PRODUCTION OF HYDRAULIC HARDENED FORM

摘要

PROBLEM TO BE SOLVED: To obtain a hardened form excellent in flexural strength, impact resistance, dimensional stability and durability by curing treatment of a mixture comprising a polyvinyl alcohol-based fiber having a specific internal crosslink index and a hydraulic material so as to afford a specific flexural strength followed by conducting an autoclave treatment. SOLUTION: This hardened form is obtained by curing treatment at a temp. of 60-100 deg.C of a mixture comprising a polyvinyl alcohol (PVA)-based fiber >=75 in internal crosslink index and a hydraulic material (e.g. Portland cement) so as to afford a flexural strength of 35-70 kg/cm<2> followed by conducting an autoclave treatment at a temp. of 130-180 deg.C. For the PVA-based fiber, the PVA polymer as its raw material is pref. >=1,500 in viscosity-average polymerization degree and >=98 5 mol.% in saponification degree, and the PVA polymer concentration of the spinning dope is pref. 5-50 wt.%, the temperature of the spinning dope being normally 40-230 deg.C. The aspect ratio of the PVA-based fiber is pref. 150-1,500. The amount of the PVA-based fiber to be incorporated in the final hydraulic molded form is set at 0.1-10 wt.%.