RU2518629C2 - Granulated nanostructuring filling agent based on highly silica components for concrete mixture, composition of concrete mixture for obtaining concrete construction products (versions) and concrete construction product - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to industry of construction materials and can be used for obtaining concrete construction products. Granulated nanostructuring filling agent based on highly silica components for concrete mixture, consisting of silica-containing raw material in form of granules with size 0.5-10 mm, which have core, bound by means of water solution of alkali-containing binding agent, and protective envelop, where core consists of highly silica rock, crushed until it passes sieve with 0.315 mm cell or swollen perlite sand with particle size to 0.16 mm, as binding agent used is water solution of hydroxide of alkali metal and sodium silicate, taken with ratio 0.6-0.99:0.01-0.4 by weight, in amount 5-30% of mixture, and protective envelop on core surface is formed by its granulation with dry Portland cement with further hardening to strength not lower than 0.12 MPa. Concrete mixture for manufacturing construction product in accordance to one version contains, wt %: Portland cement 15-25, sand 50-60, water 10-13, claimed filling agent 2-20; in accordance with the other version it contains, wt %: Portland cement 20-35, water 10-15, claimed filling agent 50-70. Concrete construction product, manufactured from said mixture by one or the other version.

EFFECT: reduction of density of filling agent and product, reduction of heat conductivity with preservation of strength.

4 cl, 2 tbl, 1 ex

Description

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

Known granular aggregate for concrete mix, 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 name 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 particulate 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 humidity treatment is applied at a temperature of 90 ° C with isothermal exposure for one hour [RF patent No. 2077517, IPC6 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 subjected to heat and moisture treatment, then a molded construction product including the aforementioned aggregate, as well as the resulting concrete construction products subjected to heat and moisture treatment during hardening, have low water resistance, strength and heat-insulating ability.

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 with 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 co-milled 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 disadvantages of the above inventions are the complexity of the formation of the core due to the fact that the joint grinding on the surface of an alkali metal hydroxide adsorbs moisture from the air and the subsequent reaction of the interaction of the components with the release of soluble alkali metal silicates, entailing the aggregation of the components and the termination of further grinding, and therefore decreased activity of the finished product when used in concrete products, in addition to this, the disadvantage is the high density of the aggregate, not allowing to obtain light concrete, while the shell of lime has a weak contact zone with the cement matrix, resulting in additional porosity.

The present invention solves the problem of eliminating aggregation during grinding of aggregate components, reducing its density, and subsequently the density of concrete products, resulting in reduced thermal conductivity, while maintaining or increasing the strength characteristics of concrete building products, reducing energy consumption, since the application of the invention does not require roasting. Using dry Portland cement as a filler for a filler solves the problem of the occurrence of additional porosity and a weak contact zone of a granular nanostructured filler and cement matrix.

The technical result of the claimed invention is achieved due to the fact that the granular nanostructured aggregate based on high-siliceous components for concrete mix consists of silica-containing raw materials in the form of granules with a size of 0.5-10 mm, having a core bonded with an aqueous solution of alkali-containing binder, and a protective shell. The core consists of high-siliceous rock, crushed before passing on a sieve with a mesh of 0.315 mm or expanded perlite sand with a particle size of up to 0.16 mm, an aqueous solution of alkali metal hydroxide and sodium silicate, taken in a ratio of 0.6-0, is used as a binder 99: 0.01-0.4 by weight, in an amount of 5-30% of the mixture, and the protective shell on the surface of the core is formed by rolling it with dry Portland cement, followed by hardening to a strength of at least 0.12 MPa.

To obtain granular aggregate cores, natural sedimentary silica rock, crushed before passing through a 0.315 mm sieve, or expanded perlite sand with a particle size of up to 0.16 mm, was fed to a standard plate granulator, where a filler core of a given size was obtained by spraying an aqueous alkali metal solution and liquid glass. The obtained core aggregates were sent to a drum mixer to form a protective shell by pouring with dry Portland cement a grade of at least CEM II 32.5 according to GOST 31108-2003, followed by hardening to a strength of at least 0.12 MPa. The strength gain control of the granular aggregate during its hardening at ambient temperature by testing in a cylinder was carried out according to GOST 9758-86.

Characteristics of the components.

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

- 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 Inzensky deposit, Ulyanovsk region;

- expanded perlite sand according to GOST 10832-91, particle size up to 0.16 mm, grade for bulk density M75.

Table 1 The chemical composition of siliceous raw materials Silica raw materials The content of oxides, wt.% SiO ₂ Al 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

2. For the manufacture of a protective cover for the aggregate, Portland cement CEM I 42.5 H GOST 31108-2003 was used;

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

4. Sodium hydroxide (technical sodium hydroxide) GOST 2263-79

5. Sodium silicate (water glass) according to TU 2385-001-54824507-2000 with a density of 1.2-1.3 g / cm ³ .

Concrete example

Preparation of granular aggregate cores.

The crushed flask was fed into a plate granulator. On the surface of the powder by spraying was applied an aqueous solution of an alkali metal and sodium silicate with a density of 1.25 g / cm ³ in an amount of 7% relative to the mass 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 dry Portland cement of grade no lower than CEM II 32.5 to obtain granules with a size of 5.0 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 materials, and includes the inventive aggregate, Portland cement, sand and water in the following ratio, wt.%:

Portland cement 15-25 sand 50-65 water 10-13 aggregate 2-20

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 by weight: Portland cement, quartz sand and granular aggregate were mixed in a screw mixer until smooth 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.

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

Portland cement 20-35 water 10-15 aggregate 50-70

Preparation of concrete mix.

The components were dosed by the gravimetric method: Portland cement mixed with water and a pre-saturated granular aggregate were mixed in a gravity mixer until homogeneous.

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 the 3 + 6 + 3 mode and an isothermal holding temperature of 85 ° C. This is due to the increased resistance to heat transfer of the mixture due to the introduced granular aggregate of low density.

To compare the properties of building products based on the inventive concrete mixture, the ratios of the components of the composition of the granular nanostructural aggregate based on the flask of the Alekseevsky deposit (rep. Mordovia) equal to the median of the declared interval were selected (table 2).

Introduction to the composition of the concrete mixture of the inventive granular aggregate with a size of 0.5-10 mm, consisting of a core in the form of interconnected solution of alkali metal hydroxide and sodium silicate ground natural sedimentary high-siliceous rock, which is covered with a shell of dry portland cement, allows you to get durable concrete building products with reduced thermal conductivity and water permeability, while due to the exclusion of steaming aggregate significantly reduces the energy intensity of the obtained wall products.

With an optimal ratio of components (composition No. 2, Table 2), the obtained structural and heat-insulating concrete building products have the following advantages compared to the known ones:

1) strength indicators increase by 15%, the brand for water resistance increases to B10;

2) the inventive granular composite aggregate does not require autoclaving before entering it into the concrete mix, thereby reducing energy consumption when receiving building products.

With an optimal ratio of components (composition No. 4, Table 2), the obtained heat-insulating concrete building products have the following advantages compared to the known ones:

1) the thermal conductivity is reduced by 70%;

2) the inventive granular composite aggregate does not require autoclave processing to obtain heat-insulating concrete, due to this, energy consumption is reduced when receiving building products.

In the process of applying a protective shell of dry Portland cement to the core of the aggregate, the interaction of the shell components with liquid glass occurs, 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 of concrete mixtures without additional energy-intensive heat and moisture curing. In the process of moisture and moisture treatment of the inventive 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 inventive granules to the concrete matrix of the product, and in the case of heat-insulating concrete - adhesion of the aggregate particles themselves.

The granular aggregate according to the prototype, when introduced into the composition of concrete building products during heat-moisture treatment, interacts 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, aggregate and concrete products solve the problem of eliminating aggregation during grinding of aggregate components, reducing its density, and subsequently the density of concrete products, resulting in reduced heat conductivity, while maintaining or increasing the strength characteristics of concrete building products, reducing energy consumption, so as when applying the invention does not require firing. Using dry Portland cement as a filler for a filler solves the problem of the occurrence of additional porosity and a weak contact zone of a granular nanostructured aggregate and cement matrix.

Claims (4)

1. A granular nanostructured aggregate based on highly siliceous components for a concrete mixture, consisting of silica-containing raw materials in the form of granules with a size of 0.5-10 mm, having a core bonded with an aqueous solution of alkali-containing binder, and a protective shell, characterized in that the core consists of highly siliceous rock crushed before passing on a sieve with a mesh of 0.315 mm or expanded perlite sand with a particle size of up to 0.16 mm, an alkaline metal hydroxide aqueous solution is used as a binder and sodium silicate, taken in a ratio of 0.6-0.99: 0.01-0.4 by weight, in an amount of 5-30% of the mixture, and the protective shell on the surface of the core is formed by rolling it with dry Portland cement, followed by hardening to strength not less than 0.12 MPa. 2. A concrete mixture for the manufacture of a building product, characterized in that it contains the aggregate according to claim 1, Portland cement, sand and water in the following ratio of components, wt.%:
Portland cement 15-25 sand 50-65 water 10-13 aggregate 2-20 3. A concrete mixture for the manufacture of a building product, characterized in that it contains the aggregate according to claim 1, Portland cement and water in the following ratio of components, wt.%:
Portland cement 20-35 water 10-15 aggregate 50-70 4. Concrete construction product, characterized in that it is made from a mixture according to claim 2 or 3.