| 摘要 |
The composition and the method can be used in civil engineering for making of concretes and cement mortars. The composition is concentrated, stable and homogenous at low positive and negative temperatures. Its application allows that the concrete and cement mortars produced by it should quickly reach their preset strength characteristics. The method has lower energy consumption and higher stability and homogeneity of the end product at low positive and negative temperatures. The composition includes, in wt. %: from 38 to 88 melamine, from 18 to 42 urea, from 225 to 260 formalin, from 225 to 255 sodium biphosphate, from 12.4 to 30.6 38% aqueous solution of sodium base and from 6 to 17 50% aqueous solution of formic acid or from 8.4 to 22 50% aqueous solution of acetic acid. The method is realized by condensation. Melanine, formalin, urea, sodium bisulphite and sodium base are mixed and alkaline condensation is performed, after the conclusion of which acid is added and acidic condensation is performed after which the product is alkalized with sodium base and is diluted with water. The mixture includes, in wt. %: from 38 to 88 melamine, from 18 to 42 urea, from 225 to 260 formalin and from 225 to 255 sodium bisulphite. The sodium base is 38% aqueous solution and is added until producing pH from 11 to 11.5. After mixing, the alkaline condensation is performed at temperature range from 70 to 75 degrees C until the full assimilation of the sodium bisulphite. The added acid is limited and is 50% solution of formic acid or acetic acid. The acidic condensation is carried out after reaching pH 5-6 at temperature range from 83 to 86 degrees C until viscosity from 18 to 20 s (4 mm/50 deg. C) is produced, after which the product is alkalized with 38 % aqueous solution of the sodium base to pH 10.5-11 and is diluted with water to dry matter content in the solution from 38 to 42 %. 2 claims
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