RU2370465C1 - Slag-lime binder graund m and method of producing said slag-lime binder - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to industrial construction materials. The method involves dehydration of volcanic ashes and blast furnace or electrothermophosphorus granulated slag in horizontal type drying drums or pneumatic driers at 150-250°C, cooling in refrigerators to 20-85°C, dosing the said slag and ash and technical modified lignosulphonate - LST-M with averaging of composition in a continuous running screw mixer, grinding the obtained mixture in a centrifugal-impact action grinder to a fraction with particle size 0-80 mcm and specific surface area 2800-5000 cm²/g while returning the fraction greater than 80 mcm separated in continuous running air classifier for re-grinding and subsequent mixing with an alkaline activator containing, wt %: 20-25% aqueous solution of sodium hydroxide NaOH or caustic soda 20-75, liquid glass with density 1.15-1.26 g/cm³ 25-75, with the following ratio of components, wt %: said slag 81.80-94.20, alkaline activator (per dry substance) 3.85-7.27, volcanic ash 1.92-9.09, LST-M (per dry substance) 0.2-1.5% of the mass of said slag and ash (over 100%). Binder, obtained using the method described above.

EFFECT: increased compression strength of binder, control of initial setting of slag-lime dough and prevention of efflorescence of the alkaline component of the binder on the surface of objects made form solutions and concrete.

2 cl, 6 tbl

Description

The invention relates to the building materials industry and, in particular, to the slag-alkali binders used for the production of mortars, concrete and reinforced concrete products and the technology for their preparation and can be used in the manufacture of concrete and mortars for various purposes.

There is a method of producing slag-alkali binders by grinding granular slag in mills of various types, followed by mixing the grinding product with alkaline solutions (Glukhovsky VD Gruntosilikatno virobi i design. Kiev, Budivelnik, 1967, p. 218).

The disadvantage of this method is the low hydraulic activity of binders during hardening in vivo and water. On the surface of concrete and mortar, when moistened and dried, salts of alkaline binder component are formed.

Closest to achieving this goal is a method of producing a binder (RU 2273610, С04В 7/153, publ. 04/10/2006), including grinding slag with an additive that increases the hydraulic activity of the binder, followed by mixing with a solution of water glass, and use the specified additive aluminosilicate additive - siliceous zeolite-containing rock of the Tatar-Shatrshanskoye field of the Republic of Tatarstan or liquid glass production waste from siliceous zeolite-bearing rocks of the Tatar-Shatrshanskoye field of the Republic of Tatarstan, or crumb synthetic zeolite - waste product "Salavatnefteorgsintez" at a ratio of components, wt.%:

Slag and specified additive

with their ratio 1: (0.05-0.1) 70-75

Liquid glass 25-30

The disadvantage of this method of producing a binder is the uneven distribution of condensed silica over fractions of granulated slag, and silica is concentrated on particles with a size of 40-80 microns with stirring in a mixer at the stage of preparing a slag-alkali solution or concrete. Aggregation of silica occurs around larger particles of granulated slag. The alkaline hardening activator - liquid glass - is introduced into the binder in the following sequence. First, liquid glass dissolves in water with vigorous stirring, after which the solution is adjusted to a predetermined density and then only mixed with ground slag and condensed silica fume at the stage of preparation of the concrete mixture. The heterogeneity of the structure of the binder leads to a decrease in physical and mechanical properties and does not make it possible to adjust the setting time of the cinder-alkaline binder, which leads to a decrease in strength and shorten the setting time of the cinder-alkaline test at the initial stage of hardening.

Known binder containing granulated blast furnace slag and an alkaline component - soda ash (Alkaline and alkaline-alkaline earth hydraulic binders and concrete / Ed. By V. Glukhovsky - Kiev .: Vishka school. - 1979. - 218 p.).

The disadvantage of this type of binder is its low compressive strength.

Closest to the invention is a slag-alkali binder (Patent RU 2289551, С04В 7/153, publ. 2006.12.20) containing granulated blast furnace slag, soda ash technical and siliceous additive, and as a siliceous additive contains silica fume, condensed in the following ratio of components, wt.%:

Granulated blast furnace slag (GOST 3476-74 "Granulated blast furnace and electrothermophosphoric slags for the production of cements") 92.3-95.2

Condensed silica fume (TU 5743-048-02495332-96) with a specific surface area of 15000-25000 m / kg - manufactured by the Chelyabinsk Electrometallurgical Plant) 1.3-4.6

Technical soda ash (GOST 5100-85, manufactured by Sterlitamaksky JSC “Soda” with a density of 1150 kg / m ³ ) in terms of dry matter 3.1-3.5.

The disadvantage of the above binder is low compressive strength, quick setting. In addition, soda effusions are formed on the surface of concrete and mortars.

The invention is aimed at increasing the strength of a binder under compression, regulating the start of setting of slag-alkali dough and eliminating efflorescence of the alkaline component of the binder on the surface of products from mortars and concrete.

The purpose of the invention is to reduce the cost of the binder, reducing the process of regrinding and aggregation of mineral particles of the binder, eliminating efflorescence on the surface of concrete and mortar during wetting and drying, adjusting the setting time of the slag-alkali dough and the rate of curing, maintaining high activity of the binder in time and improving physical and mechanical properties.

The technical result in the claimed invention is achieved by the fact that the method of producing a slag alkali binder includes dewatering volcanic ash and granulated blast furnace or electrothermophosphoric slag in horizontal type drying drums or pneumatic conveying dryers at a temperature of 150-250 ° C, cooling in refrigerators to a temperature of 20-85 ° C, dosing of the specified slag and ash and technical modified lignosulfonate - LST-M with averaging of the composition in a continuous screw mixer, grinding the resulting mixture in a centrifugal impact mill to a fraction of 0-80 μm and a specific surface area of 2800-5000 cm ² / g with the return to this fraction of more than 80 μm separated in a continuous air classifier and subsequent mixing with an alkaline activator composition, wt.% : 20-25% aqueous solution of sodium hydroxide NaOH or soda ash 20-75, water glass with a density of 1.15-1.26 g / cm ³ 25-75 in the following ratio, wt.%:

Specified Slag 81.80-94.20 Alkaline activator (dry) 3.85-7.27 Volcanic ash 1.92-9.09 LST-M (dry matter) 0.2-1.5% by weight of the specified slag and ash (over 100%),

and, accordingly, cinder-alkaline binder, which is characterized in that it is obtained in this way.

For the manufacture of binder samples used blast furnace slag Novolipetsk Metallurgical Plant. The chemical composition is presented in table 1.

To mix the binder, an alkaline activator solution with a density of 1135 kg / m ^{3 was used} . Volcanic ash is a natural mineral raw material of the Mashuk fault, a deposit near the city of Pyatigorsk. The chemical composition is presented in table 1.

Samples for testing were prepared as follows. The binder was closed with an aqueous solution of an alkaline hardening activator, the ratio of the components corresponded to claim 1 and claim 2 of the claimed invention.

Samples were made from dough of normal density in accordance with the requirements of GOST 310.3-76. The strength of the slag-alkali binder samples was determined after heat-moisture treatment according to the 3 + 6 + 3 mode at an isothermal heating temperature of 95 + 5 ° С. The results of physical and mechanical tests are presented in table.2.

The introduction of a complex consisting of NaOH or soda ash and liquid soluble glass is aimed at increasing the strength of the cinder alkali binder under compression. This is achieved by the fact that glass of volcanic ash contains from 20 to 30% Al ₃ O ₃ , which leads to favorable conditions for the interaction of NaOH or soda ash and soluble liquid glass with slag and the formation of low-base hydroaluminosilicates, which leads to the compaction of cement stone, pore colmatization and increase in strength both in the initial stages of hardening and at 28 days of age.

And also the technical result is to slow down the setting time of the slag-alkali binder at the initial stage of hardening due to the selective action of the newly introduced components: technical modified lignosulfonate (LST-M) and alkaline hardening activator. The test results are presented in table.3.

The introduction of LST-M is aimed at regulating the timing of the setting of the slag-alkali binder test in the early stages of hardening. Slowing down the setting time of the binder consists in hindering the free access of the alkaline hardening activator to the active centers of the slag due to physical and mechanical adsorption of LST-M and volcanic ash on the surface of the slag.

The adjustment of the binder setting time is achieved by the fact that in the claimed object of the invention, volcanic ash of 1.92-9.09% by weight of the binder and technical modified lignosulfonate in the amount of 0.2-1.5% are used as a modifying additive by weight of slag and volcanic ash in terms of solids.

The setting time was determined according to GOST 310.3-76 from the test of normal density with a ratio of components of alkaline activator: soda ash 25-75; liquid soluble glass 25-75. The test results are presented in table.4.

As can be seen from table 4, the use of LST-M as an additive to cinder-alkaline binders in specified ratios allows, in comparison with the prototype, to slow down the start time of setting from 11 minutes to 143 minutes and the end of setting from 98 minutes to 491 minutes, which makes it possible to prepare a concrete mixture , transport to the place of concreting, lay it in the formwork and compact, without violating the continuity of the concrete mixture.

The manufacturing process of slag-alkali binder “GRAUND-M” consists in drying the starting components to a moisture content of 0.5-1%, dosing the components and grinding the granulated slag in a dry way to obtain a fraction with a specific surface of 2600-5000 cm ² / g. The proposed method is implemented, for example, as follows: volcanic ash and gravel slag are fed, for example, by belt conveyors to horizontal type drying drums (jasko@jasko.ru) or in an air-fountain dryer (poceydon@mail.ru). After passing through the drying process, the ingredients are cooled (“New in the preparation of sand for dry building mixtures. Rotating cooler drums”, spline3d@yandex.ru), volcanic ash and granulated slag have an output temperature of 20-85 ° C and a humidity of 0.5-1 , 0%. Binder ingredients: granulated slag, volcanic ash and technical modified lignosulfonate (LST-M) are dosed with a plate feeder ("Belleville feeders", mail@apmech.ru) in predetermined proportions and averaged in a continuous screw mixer with inclined screws ("Screw mixers", info@agro-mash.ru). The resulting mixture is stirred and then crushed in a centrifugal-impact mill ("The use of centrifugal-impact mills" MC "when grinding cement", V.N. Kushka, A.V. Artamonov, M.S. Garkavi, E.A. Ashurkova, E.E. Bundina, info@uralomega.ru).

Particles of material are crushed due to free impact on armored plates, and to a lesser extent abrasion occurs due to mutual collision of particles in the air stream when they move in the mill accelerator and from the accelerator to the armor plate. The combination of such effects on the source material leads to the production of binder particles of a strictly uniform shape, which prevents their aggregation and increases the reactivity of the material. The centrifugal impact mill classifier divides the obtained substance into fractions from 0 μm to 40 μm and from 40 μm to 80 μm, followed by mixing in a given proportion, which allows to obtain an astringent of various activity (Table 5 and Table 6).

The specific level of wear of the materials of a centrifugal impact mill (particle accelerator, breaker plates) is 0.15 kg / t, and the materials of a ball mill (grinding bodies, armor plates) are 1.1 kg / t. A lower level of wear of a centrifugal impact mill is associated with a different grinding method, as well as the absence of large rubbing surfaces, which helps to reduce metal losses in the grinding complex.

The presence of an air classifier in the centrifugal-shock complex system allows eliminating the process of material regrinding due to the continuous process of selecting grinding products from the working grinding system and returning to the working zone particles with a grinding coarseness greater than that specified in the classifier program. Such a system allows reducing energy costs for grinding materials compared to grinding in a ball mill for passage from 15 to 40%.

Combined grinding of gravel slag, volcanic ash and LST-M contributes to the production of a binder capable of maintaining a high binder reactivity for a long time. With this technology, uniform distribution of particles of volcanic ash on the grains of ground granulated slag occurs, and LST-M on the surface of volcanic ash causes dusting of slag particles and reduces the likelihood of contact of active centers with water in the air.

The introduction of LST-M is also aimed at reducing vysolobrazovaniya on the surface of concrete and mortars based on slag-alkali binder. Reducing efflorescence on the surface of concrete and mortars is caused by the process of binding excessive NaOH or soda, the difficulty of free migration to the surface of the concrete due to newly introduced components.

For testing, the samples were made from a test of normal density in accordance with the requirements of GOST 310.3-76 and placed after three days of curing in a desiccator over water. The binder samples made according to the prototype were coated on the spot in a day, and after 14 days on the surface of the samples, the soda efflorescence layer was 1-2.5 mm thick. The introduction of LST-M in an amount of 0.2% by weight of a binder in terms of solids helps to reduce the salt formation. A thin film on the surface of samples of normal hardening appears on the 23rd day from the date of manufacture of the samples. When dosing LST-M in an amount of 1.5% by weight of slag in terms of solids, no efflorescence on the surface of concrete samples is available.

The technical result is achieved by the fact that technical modified lignosulfonate (LST-M) in an amount of 0.2-1.5% by weight of slag in terms of solids contains organic compounds. These organomineral compounds bind the excess alkali into sedentary forms and thereby prevent its migration to the surface of concrete or mortar.

The properties of the proposed binder obtained by grinding in a ball and centrifugal impact mills are shown in table 5 and table 6.

Joint grinding in a mill of granular slag, volcanic ash, LST-M and a selected range of ratios of ingredients allows to increase the binder strength by 7.2-156% at the initial stage of hardening under normal conditions, and also after TVO by 36.6- compared to the prototype one hundred%.

The novelty of the declared binder “Ground-M” and the method for its preparation are that the setting time of the slag-alkali binder is regulated, the formation of salts is significantly reduced due to the introduction of LST-M and volcanic ash and the corresponding percentage of ingredients of the introduced components, the increase in the strength of the binder due to the proposed technological the process of obtaining the binder "Ground-M".

Experimental studies confirm the claimed properties. The claimed substance and the method for its preparation can be implemented on the basis of equipment mastered and manufactured by the industry.

The claimed binder "Ground-M" and the method for its preparation does not follow in an obvious way from existing technical solutions, scientific, technical and patent literature.

table 2 Physico-mechanical properties of the binder No. p.p. Ingredients Composition, wt.% Compression strength, MPa at the age of 28 days 1. Prototype Ground granulated slag 92.30 88.40 Condensed silica fume 4.60 Soda ash 3.10 2. Suggested Ground granulated slag 88.58 122,42 Volcanic ash 6.50 Alkaline activator 4.92 LST-M * 0.40 3. Suggested Ground granulated slag 85.23 167.11 Volcanic ash 7.50 Alkaline activator 7.27 LST-M * 0.80 4. Suggested Ground granulated slag 94.20 115.03 Volcanic ash 1.92 Alkaline activator 3.88 LST-M * 1,50 Note*. The dosage of fatty slag is made from the consumption of ground granulated slag and volcanic ash in terms of dry matter (in excess of 100%)

Table 6 The influence of the method of grinding granulated slag on the physico-mechanical properties of the slag alkali binder The name of indicators Type of mill centrifugal shock ball The fineness of the grinding residue on a sieve No. 008,% 0.02 12.70 Specific surface cm ² / g 3380 3470 Normal density,% 28 25 Setting time for slag-alkali test, hour-min Start 1-05 0-20 end 1-50 0-55 R / W solution 0.28 0.31 Diameter of a spread of a standard cone, mm 110 118 Tensile strength, MPa 3 days when bending 5.45 3.80 under compression 31.62 20.22 28 days when bending 8.70 6.00 under compression 80,10 65.5

Claims (2)

1. A method of producing a slag-alkali binder, including dehydration of volcanic ash and granulated blast furnace or electrothermophosphoric slag in horizontal type drying drums or pneumatic transport dryers at a temperature of 150-250 ° C, cooling in refrigerators to a temperature of 20-85 ° C, dosing of said slag and ash and Technical modified lignosulfonate - LST-M with averaging the composition in a continuous screw mixer, grinding the resulting mixture in a centrifugal impact mill to fr stocks of 0-80 microns and a specific surface of 2800-5000 cm ² / g with a return to this of a fraction of more than 80 microns separated in a continuous continuous air classifier and subsequent mixing with an alkaline activator of the composition, wt.%: 20-25% aqueous solution sodium hydroxide NaOH or soda ash 20-75, water glass with a density of 1.15-1.26 g / cm ³ 25-75, in the following ratio, wt.%:
Specified Slag 81.80-94.20 Alkaline activator (dry matter) 3.85-7.27 Volcanic ash 1.92-9.09 LST-M (dry matter) 0.2-1.5% by weight of the specified slag and ash (over 100%) 2. Slag alkaline binder, characterized in that it is obtained by the method according to claim 1.