| 摘要 |
PROBLEM TO BE SOLVED: To obtain a hydraulic composition with improved cracking-proofness and mechanical strength such as flexural strength by including a hydraulic material and a polyvinyl alcohol with saponification degree and polymerization degree each of specific level or higher so as to specify the polyvinyl alcohol content of the composition on the whole solid basis. SOLUTION: The saponification degree and polymerization degree of the polyvinyl alcohol are >=80 mol.% and >=1,200, respectively, and the content of the polyvinyl alcohol in this hydraulic composition is 0.1-20 wt.% on the whole solid basis. It is preferable that the polyvinyl alcohol to be used is a silyl group-modified polyvinyl alcohol, a thickening matter (pref. boric acid or borax) is included at 1-20 wt.% based on the polyvinyl alcohol, reinforcing fibers (pulp is also used other than Vinylon-based fibers) are included at 0.1-10 wt.% on the whole solid basis, and the degree of the silyl group modification is 0.1-10 mol.%. The hydraulic material is an organic matter such as one of various kinds of Portland cement or gypsum. This hydraulic composition is used as a molding material for roofs, external walls, board-like materials for inner walls, roads, shore protective blocks and others. |
