RU2502690C1 - Granular nano-stucture-forming filler based on highly siliceous components for concrete mixture, composition of concrete mixture for obtaining concrete building products and concrete building product - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to industry of building materials and can be applied for obtaining concrete building products in industrial and civil construction. Granular nano-structure-forming filler based on highly siliceous components for concrete mixture, produced from silica-containing raw material, in form of granules with size 0.5-10 mm, which consist of core and formed on its surface protective coating from dry dust-like mixture of jointly milled quicklime and sodium silicofluoride with their weight ratio 0.85-0.95:0.05-0.15 with the following solidification to strength not less than 0.12 MPa, where core is obtained by granulation of silica-containing rock mixture, milled to passing through sieve with cell 0.315 mm, and swollen perlite sand with size of particles to 0.16 mm, in ratio 0.60-0.95:0.05-0.40 by weight, fastened by alkaline-containing binding agent, which consists of water solution of alkali metal hydroxide and Na silicate with density 1.2-1.3 g/cm³ (alkaline:silicate=0.85-0.95:0.05-0.15 by weight) in quantity 5-20% of mixture. Concrete mixture, which contains, wt %: said filler 20-50, cement 10-15, sand 25-50, water - the remaining part. Concrete building product, obtained from claimed mixture.

EFFECT: elimination of aggregation in the process of milling, reduction of density and heat-conductivity with increase and preservation of product strength, reduction of power consumption.

3 cl, 1 ex, 2 tbl

Description

The invention relates to the construction materials industry and can be used to obtain concrete building products in industrial and civil engineering.

Known granular aggregate to obtain a concrete mixture, consisting of a core and a protective shell. The core is made by granulation on a plate granulator of a mixture of dispersed silica-containing components - TPP ash (dispersion not less than 200 m ² / kg) and sludge from a biological wastewater treatment aeration station with a binder - ground lime (dispersion 500-600 m ² / kg) and gypsum ( with a brand of at least 100 and a dispersion of at least 350 m ² / kg) in the ratio of the components of the mixture, respectively, 0.3: 0.5: 0.15: 0.05 by weight. After granulation, a 3-5 mm thick protective coating is applied to the core by wetting the core of the granule with liquid glass and dusting or rolling it on a disk or drum granulator with a dry, dusty mixture of lime, gypsum and mineral dispersed filler (ash from a thermal power station, state district power station, loam, etc. ) in the ratio of the components of the mixture, respectively, 0.35: 0.10: 0.55 by weight. After the formation of the granules with the aim of curing, heat and moisture treatment is applied at a temperature of 90 ° C with isothermal exposure for one hour [RF patent No. 2077517, IPC 6 C04B 20/10, 1993].

The disadvantages of this granular aggregate are increased heat energy consumption for heat and moisture treatment in the manufacture of concrete products: first, granular aggregate is exposed to heat and moisture treatment, then a molded building product including the above aggregate, and the resulting concrete construction products subjected to heat and moisture treatment during hardening, have low water resistance, strength and heat-insulating ability.

A known method of manufacturing a granular aggregate for concrete, consisting of a core and a shell, comprising forming a core in the presence of liquid glass from a mixture of co-milled expanded perlite and sodium hydroxide, rolling the shell onto the core surface from co-milled quicklime with sodium silicofluoride, curing the granules in a microwave field with a specific energy consumption of 41-86 J / cm ³ [Pat. RF №2433975, IPC C04B 28/18, C04B 20/00, C04B 28/04, C04B 111/27].

The closest technical solution adopted as a prototype is a granular aggregate based on natural sedimentary high-siliceous rocks for concrete mix, consisting of a core and a shell, where the core is obtained by granulating a mixture of ground together to a specific surface of 150-250 m ² / kg of natural sedimentary high-siliceous rock and alkali metal hydroxide at a mass ratio of 0.70-0.95: 0.05-0.30 with a binder - an aqueous solution of sodium silicate with a density of 1.2-1.3 g / cm ³ in an amount of 0.1-7, 0% of the mixture, the formation of protection a melt shell on the surface of the core is produced in a dry, dusty mixture of coarsely ground quicklime and sodium silicofluoride with a mass ratio of 0.85-0.95: 0.05-0.15, followed by hardening to a strength of at least 0.12 MPa [ RF patent No. 2361834, IPC 6 C04B 28/04].

The disadvantage of the above inventions is the complexity of the formation of the core due to the fact that the joint grinding on the surface of the alkali metal hydroxide adsorbs moisture from the air and the subsequent reaction of the interaction of the components with the release of soluble silicates of alkali metals, entailing aggregation of the components, the termination of further grinding and a decrease in the activity of the finished product products when used in concrete products. Another disadvantage is the high density of aggregate, which does not allow to obtain lightweight concrete.

The present invention solves the problem of eliminating aggregation during grinding of aggregate components, as well as decreasing the density, subsequently of concrete products with a decrease in thermal conductivity while increasing and maintaining the strength characteristics of concrete building products subjected to heat and moisture treatment during hardening, and reducing energy consumption in the manufacture of concrete products due to reduction of energy consumption in the manufacture of aggregate.

The technical result of the claimed invention is achieved due to the fact that the core of the aggregate consists of a mixture of silica-containing component and expanded perlite sand in a ratio of 0.60-0.95: 0.05-0.40 by weight, bonded with an alkali-containing binder. At the same time, sedimentary rocks such as flask, tripoli, diatomite, perlite, previously crushed before passing on a 0.315 sieve, are used as a silica-containing component. The alkali-containing binder consists of an aqueous solution of alkali metal hydroxide and Na silicate with a density of 1.2-1.3 g / cm ³ (alkali metal hydroxide: silicate = 0.85-0.95: 0.05-0.15 by weight) in the amount of 5-20% of the mixture.

The selected dispersion size of the silica-containing component is due to a sufficient degree of refinement for the alkali metal hydroskide and amorphous silica, which is part of the rocks, to enter into the reaction.

To obtain granular aggregate cores, natural sedimentary siliceous rock, crushed before passing through a 0.315 mm sieve, was dosed with expanded perlite sand by the weight method. The resulting material was fed to a standard plate granulator, where, when spraying an aqueous solution of an alkali metal and liquid glass, core aggregates of a given size were obtained. The obtained core aggregates were directed to the formation of a protective shell by rolling into a drum mixer, which was also fed from a dry dusty mixture of coarsely ground quicklime and sodium silicofluoride Na ₂ SiF ₆ . The strength gain of the granular aggregate during its hardening at ambient temperature was controlled by testing in a cylinder according to GOST 9758-86.

Component Feature:

1. As a silica-containing component for the manufacture of the core aggregate used natural sedimentary siliceous rocks (the chemical composition of silica-containing raw materials is presented in table I):

- flask selected from the open pit of the Korkinsky deposit, Chelyabinsk region;

- a flask selected from the open pit of the Alekseevsky deposit, the Republic of Mordovia;

- Tripoli Fokinsky deposits, Bryansk region;

- diatomite of the Inza deposit. Ulyanovsk region.

2. Expanded perlite sand according to GOST 10832-91 was used as a light filler. Particle size up to 0.16 mm, M75 bulk density grade.

3. For the manufacture of a protective shell filler used:

- quicklime for construction GOST 9179-77;

- sodium silicofluoride Na ₂ SiF ₆ TU 6-09-1461-91;

- an aqueous solution of sodium silicate (water glass) TU 2385-001-54824507-2000.

4. Tap water in accordance with GOST 23732-79.

5. When granulating the powder with ground natural sedimentary high-siliceous rock with expanded perlite sand on a plate granulator, an aqueous solution of alkali metal hydroxide (Na, K) and sodium silicate (liquid glass according to TU 2385-001-54824507-2000 with a density of 1.2 -1.3 g / cm ³ ).

Table 1 The chemical composition of siliceous raw materials Silica raw materials The content of oxides, wt.% SiO ₂ AI ₂ O ₃ Fe ₂ O ₃ Cao MgO TiO ₂ R ₂ O SO ₃ p.p.p. Silicon hydroxide 99.98 - - - - - - - 0.02 Flask (R. Mordovia) 86.5 4.6 3.62 0.98 0.77 0.35 2.07 0.29 0.7 Diatomite (Ulyanovsk Region) 81.08 5.63 2.67 0.01 0.68 0.32 1.33 0.05 7.50 Expanded perlite (St. Oskol) 75.5 12.5 0.7 1,6 - - - - 9.7 Tripoli (Bryansk region) 74.20 7.20 2.40 6.60 1.10 - 0.60 - 8.60 Perlite (R. Buryatia) 74.00 14.00 2.60 2.10 - - 2,36 - 8.01

An example of a specific implementation.

Preparation of granular aggregate cores. Ground flask (9 kg) and expanded perlite sand (1 kg), i.e. in a ratio of 0.90: 0.10 by weight was simultaneously fed into a plate granulator. An aqueous solution of sodium hydroxide and sodium silicate in an amount of 7% was applied to the surface of the powder by spraying with respect to the weight of the core aggregate. The rotation speed and the angle of inclination of the granulator plate were controlled by the diameter of the obtained cores, which in this case was 4.0-4.5 mm.

Obtaining a protective shell on the nuclei. The obtained cores were sent for dusting with a dry, dusty mixture of coarsely ground quicklime and sodium silicofluoride Na ₂ SiF ₆ (9 kg) to obtain granules with a shell thickness of 0.2-0.5 mm. Dusting was carried out in a drum mixer.

Part of the obtained granular material after storage for 10 hours at ambient temperature was tested for strength by compression in a cylinder according to GOST 9758-86 (2003), the strength was 0.25 MPa.

A concrete mixture based on the inventive granular nanostructured aggregate is intended for the manufacture of concrete building products, namely structural heat-insulating materials, and includes the inventive aggregate, cement, sand and water in the following ratio, wt.%:

aggregate 20-50 cement 10-15 sand 25-50 water 10-15

The preparation of the concrete mixture, the molding of samples and their heat and moisture treatment were carried out according to the known method [Gershberg O.A. Technology of concrete and reinforced concrete products. - M .: Stroyizdat, 1971, pp. 98-102, 305-313]: the components were dosed in a gravimetric manner: Portland cement, quartz sand and granular aggregate were mixed in a gravity mixer until homogeneous and water was added. Samples were formed in the traditional way by filling in standard forms 2FK-100 according to GOST 10181-2000. The exposure time in the forms is 6 hours. Heat and moisture treatment of concrete samples was carried out in a steaming chamber at atmospheric pressure according to a 2 + 6 + 2 mode and an isothermal holding temperature of 90 ° C.

To compare the properties of building products, based on the inventive concrete mixture, the mixture ratios were chosen equal to the median of the declared interval (table 2), the ratio of components, wt.%:

aggregate 35 cement 16.25 sand 37.5 water 16.25.

Introduction to the composition of the concrete mixture of the inventive granular aggregate of 0.5-10 mm in size, consisting of a core in the form of interconnected alkali metal hydroxide solution and liquid glass of ground natural sedimentary high-siliceous rock, which is coated with a dry dusty mixture of coarsely ground quicklime and sodium silicofluoride Na ₂ SiF ₆ , allows to obtain durable concrete building products with reduced thermal conductivity and water permeability, while eliminating steaming aggregate significantly reduced the energy intensity of the obtained wall products.

Replacing part of the silica rock in the core of the aggregate with expanded perlite helps to reduce thermal conductivity while increasing the permeability of concrete products. The addition of 1% to 4% by weight of expanded perlite leads to an uneven distribution over the volume, as a result of which the pores have an disordered structure. The same phenomenon is observed when more than 40% expanded perlite is added.

The optimal ratio in the core is 60-95% by weight of silica sedimentary rock and 5-40% expanded perlite.

With an optimal ratio of components (composition No. 3 of Table 2), the resulting concrete building products have the following advantages compared to the known ones:

1) the thermal conductivity increases by 20-40%, while the brand for water resistance remains equal to the prototype;

2) the inventive granular composite aggregate does not require autoclaving before entering it into the concrete mix, due to this, energy consumption is reduced when receiving building products.

In the process of applying a protective shell from a dry pulverized mixture of coarsely ground quicklime and sodium silicofluoride Na ₂ SiF ₆ onto the core of the aggregate, the components of the shell interact with liquid glass, which leads to a rapid increase in the strength of the granules of the composite aggregate at ambient temperature, which allows it to be used in the preparation concrete mixtures without additional energy-intensive heat and moisture curing. In the process of moisture and moisture treatment of the claimed concrete building products in the cores of a granular aggregate, water-soluble sodium silicates are synthesized, which, penetrating through the protective shell, provide extremely strong adhesion of the claimed granules with the concrete matrix of the product.

Granular aggregate according to the prototype, when introduced into the composition of concrete building products during heat-moisture treatment, interact with the concrete matrix in volume, similar to the proposed aggregate. Products based on the prototype have the worst thermal conductivity with a slight increase in strength.

Obtained by the present method, concrete building products have improved adhesive properties with respect to plaster mortars.

Claims (3)

1. Granular nanostructured aggregate based on highly siliceous components for concrete mix, made of silica-containing raw materials, in the form of granules with a size of 0.5-10 mm, consisting of a core and a protective shell formed on its surface from a dry dusty mixture of ground powder of quicklime and sodium silicofluoride Na ₂ SiF ₆ at a weight ratio of 0.85-0.95: 0.05-0.15, followed by hardening to strength of at least 0.12 MPa, wherein the core is obtained by granulating a mixture of silica-containing species, and crushed before passing on a sieve with a mesh of 0.315 mm, and expanded perlite sand with a particle size of up to 0.16 mm, taken in a ratio of 0.60-0.95: 0.05-0.40 by weight, bonded with an alkali-containing binder, consisting of an aqueous solution of alkali metal hydroxide and Na silicate with a density of 1.2-1.3 g / cm ³ (alkali: silicate = 0.85-0.95: 0.05-0.15 by weight) in an amount of 5-20% of mixtures. 2. A concrete mixture based on granular nanostructured aggregate for the manufacture of building products, including aggregate according to claim 1, cement, sand and water in the following ratio, wt.%:
aggregate 20-50 cement 10-15 sand 25-50 water 10-15 3. Concrete construction product, characterized in that it is made from a mixture according to claim 2.