RU2473518C1 - Crude mixture for making light concrete articles - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to the industry of building materials and can be used in producing light concrete and articles for heat insulation and structural purposes, particularly for making wall blocks from light concrete for low-height construction. The crude mixture for making light concrete articles contains the following, vol. %: portland cement 8-10, expanded vermiculite from the Tatar deposit, Krasnoyarsk region, with predominant content of magnesium oxide and high degree of vermuculitisation, said expanded vermiculite being used in two fractions in ratio of 1:1, one of the fractions being 2 mm with packed density of 90-100 kg/m³, and the other being 1.25 mm with packed density of 120-160 kg/m³ 72-75, water - the balance.

EFFECT: high strength and environmental friendliness of technologically simple articles made from light concrete.

1 tbl

Description

The invention relates to the building materials industry and can be used in the manufacture of lightweight concrete and products of thermal insulation and structural purposes, in particular for the production of lightweight concrete wall blocks for low-rise construction.

Known raw mix for the production of lightweight concrete, including a composite hydraulic binder - perlite-lime-gypsum mixture composition, parts by weight: expanded perlite with a specific surface area S _beats = 5500-7500 cm ² / g, particle size 10-20 microns 70- 80, quicklime S _beats = 3500-4500 cm ² / g, particle size 30-60 microns 18-26, semi-aquatic gypsum S _beats = 3500-4500 cm ² / g, particle sizes 30-60 microns 2-6 and aggregate - expanded perlite crushed stone 40-60, while lightweight concrete obtained from the above mixture, additionally containing, parts by weight: hardening accelerator - sulphate or chloride full-time or alkaline-earth metal and water to 0.33 A / F = 0.9-1.1, has a density of 600-650 kg / m ³ (RF Patent №2399598 C2, priority date 25.06.2008, publication date 27.12. 2009, author Dobrovolsky V.N., RU).

The disadvantages of the known raw material mixture are: the complexity of the binder composition, due to the many components, and, accordingly, the increased technological and energy costs, as well as the lack of real strength characteristics and their ratio with density.

Known raw mix for the manufacture of lightweight concrete, adopted as a prototype, comprising the following components, wt.%: Portland cement 14.0-18.0, foamed granular polystyrene 0.5-1.0, basalt fiber 0.2-0.3 , saponified wood resin 0.01-0.015, plasticizing additive C-3 0.01-0.015, polyacrylamide 0.01-0.015, lignopane B-2 0.01-0.015, expanded vermiculite fraction 5-10 mm 67.0-73 , 0, water - the rest, while the compressive strength of products obtained from such a mixture is 2 MPa (RF patent No. 2379266 C1, priority date 04.12.2008, publication date 01.20.2010, author Schepo Chkina Yu.A., RU, prototype).

The disadvantages of the prototype are: the multicomponent raw material composition with adverse environmental characteristics and, as a result, the complexity and high energy intensity of the process, as well as the lack of indication of density, which is the main characteristic of lightweight concrete.

The objective of the invention is to increase the strength and environmental friendliness of technologically simple products from lightweight concrete based on the inventive raw mix for the construction of heat-saving building envelopes.

To solve the problem in a raw material mixture for the manufacture of light concrete products, including Portland cement, expanded vermiculite and water, according to the invention, it uses expanded vermiculite from the Tatarskoye deposit in the Krasnoyarsk Territory with a predominant magnesium oxide content and an increased degree of vermiculization, and the expanded vermiculite is used in consisting of two fractions in a ratio of 1: 1, one of the fractions of 2 mm with a bulk density of 90-100 kg / m ^3, the other fraction of 1.25 mm with a bulk density of 120-160 kg / m ^3, n and the following component ratio,% vol:. 8-10 Portland cement, expanded vermiculite Tartar deposit 72-75, remainder water.

The expanded vermiculite of the Tatar deposit of the Krasnoyarsk Territory, used in the raw material mixture, has the following chemical composition, wt.%: SiO ₂ 40.29-40.42; Al ₂ O ₃ 10.48-10.98; Fe ₂ O ₃ + FeO 10.92-14.47; MgO 17.94-22.28; K ₂ O 3,9-4.08; other oxides - the rest. The above composition indicates the predominant MgO content in it compared to other oxides, which allows us to attribute the vermiculite of the Tatarskoye deposit to magnesium vermiculite and to a biotite series with a high degree of vermiculization.

Active industrial development of vermiculite from the Tatar deposit in the Krasnoyarsk Territory has been underway since 2009 by Sibver LLC, which produces expanded vermiculite of three grades: VVT 0.5, VVT 1.25 and VVT 2 with the corresponding fraction sizes 0.5 mm, 1.25 mm and 2 mm. In the inventive raw material mixture, a composition of two fractions of 1.25 mm and 2 mm in a ratio of 1: 1, which leads to a denser packaging, which increases the strength of the resulting material, is used.

An important feature of the vermiculite of the Tatar deposit is that the endothermic effects characterizing the process of expansion of vermiculite are negligible in it, possibly due to the lack of zeolite and crystallization water in comparison with vermiculites of other deposits. Comprehensive thermal analysis data show the main mass loss at temperatures of about 100 ° C; above these temperatures, the mass loss is less than 1%.

These features make it possible to judge the physicochemical processes occurring in vermiculite concrete of the claimed compositions using expanded vermiculite from the Tatar deposit.

The composition of the raw mixes for the manufacture of lightweight concrete and concrete properties are shown in the following table.

Components Famous Composition
Content, wt.% Suggested formulations
Content by Volume Portland cement 18.0 10 8 Foamed granular polystyrene 0.5 Basalt fiber 0.3 Saponified wood resin 0.015 Plasticizing additive 0.01 Polyacryamide 0.01 Lignopan B-2 0.01 Expanded Vermiculite 67 72 75 Water 14,155 eighteen 17 Density, kg / m ³ 850 750 The average compressive strength of concrete, MPa ≈2 6.5 5 Thermal conductivity λ, W / m · ° С 0.145 0.136

To prepare the concrete mixture, raw materials are prepared and dosed according to the table, and expanded vermiculite is used in two grades: VVT 1.25 and VVT 2 in a 1: 1 ratio with simultaneous dosing.

The inventive concrete mix is prepared in a forced action mixer. The loading of the components is carried out in the following sequence: first Portland cement, then vermiculite and water. At the same time, Portland cement with vermiculite is first mixed in the concrete mixer. The duration of mixing the dry components should be 90-120 seconds. Then the required amount of water is added to the mixture. The final mixing of all components is 90-120 sec. The finished vermiculite-concrete mixture is discharged with the mixer running through the shutter in the bottom into the receiving hopper of the molding press unit. The movable loading device (dispenser), making reciprocating movements, fills the mold with vermiculite-concrete mixture. The products are molded using a press. Recommended pressing pressure is 5-7.5 MPa. The molded products are placed in transport pallets with racks for preliminary exposure, after which they are fed with a bridge crane into a pit steaming chamber for heat treatment. The most effective TVO mode for vermiculite concrete of the claimed composition is a temperature rise of 2 hours, isothermal exposure of 4 hours at temperatures up to 80 ° C. After steaming, pallets with products are shipped to a warehouse for natural drying. Aging of products in an open warehouse is allowed at average daily temperatures of at least + 5 ° C. At lower temperatures, products are aged in a heated workshop on a specially equipped site.

The indicators in the table characterizing the properties of concrete indicate an increase in the strength of vermiculite concrete from the proposed compositions. At the same time, the qualitative and quantitative composition of the raw mix affects the increase in strength, as well as the influence of alkaline compounds that are part of the mineralogical composition of vermiculite of the Tatar deposit, which are catalysts for structure formation processes, which generally increases the strength of finished products and is confirmed by the results of x-ray structural analysis.

The advantage of lightweight concrete blocks from the claimed compositions is that according to GOST 25820-2000 lightweight concrete on expanded vermiculite refers to heat-insulating materials according to physicomechanical parameters, and the claimed compositions belong to structural and heat-insulating materials, having a concrete class of compressive strength B5 for grade by average density D900 and concrete class by compressive strength B 3.5 for the average density grade D800. The thermal conductivity of vermiculite concrete of the claimed compositions is in the range of 0.136-0.145 W / m · ° C.

Claims (1)

The raw material mixture for the manufacture of light concrete products, including Portland cement, expanded vermiculite and water, characterized in that it uses expanded vermiculite from the Tatarskoye deposit in the Krasnoyarsk Territory with a predominant magnesium oxide content and an increased degree of vermiculization, the expanded vermiculite being used in two fractions in a ratio of 1: 1, one of the fractions of 2 mm with a bulk density of 90-100 kg / m ^3, the other fraction of 1.25 mm with a bulk density of 120-160 kg / m ^3, with the following ratio of the components in, vol.%:
Portland cement 8-10 swollen vermiculite of the Tatar field 72-75 water rest