Patent RU-2213070-C1 (RU)
Title: Cement raw meal, method of manufacturing portland cement with lowered shrinkage from portland cement clinker obtained by fire caking of indicated raw meal and a method for manufacturing cementing material suitable to repair concrete and to strengthen grounds being fine fraction of indicated portland cement
Inventor: JUDOVICH B EH
IPC: C04B28/02
Filed: 2002-03-22
Granted: 2003-09-27
Abstract: FIELD: manufacture of building materials. SUBSTANCE: invention can be applied in cement production, building industry, geotechnical and hydroengineering construction, and in restoration operations. Cement raw meal, containing lime, silicate, and ferrous ingredients as well as 0.03 to 0.5% of strontium compounds (calculated as oxide), alkali metal oxides, and sulfur trioxide, contains its strontium compounds within lime ingredient in the form of calcite-strontianite (strontianite, celestine) and with silica modulus of mixture 0.5-1.25 and weight ratio of alkali metal oxides (calculated as sodium oxide) to sulfur trioxide equal to 0.7-1.5. Raw meal further contains 0.15 to 0.5% barium compounds (silfide, whitherite, barite calculated as barium oxide). Lime saturation ratio of clinker is 0.9-1.15. This raw meal is caked by firing in oxidative atmosphere until contents of 0.05-0.8% free calcium oxide and 0.01-0.3% iron monoxide are obtained. Resulting clinker is jointly ground with gypsum component at weight ratio 100: (0.3-6), respectively, to achieve specific surface 250-700 sq.m/kg (taking into consideration criterion of minimum shrinkage of samples made from cement paste in wet air medium). Gypsum component is calcium sulfate in the form of naturally-occurring gypsum stone including 0.01 to 1.5% clayey admixtures. When grinding, 0.5 to 40% active mineral agent with 6-12% moisture and moisture-reducing component are added, weight ratio of clinker to this component being 100:90.3- 2.5). Moisture-reducing component is selected from following group: salt of product prepared by condensation of naphthalenesulfonic acid with formaldehyde or melamine-containing resins with formaldehyde; industrial- grade lignosulfonate optionally modified by phenol-formaldehyde resin; complex salts of alkali-earth metals and acid (sulfuric, formic, acetic acid) with low-molecular (C3- C5) monosaccharides; and paired mixtures of indicated materials. Grinding is carried out in vented disintegrator at aspiration degree controlled by absence of dusting at inlet mouth and in presence of expansion agent added at weight ratio of clinker to that agent 100:(0.5-4). Expansion agent is preliminarily prepared mixture of sulfoaluminate clinker or aluminum sulfate, film-former, and etching agent, said film-former being waterproofing agent selected from higher fatty acids, drying oil, wax, vegetable oils, and solutions of any of indicated materials in mineral oil, and said etching agent being selected from puruvic acid, levulinic acid, mesoxalyc acid, aldonic acids, aromatic acids, their acid derivatives, unsaturated carboxylic acids, hydroxyacids, carbocyclic compounds, dicarboxylic compounds, anhydrides of indicated acids, resin acids in double mixtures with above-indicated substances, alcohols, aldehydes, double and triple mixtures of indicated substances (secondary products and wastes containing thereof), the three agent components being taken at weight ratio 100:(2.5-30):(2-20), respectively. Cementing material for repairing concrete and strengthening grounds is obtained as aspirated and then precipitated material when performing grinding in vented disintegrator, its specific surface being 400-2500 sq.m/kg. Composition of this fraction is controlled by varying ratio of components in Portland cement and mechanical conditions of disintegrator operation until content of strontium and barium compounds achieves 0.2- 0.6%. EFFECT: reduced shrinkage of Portland cement in absence or at reduced content of expansion agent and increased strength of cementing material. 18 cl, 2 tbl, 3 ex