| 摘要 |
<p>PURPOSE:To produce cement having a low heat of hydration and a high strength by blending vitreous blast-furnace slag regulated to specified fineness with portland cement at the prescribed rate and regulating the ratio of heat of hydration to strength of cement. CONSTITUTION:Fineness of vitreous blast-furnace slag is regulated to three thousands to ten thousands cm<2>/g (addition of gypsum is <=5%) Blaine's specific surface area. The degree of blending with various kinds of portland cement is regulated to 40-90%. Thereby the ratio of heat of hydration (cal/g) of cement to compression strength (kgf/cm<2>) thereof is regulated to 0.43-0.13 in 7 days and to 0.24-0.1 in 28 days. The effect for utilizing vitreous blast-furnace slag is not generally exhibited in lowering of heat of hydration at the degree of blending less than 40%. This effect is made more remarkable as the degree of blending exceeds it and is made great. When the degree of blending exceeds 90%, strength is made difficult to be exhibited. Therefore a specific means for promoting hydration such as aging is necessitated. As fineness, practical strength is made difficult to be maintained in the case of Blaine's specific surface area less than three thousands cm<2>/g. When the Blaine's specific surface area exceeds ten thousands cm<2>/g, hydrating reaction is made excessively quick, and kneading and transportation are made difficult when the blended substance is utilized for concrete.</p> |
