| abstract |
A sealing material comprising a water-resistant sheet, wherein the water-resistant sheet comprises layered clay minerals having a thickness of 0.5 nm to 800 nm. A sealing material comprising a sheet, wherein the sheet comprises modified layered clay minerals in which at least a portion of a first cation between the interlayer of swellable layered clay minerals is ion-exchanged with a second cation, in a first cation being one or more selected from Na<sup>+</sup>and Li<sup>+</sup>. A sealing material comprising a sheet, wherein the sheet comprises layered clay minerals having a thickness of 0.5 nm to 800 nm, and having one or more selected from K<sup>+</sup>, Ba<sup>2+</sup>and Pb<sup>2+</sup>are contained in at least a portion in an interlayer of the clay minerals |