Method to prepare concrete mix
SUBSTANCE: method to prepare concrete mix includes double-stage mixing of a binder, fillers, a superplasticiser and tempering water, at the first stage they first mix the binder, fine filler, 70-80% of coarse filler and 75-85% of tempering water to produce a homogeneous mix, then at the second stage to the previously mixed mixtyre they add the remaining part of the coarse filler, superplasticiser with remaining part of the tempering water, and finally all components are mixed to produce a homogeneous concrete mix of required workability. The superplasticiser is additive of Cemaktiv SU-1.
EFFECT: reduced consumption of superplasticiser and provision of the possibility to reduce duration of heat and moisture treatment of concrete.
2 cl, 1 tbl
The invention relates to the technology of preparation of mixes, including concrete mixes with superplasticizer for the production of precast concrete and reinforced concrete products and structures.
Known three-stage process of preparation of a concrete mixture according to the patent RU 2361848 C2, C04B 40/00, publ. 20.07.2009, the Method includes a preliminary mechanochemical activation of the mixing water with the addition nitrotitan-alkaline water and mechanochemical activation of the pulp, containing 60-70% pre-activated water, followed by mixing with the aggregates and the remainder of the activated water. The method allows for a 20% reduction in the amount of cement to improve the workability and the compressive strength and the tensile strength.
There is also known a method of preparing a concrete mixture according to the patent RU 1760981 A3, C04B 40/00, published 07.09.1992 G. In accordance with this method first mix in a turbulent high-speed mixer (600-700 rpm) water with high-level overdispersed silica fume with a specific surface area (20...40)·103cm2/g, was then added quartz sand, and then adding the cement, then the complex additive comprising a superplasticizer MF-DFA and nitrate of sodium or calcium. Final mixing is carried out in a slow speed mixer (40-60 rpm). Method providing�et increase concrete strength by 25 to 40% and reduce the consumption of cement for a given strength of up to 40%.
The closest to the proposed method is a method of preparation of the concrete mix according to the patent RU 2443650 C1, C04B 28/00, B28C 5/00, C04B 111/20, publ. 27.02.2012.
The method comprising mixing cement, aggregates, a superplasticizer and mixing water, is that pre-factory-mixed cement, aggregates and part of the mixing water to obtain a concrete mixture with a slump of 2-4 cm, then the resulting mixture is transported in a truck mixer to the place of use and not later than two hours after cooking add the aqueous solution of superplasticizer with the remaining calculated quantity of mixing water, and the concrete mixture is finally stirred for at least three minutes. The technical result achieved - increase workability, maintaining mobility of the concrete mix without reducing the strength of concrete. The method is designed mainly for monolithic construction. The best results this method provides for the introduction of superplasticizer in the concrete mixture 1 hour after pre-mixing.
However, it is perfectly acceptable in terms of monolithic construction, but are unsuitable for industrial technology of production of precast concrete and reinforced concrete, since such lengthening of the mixing cycle snige�camping equipment performance and turnover forms.
In addition, the method requires high consumption of the super expensive and does not provide the possibility of reducing the duration of moist curing (steam curing).
The object of the invention is to reduce the consumption of superplasticizer and providing the possibility of reducing the duration of moist curing of concrete.
The invention consists in that in the method of making a concrete mix, comprising two-stage mixing of binder, aggregates, a superplasticizer and mixing water, the first stage of the pre-mixed binder, fine aggregate, 70-80% coarse aggregate and 75-85% of the mixing water to obtain a homogeneous mixture, then in the second stage to a premixed mixture add the remaining coarse aggregate, superplasticizer with the rest of the mixing water and finally mix all the components until a homogeneous concrete mixture of the desired workability.
As a superplasticizer additive is applied to Chemactive SU-1.
Effect: reduced consumption of superplasticizer and reduction in the duration of moist curing of concrete by the proposed method can be explained by the fact that, when introduced into the concrete mixture of superplasticizer known methods of PR�comes intense adsorption of superplasticizer superfine particles of the starting components of the mixture and tumors, resulting in the concentration of surfactant additives in the liquid phase is significantly reduced, decreasing its plasticizing effect and strengthens the processes of flocculation hydratious binder. While slowing the growth of the primary structural strength of concrete, hence the need to increase the duration of moist curing to avoid the existence of destructive processes in the hardening concrete.
Proposed method of preparation of the concrete mix reduces the adsorption of superplasticizer, which is introduced at the final stage of mixing. Furthermore, the introduction of parts of coarse aggregate in pre-mixed mixture has delocalise action which accelerates the process of structure formation of cement stone before curing. This creates favorable conditions for shortening the overall length of TVO.
Originally stirred to obtain a homogeneous mixture of binder, fine aggregate, 70-80% coarse aggregate and 75-85% of the mixing water. Then in pre-mixed mixture was added the remaining coarse aggregate and superplasticizer with the rest of the mixing water and finally the mixture was stirred to obtain a homogeneous concrete mixture required �democracyfest.
As a superplasticizer can be used neutralized condensation products of naphthalene sulfonic acid and formaldehyde (the main component of superplasticizers grades p-3 on THE 6-14-625-80 and C-4 on THE 14-6-188-81), a condensation product of melamine with formaldehyde, hydrogen sulphite or sulfanilate sodium (superplasticizers 10-03 beyond 44-3-505-81 and MT-AR TU 6-05-1926-82), the neutralized condensation product of a sulfonated aromatic carbohydrates gasoil fractions of 200-400°C for catalytic cracking or pyrolysis oil with formaldehyde (superplasticizer 40-03 beyond 38-402-58-82), sulfonated phenol-formaldehyde oligomers (superplasticizer FO-SA TU 44-3-720-84), the neutralized condensation products carbocyclic and heterocyclic sulfonic acids with formaldehyde (superplasticizer N-1 on THE 44-3-639-83), esters of polycarboxylates and polyacrylates (Mobet grade 2 beyond 2600-003-54575429-2008, Dolit-PAC TU 5745-01-96326574-08, additives Sika® ViscoCrete® 20 HESika® ViscoCrete® 5 New on THE 2493-009-13613997-2011).
In the proposed method uses the superplasticizer Chemactive SU-1, TU-5745-001-96722436-2006. Chemactive SU-1 is a superplasticizer, with the effect of accelerating the hardening and slow the setting time, reduces the protective properties of concrete in relation to the valve. Applicable for commercial concrete.
The present invention is illustrated by the following �the reamer.
As an initial take a mixture of concrete production concrete mix design class B22,5 on the basis of:
- Portland cement 500 D0-N GOST 10178-85 production Sebryakovcement;
- Aksai river sand bucket don river with a fineness modulus of 1,57 that meets the requirements of GOST 8736-93;
- gravel fraction 5-20 mm of dense limestone Zhirnovsky Deposit that meets the requirements of GOST 8267-93, with the ratio of components (wt.h.):
cement: sand: gravel=1:1,76:3,64.
In conventional single-stage method of mixing cement consumption is 310 kg/m3, mixing water - 204 l/m3. Water-cement ratio W/C=0,66 ensures the workability of concrete mixture, characterized by the draft standard cone OK=1-2 cm.
Concrete mix, when similar to original mixture ratio, with the addition of the superplasticizer Chemactive SU-1 for THE 5745-001-96722436-2006 prepared by the proposed method and the prototype.
In all cases, the expense adjustment total flow rate of the mixing water and water-cement ratio shall be equitably compare mobility concrete mixtures.
From the prepared concrete mixtures is molded samples-cubes with edges of length 100 mm, which after a two-hour pre-exposure were subjected to heat and moisture treatment in laboratory steaming� camera with isothermal heating at 90°C.
Samples were subjected to strength tests established method immediately after curing and after 28 days of hardening under normal conditions.
The test results are shown in the table.
As can be seen from the above example, the proposed method (experiments Nos. 2, 3, 4) allows at least 25% to reduce the consumption of expensive of superplasticizer, and at least 20% reduction in the total duration of steam curing of concrete without reducing the strength compared with the closest analogue.
1. Method of preparation of concrete mixtures, comprising two-stage mixing of binder, aggregates, a superplasticizer and mixing water, characterized in that the first stage is mixed binder, fine aggregate, 70-80% coarse aggregate and 75-85% of the mixing water, then to this mixture was added the remaining 20-30% coarse aggregate, superplasticizer and the rest of the mixing water, and then finally the mixture was stirred to obtain a homogeneous concrete mixture of the desired workability.
2. A method according to claim 1, characterized in that the use of superplasticizer additive Chemactive SU-1.
SUBSTANCE: in the method to prepare a haydite concrete mix, including preparation and mixing of mixture components, mixing of the haydite concrete mix is carried out in a turbulent concrete mixer with rotor rotation frequency of at least 8 sec-1 and not more than 30 sec-1, at first 30% of required tempering water is supplied into the turbulent concrete mixer, and gradually haydite gravel is loaded with the running turbulent mixer, and mixed for 120 sec., then the required balance of water is supplied to the continuously running turbulent concrete mixer with addition of technical modified lignosulphonates and a gas forming additive PAK-3, then fly ash and cement are loaded, and the mix is mixed for 2-3 min. to produce homogeneous mix with required cone slump, at the following ratio of components, wt %: portland cement 20.00, haydite 41.50, superplasticiser LSTM 0.0312, fly ash of TPP 17.50, PAK-3 0.025, water - balance.
EFFECT: reduced process operations in production of haydite mix, increased frost resistance, heat insulation properties and reduced average density of haydite without strength reduction.
SUBSTANCE: method to manufacture construction products from foam concrete includes preparation of a foam concrete mix from portland cement, fractionated quartz sand, a foaming agent and water in a turbulent mixer, loading of the produced mix into moulds from dielectric material, on the side surfaces of which there are metal electrodes, exposure of the foam concrete mix to the AC electric field of specified frequency and intensity. Processing of the freshly moulded products with electric field is carried out at the field intensity of 1.5-4.5 V/cm for 0.5-5 min. Efficiency of foam concrete mix exposure to the AC electric field depends on grain-size composition of quartz sand and is maximum when sand fractions of 0.16-0.315 mm are used.
EFFECT: improvement of strength characteristics of foam concrete.
3 cl, 6 tbl
SUBSTANCE: method for obtaining a heat-insulating material involves mixing of filler and a binding agent with further shaping and hardening. Industrial wood chips 5±2 mm thick are used as filler, and rigid polyurethane foam consisting of polyol and isocyanate is used as the binding agent. First, components of the binding agent are mixed; then, the binding agent is mixed with the filler by layer-by-layer laying of a binding agent layer, a filler layer and a binding agent layer into a mould at the following component ratio, wt %: polyol 24-22, isocyanate 36-33, industrial chips 40-45. After supply of the components is completed, the mould is fixed with latches and exposed during 15-20 minutes.
EFFECT: reduction of density and thermal conductivity of material.
1 tbl, 1 dwg
FIELD: process engineering.
SUBSTANCE: invention relates to production of foam materials on the basis of asbestos, basalt, carbon, polyether or polyamide or any other inorganic and organic fibres to be used in aircraft and ship building, machine building, etc. This method comprises the steps that follow. Production of foam bilk from initial mix of fibres and feed of said foam bulk to conveyor belt. Foam bulk is dried in drying chambers at stepwise increase in temperature in successive zones. Foam bulk is annealed in the kiln to foam material and cut reset-size boards. Note here that drying and annealing comprises simultaneous effects of IR radiation and convective heat. Note here that drying stepwise temperature increase occurs at 60°C-170°C. Annealing is performed at 190-280°C. Foam bulk is fed through drying chambers and annealing kiln at the rate of 6-12 m/h. Invention proposes also the conveyor line to this end.
EFFECT: accelerated drying, higher quality of foam material, continuous production.
8 cl, 3 dwg
SUBSTANCE: invention relates to preparation of construction mixtures, primarily fine-grained concrete mixtures and mortars which harden in natural conditions or under steam curing. Disclosed is a two-step method of preparing a construction mixture using mineral filler, a plasticising additive, sand and binder. The first step comprises mixing the binder - portland cement M500 D20, mineral filler - silicon carbonate gaize, 55-65% sand and 60-70% hardening water to obtain a homogeneous mixture, and the second step comprises adding to the obtained mixture the remaining sand, plasticising additive - superplasticiser SP-1 and the remaining water, and finally mixing to obtain a homogeneous mixture of given workability.
EFFECT: reducing consumption of expensive materials without reducing strength of the obtained material.
SUBSTANCE: method comprises electrochemical treatment of mains water in three-chamber electrolysis unit with ion-selective membranes by alternating asymmetric current. Meanwhile the electrolysis unit anode is made from shungite. During the electrochemical treatment of water in the anode and in the anode chamber the ultrasonic oscillations are exited, the frequency of which exceeds the cavitation threshold frequency within a range from 20 kHz up to 100 kHz, and the intensity of the named ultrasonics is in the field of stable cavitation from 1.5 W/cm2 up to 2,5 W/cm2. Water treatment is stopped at achieving of density of particles of hydrated fullerene 10-3-10-4%.
EFFECT: improvement of frost resistance of concrete mix, increase of cement hydratation level and strength of cement stone in early periods of curing.
SUBSTANCE: method of activation of concrete mixing water by its modifying with carbon fulleroid nano-particles with its consecutive ultrasonic processing comprises the placement of shungite into a vessel with water, the mass of shungite amount no less than 1% of water mass, and ultrasonic oscillations are excited in water with the frequency in the range from 20 kHz to 100 kHz, from 1.5 W/cm2 up to 2.5 W / cm2, and 10-3-10-5% and water and shungite are subjected to named ultrasonic oscillations within 5-10 minutes until achieving of density of fullerene, emanated from shungite into activated water, then the activated water is passed through the filter and is used as a concrete mixing liquid, and the shungite bottoms are left in the vessel, which is filled with the next portion of water and the procedure of concrete mixing liquid activation is repeated.
EFFECT: improvement of physic-mechanical characteristics of concrete, decrease of water consumption or cement consumption without affecting the concrete strength.
1 ex, 1 tbl
SUBSTANCE: invention relates to methods of activating hardening water of cement-based composites. The method of activating hardening water of cement-based composites includes treating tap water in a plasmatron with low-temperature nonequilibrium plasma in a period of time ranging from 1·10-2 s to 5·10-2 s.
EFFECT: high efficiency and degree of activation of water in order to speed up hydration and strength gain in the early stage of concrete hardening.
FIELD: process engineering.
SUBSTANCE: invention relates to production of inorganic heat-resistant rustproof composites in production of plastics, antirust and lubing materials for construction, electrical engineering, etc. Proposed method comprises mixing of inorganic natural material, liquid glass, dolomite powder and additive, mix forming and thermal treatment. Used is liquid sodium glass, its density making 1.28-1.42 kg/m3, as inorganic natural material, that is, montmorillonite modified by organic substance. Said additive represents a hydrated cellulose fibre shaped to 5.0-20.0 mm long staple impregnated with 30%-aqueous solution of iron, zinc, copper and aluminium sulphates taken in the ratio of 1.0:0.5:0.5:1.0 in flushing bath for 70-80 minutes. Then, said fibre is squeezed to moisture content of 60-65% and dried at 120-140°C to remove 95-98% of residual moisture. Components are mixed by mechanical activation for 8-10 minutes, mix being formed and annealed at temperature increase from 140°C to 1300°C for 30-40 minutes. Note here that montmorillonite is modified by the product of interaction between caprolactam or its oligomers with butyl stearate. Mix contains components in the following ratio in wt %: modified montmorillonite - 20-60, liquid glass - 20-30, dolomite - 10-35, cellulose fibre - 10-15. This invention is developed in dependent clauses.
EFFECT: higher fire resistance, lower heat conductivity factor, antirust properties.
3 cl, 3 ex, 1 tbl
SUBSTANCE: method of producing a composite material consists in the fact that a cavity of a casing construction is filled with very rigid concrete, produced by mechanic activation of a cement composition. The cement composition includes 30% of cement of grade PC-500DO-N, 7.5% of microsilica, 1.8% of an expanding additive EA-H, 20% of river washed sand with the fineness modulus Mf 5, 40% of basalt gravel with a size up to 30 mm, 0.7% of an ethylene glycol-based superplasticiser. Mechanic activation is carried out in blade mixers of a forced type with a frequency of blade rotation not less than 60 rpm for not less than 20 min. Highly-strong concrete is poured into the cavity of the casing construction, and is simultaneously consolidated by vibration processing. Then, to exclude steam discharge from it, the cavity of pouring is closed. Autoclave solidification of concrete, consisting in the fact that the entire construction is evenly heated to a temperature of nearly 200°C to solidify it, is realised. The construction is exposed to the said temperature for 12 hours. After that, it is gradually cooled to room temperature and kept at the said temperature until complete hydration of cement takes place. And, finally, mechanical processing of basic surfaces is realised.
EFFECT: simplification of technology of the material production.
FIELD: ceramic binder and ceramic materials made from the same.
SUBSTANCE: ceramic binder is obtained by thermal treatment of raw materials containing (mass %) clay (e.g., clay waste) 20-45; limestone (e.g., limestone waste) 5-30; and ash (e.g., ash from thermoelectric plant) 25-75, at 900-11500C. Method for production of ceramic materials using the claimed binder includes mixing of raw materials, forming, and thermal treatment at 174-2100C under pressure of 0.8-1.6 MN/m2 in saturated water steam.
EFFECT: low-cost ceramic materials with reduced volume weight and high mechanical strength.
2 cl, 3 ex, 3 tbl
FIELD: manufacture of building materials.
SUBSTANCE: quick-hardening bound cement mortar including, vol parts: cement 6-9, water 2-3, aqueous epoxide resin dispersion 1, and hardener 1, said cement being of quick-hardening type and said dispersion additionally containing polyurethane rubber. Quick-hardening cement can be alumina-based cement. In a method of preparing quick-hardening bound cement mortar including mixing cement with aqueous epoxide resin dispersion and hardener on a surface immediately before underwater application, one volume part of water is diluted with one volume part of hardener and stirred, after which one volume part of aqueous dispersion of epoxide resin and polyurethane rubber are added, resulting mixture is agitated and then, depending on particular application, 1 or 2 vol volumes of water are added and, after agitation, resulting composition is used to temper quick-hardening cement, and stirred in low-speed mixer until soft plasticine-type plastic homogenous mass is obtained, after which mortar is held up to 5 min and agitated once more. Escort method of repairing concrete and reinforced concrete underwater structures comprises conveying quick-hardening cement mortar into underwater repair operation zone and manually laying thus prepared mortar onto prepared surface with defective spots. Conveyance of mortar can be accomplished by means of containers or buckets, or yet by means of worm mortar pumps. Invention enables preparation of repair material characterized by dimensional stability, short setting time and fast hardness development, non-diffuseness in aqueous media, waterproofness, frost resistance, crack resistance, resistance to corrosive media (salt and alkali solutions, petroleum products), high adhesion to cement, concrete, and metallic surfaces, and not leading to corrosion of hardware.
EFFECT: improved performance characteristics of cement mortar.
FIELD: no-fines concrete production useful in drainage systems and curb construction building.
SUBSTANCE: claimed method includes mixture preparation containing of Portland cement, water and target additive in wing blender; blending of said mixture with dense coarse aggregate and subsequent laying of obtained concrete mixture. Said aggregate is charged into blender-capsulator, then mixture of Portland cement, water and target additives is fed, and cotreatment is carried out for 1-3 min. Claimed concrete mixture contains (mass %): Portland cement 5-15, said aggregate 82-88, target additive 0-1.0, and balance: water.
EFFECT: simplified technology of no-fines concrete; concrete of improved quality.
3 ex, 1 tbl
FIELD: manufacture of building materials.
SUBSTANCE: method consists in preliminarily affecting only tempering water directly in supply tank of concrete-mixing unit by means of high-voltage electric discharges emerging in interelectrode spaces of electrode system followed by adding chemical additives before mixing tempering water with binder and fillers, all operations being accompanied with active agitation of with mechanical agitator driven from electric motor.
EFFECT: considerably shortened total mixing time, improved quality of mix because of more evenly distributed activated water molecules and chemical additives, and reduced consumption of power on activation of water.
FIELD: manufacture of building materials.
SUBSTANCE: method consists in preliminarily affecting only tempering water directly in supply tank of concrete-mixing unit by means of high-voltage electric discharges emerging in interelectrode spaces of electrode system followed by adding chemical additives before mixing tempering water with binder and fillers, all operations being accompanied with active agitation by means of air bubbles bubbling through water, e.g. from gas collector with nozzles supplied with air from compressor.
EFFECT: considerably shortened mixing time, improved quality of mix, and reduced consumption of power on activation of water.
FIELD: manufacture of large-size cement-fiber plates used for facing buildings and making roof covering.
SUBSTANCE: method comprises steps of mixing cement, sand, micro-filler, reinforcing synthetic fibers, plasticizing additive and water; shaping and drying; using wollastonite as micro-filler. At first in turbulence mixer dry loose components such as cement, sand, wollastonite are mixed. Then reinforcing synthetic fibers are added and composition is mixed. Plasticizing additive and water are added at next relation of ingredients, mass.%: cement, 68 -81; sand, 9.5 -13.5; wollastonite, 9.25 - 12.50; synthetic reinforcing fibers, 0.16 -0.55; plasticizing additive, 0.38 -0.43; water, the balance. Articles are dried in air in natural condition. Polypropylene fibers are used as synthetic reinforcing fibers. Mixing of cement, sand and wollastonite in turbulence type mixer is realized during time period no more than 30 s at using water heated up to temperature no lower than 40°C. Size particle of wollastonite is in range 100 -170 micrometers.
EFFECT: enhanced quality of plates.
5 cl, 1 ex, 1 tbl
FIELD: building materials, particularly for forming heat insulated and structural heat insulated articles, for forming cast-in-place heat- and noise-insulation floor panel filling of cellular concrete.
SUBSTANCE: method involves preparing cellular concrete mix; pouring the mix into mold or formwork; applying additive on cellular concrete mix surface; treating the surface layer with device having rotary disc provided with needles variable in length and heat treating the concrete mix. Cellular concrete mix is prepared with the use of composite gas-foam pore former in tubular mixing means during cellular concrete mix heating up to 45-65°C. Additive is applied on convex concrete surface just after cellular concrete mix heaving. Fibrous agent and/or water-soluble component taken in amount of 2-8% of the cellular concrete mix weight is used as the additive. The surface layer has 2 cm thickness. Disc comprises needles gradually decreasing in length from disc center to periphery thereof. Fibrous agent is asbestos, wool, rock wool and polymeric fiber waste. Water-soluble polymer is polyvinyl acetate, polyvinylchloride, polysterene or polyacryl.
EFFECT: improved service characteristics of the ready article, reduced time of production due to optimal combination of above mix preparing and mechanical surface treatment operations.
3 cl, 1 tbl
SUBSTANCE: method comprises supplying water and cement or water, cement, and sand to the cavitation mixer, mixing the ingredients in the presence of an activator during 5-15 min, introducing the dry blowing mixture to the solution produced, and further mixing during 15-60 s. The dry blowing mixture is composed of, in mass %, 70 of cement, 12 of pigment aluminum powder, 12 of water-soluble aluminum powder, 2 of antifreeze plasticizer, and 4 of water.
EFFECT: reduced cost and enhanced efficiency.
FIELD: manufacture of building materials.
SUBSTANCE: invention relates to manufacture of polystyrene-concrete parts for use in construction as wall and heat-insulating material. Manufacture of heat-insulation products comprises preparation of molding mix from Portland cement (60.0-65.6%), water, and granulated foamed polystyrene with loose density 10-20 kg/m3 (2.2-4.4%), molding, and heat treatment of products. Invention resides in that molding mix additionally includes microsilica (6.6-12.0%) and superplasticizer S-3 (0.6-0.66), starting mix Portland cement/microsilica/foamed polystyrene is first stirred for 2-3 min, then water containing superplasticizer is added, resulting mix is stirred for further 3-5 min and loaded into molding boxes. Molding involves vibrocompaction and pressing followed by unloading of products from molding boxes and heat treatment: 2 h at 15-25°C, 8 h at 40-60°C, and 1 h at 15-30°C.
EFFECT: reduced consumption of cement, improved placeability and moldability of mix, increased strength of products, and increased productivity.
FIELD: construction industry.
SUBSTANCE: the invention is pertaining to the field of construction industry, in particular, to the production of glass containers, in particular, to the methods of production of an items out of a concrete mix, which may be used in municipal landscape improvement of overall decor accomplishment of the modern town-planning in the form of the decorative fencing, lawns, roads, gardens in front of buildings, flower beds, at paving of territories and in other cases of the landscape design. The technical result is production of the items with a high strength, life duration, frost-resistance, increased chemical durability, watertightness, cement saving due to substitution of its optimum amount for microsilica. The method of production of an item our of a concrete mixture provides for preparation of concrete mixture by stirring of cement, sand, an pigment of organic or inorganic generation, C-3 superplasticizer and water with the subsequent laying of the concrete mixture in the form with an relief insert, placing the form on a molding table, compaction by vibration. At that they use sand with the grade modulus of Mgr-2.4-3.2. The concrete mixture is added with microsilica, and components take in the following ratio (in mass %): cement - 19.5-22.0, the indicated sand - 69.0-69.2, the indicated pigment - 0.7-1.0, C-3 superplasticizer - 0.1-0.21, microsilica - 1.0 3.4, water - the rest. At that first they stir the indicated sand and the indicated pigment for 45-50 seconds, then this mixture is added with the cement and microsilica and again the mixture is stirred during 60-70 seconds, then it is added with water with C-3 superplasticizer and the mixture is stirred for 120- 180 seconds, and compaction by vibration is carried out for 1-2 seconds with the subsequent simultaneous compaction by vibrations and pressure of 10-15 atm during 6-15 seconds. After that the newly formed item is placed in the chamber of the hygrothermal treatment with the temperature 0f 17-23°C and the relative humidity of 90-100 % and keep there for 15-20 hours. At that the form is made out of a steel and the figure inserts are made out of polyurethane.
EFFECT: the invention ensures production of the items with a high strength, life duration, frost-resistance, increased chemical durability, watertightness, cement saving due to substitution of its optimum amount for microsilica.
2 cl, 3 tbl, 1 ex