| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To develop a new technology that effects a precast concrete product having a high quality by reducing environmental load by utilizing an industrial waste, typically, fly ash. <P>SOLUTION: The cement fine powder is composed of a fine powder of ordinary portland cement on the surface of which C3A appears, and which presents a spherical shape having a specific surface area of 6,500 cm<SP>2</SP>/g or larger and a diameter of 0.001-20μm, and to which a dispersion aid is added. Using this fine powder, a composition for precast concrete which contains ordinary portland cement, a fine powder of fly ash and the cement fine powder and which has a substitution rate of the fine powder of fly ash to the portland cement of 60 wt.% or lower and a substitution rate of the cement fine powder to the portland cement of 5 wt.% or lower is obtained. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
