used as a low permeability material is placed over the impervious layer 21. Furthermore, by applying an asphalt emulsion to the surface of the impervious layer 22, a curing layer 23 to prevent drying and contraction of the impervious layers 21 and 22 is provided. As the asphalt emulsion of the curing layer prevents the water molecules of the impervious layers 21 and 22 from evaporating, the impervious layers 21 and 22 solidify in a moist state containing a lot of water molecules, preventing drying and contraction during and after curing, thereby exhibiting imperviousness for a long period.
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