Patent RU-2207995-C2 (RU)
Title: Method of manufacturing low water-demand cement
Inventor: JUDOVICH B EH
IPC: C04B7/52
Filed: 2001-06-21
Granted: 2003-07-10
Abstract: FIELD: manufacture of building materials. SUBSTANCE: method consists in mechanic-chemical treatment, in particular common grinding to specific surface 400- 700 sq.m/kg, of Portland cement clinker with calcium sulfate ingredient and modifier, the latter including hardening accelerator and organic water-reducing agent. More specifically, Portland cement clinker is granulated product of cement raw mill firing comprising alkali metal sulfate and carbonate admixtures, which admixtures are fired in the form of hardened surface granules, drops, and leakages of anhydrous compounds and/or needles and joints of their crystal- hydrates joined during common grinding of the above-indicated ingredients to form salt phase of hardening accelerator in organic reagent in amounts 10 to 50% of the weight of the latter. Common grinding is effected at ratio of the above- indicated ingredients 100:(1-7): (0.6-2.5), respectively, until stoichiometric amount of alite phase in surface layer of cement clinker particles is attained. This moment and, correspondingly, grinding end moment is found from degree of aggregation of cement particles equal to 5-15 vol % at hygroscopic moisture no higher than 3%. Portland cement clinker may contain alkali metal compounds calculated as   in amounts 0.3 to 1.4 wt % and sulfur trioxide 0.4 to 1.5 wt %. The following materials are used (in amounts 0.6 to 2.5% of the weight of Portland cement clinker) as organic water-reducing agent: alkali and/or alkali-earth metal salts of naphthalenesulfonic acid/formaldehyde condensation product or melamine-containing resins/formaldehyde condensation product; complex salts of alkali-earth metals and sulfuric and/or nitric, and/or formic, and/or acetic acid with low- molecular C3-C5-monosaccharides; or mixtures of indicated materials at weight ratio from 4:1 to 1:4. Calcium sulfate ingredient utilized is gypsum dihydrate or its mixture with gypsum semihydrate at weight ratio from 1:0.01 to 1:2, or gypsum dihydrate/anhydrite mixture (1:0.01 to 1:0.2), or mixture of gypsum dihydrate with following chemically modified gypsums: phosphogypsum, titanogypsum, fluoroanhydrite, and product of limestone treatment of sulfur- containing leaving gases from industrial furnaces and/or reactors taken at weight ratio from 1: 0.05 to 1:1 in amounts between 0.01 to 3 wt %. Cement is further supplemented by active mineral additive and/or filler introduced by common or separate grinding at ratio to cement from 5:100 to 850:100 at hygroscopic moisture 0.01 to 3%. Additive is composed of one or two components selected from granulated blastfurnace slag, fuel slag, fly ashes, volcanic ashes, pumice, tufa, quartz sand, feldspar sand, granite crushing screenings, ore-dressing tails, broken glass, broken bricks, keramzit or glass- keramzit dust, and active silica, in particular crushed, granulated, or ground silicate block in amounts 0.2 to 20% of the weight of cement, powdered or granulated microsilica (0.2 to 10%), said microsilica containing plasticizing component introduced during granulation in amounts 0.001 to 0.2% of the weight of cement. EFFECT: increased aggregative stability and looseness of cement, prevented its caking and ageing. 7 cl, 2 tbl