| 摘要 |
PROBLEM TO BE SOLVED: To provide an additive for a cement composition, which can impart excellent water retentivity and shape retention not influenced by temperature or pressure. SOLUTION: The additive for a cement composition has viscosity (23°C) of 20-1,000 mPa×s and contains a polymer having 45μm screen filterability (25°C) of 0.5-10 wt.% and 45μm screen filtration cleanability (25°C) of 0.2-2 wt.%. The viscosity is determined according to JIS K7117, by measuring a sample (Sa) having a concentration adjusted to 0.5 % with an aqueous 1% calcium chloride solution. The 45μm screen filterability is determined as follows: 500 g of Sa is poured onto a screen having an aperture of 45μm and a diameter of 150 mm; after draining for 15 min, the weight (Z1) of a filtration residue on the screen is measured; and the filterability is calculated with formula (1). The 45μm screen filtration cleanability is acquired as follows: the filtration residue is cleaned by pouring 3L of deionized water; after draining for 15 min, the weight (Z2) of the filtration residue on the screen is measured; and the filtration cleanability is calculated with formula (1). COPYRIGHT: (C)2005,JPO&NCIPI
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