| 摘要 |
PROBLEM TO BE SOLVED: To obtain a cement composition capable of providing ultra high-early- strength concrete rich in flexural resistance and especially having good strength- developing property at low temperature by blending specific portland cement with anhydrous gypsum, formic acids and steel fiber. SOLUTION: This cement composition contains portland cement having >=60%, 3CaO.SiO2 content, anhydrous gypsum, formic acids and steel fiber and as necessary, silica fine powder. Sufficient initial strength is not obtained if 3CaS content is <60wt.%. Usually, commercial early-strength portland cement can be used. Grains of cement have preferably 3,500-7,000cm<2> /g Blaine value. Sufficient initial strength of the concrete may not be obtained if the Blaine value is >3,500cm<2> and slump loss of concrete becomes often large if the Blaine value exceeds 7,000cm<2> . |
