| 摘要 |
PURPOSE: To suppress the lowering of fluidity with time and the generation of cracks and improve the early strength of a high-early-strength concrete composition by adding a specific cement dispersing agent to a high-early-strength concrete composition containing specific amounts of a high-early-strength Portland cement, water, fine aggregate and coarse aggregate at respective specific amounts. CONSTITUTION: A cement dispersing agent composed of a water-soluble vinyl copolymer consisting of 45-65mol% of the constituent unit A of formula 1, 2-15mol% of the constituent unit B of formula 2, 5-20mol% of the constituent unit of formula 3 and 10-40mol% of the constituent unit of formula 4 and having a number-average molecular weight of 2,000-20,000 is added in an amount of 0.1-2.0 pts.wt. (based on 100 pts.wt. of high-early-strength Portland cement) to a high-early-strength concrete composition composed of a Portland cement meeting the JIS-R5210, water, fine aggregate, coarse aggregate and a cement dispersing agent and having a water/cement ratio of 30-65%, a water content of 140-180 kg/m<3> , a fine aggregate content of 700-1,200kg/m<3> and a coarse aggregate content of 800-1,200 kg/m<3> . The cement dispersing agent is added together with kneading water in the kneading of the concrete composition. |
