| 摘要 |
PROBLEM TO BE SOLVED: To obtain a cement-modifying agent contriving to prevent the freezing of cement milks, improve the strength of cured cement products and prevent the generation of cracks in the cured cement products by including fibers to which a sizing agent is adhered. SOLUTION: The fibers used therein include synthetic fibers such as polyester fibers and polyethylene fibers and natural fibers such as pulp, cotton, wool and silk, but are preferably polyester fibers. The sizing agent includes warp- sizing agents and finishing sizing agents, such as starch, polyvinyl alcohol and an acrylic sizing agent, preferably a polyacrylate ester. The polyacrylate ester include the copolymers of one or more kinds of acrylate esters such as methyl acrylate and ethyl acrylate with one or more kinds of copolymerizableα,β-unsaturated aliphatic acids. It is necessary that the copolymers are neutralized with ammonia or sodium hydroxide and are produced in sufficient copolymerization ratios so as to give water solubility or water dispersibility. If necessary, a surfactant is added. |
