| 摘要 |
PURPOSE:To provide the subject steel materials wherein steel materials are coated with alkali metal silicate (water glass), thereby to provide steel materials excellent in a rust-preventing property, which do not rust in ferroconcretes. CONSTITUTION:Hardened concretes in ferroconcretes are subjected to the effects of carbonic acid gas, and gradually lose alkalinity, and are neutralized. Then, ferroconcretes are corroded and rusted by the effect of moisture containing oxygen and that of carbonic acid gas, and the concrete structure loses its durability. Therefore, ferroconcretes are coated with alkali metal silicate. For alkali metal silicate, ordinarily market-sold water glass such as sodium metasilicate or the like is used. Alternately, it is obtained by heating a mixture consisting of the above described alkali metal salt, aluminum and a phosphatic substance and having the mole ratio of P2O5/Al2O3 of 1 to 6 at a temperature in the range of from 90 to 450 deg.C. The ferroconcretes are further coated with a hardening composition containing aluminum phosphate, whereby corrosion of ferroconcretes can be prevented by the neutralization of concretes. |
