RU2473517C1 - Crude mixture for making light concrete - 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 contains the following, vol. %: portland cement 11.8-21.4, 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 53.4-58.8, plasticising additive - Polyplast or Centrament 0.01-0.15, 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 heat-insulating and heat-insulating-structural purposes, in particular for the production of wall blocks of lightweight concrete 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 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 mammary 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 mixture for the preparation of lightweight concrete, including Portland cement, expanded vermiculite, a plasticizing additive 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, with expanded vermiculite used in the composition of two fractions with a ratio in the mixture 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 120-160 kg / m ³ , with the following ratio of components, vol.%: Portland cement 11.8-21.4, expanded vermiculite of the Tatarskoye field 53.4-58.8, plasticizing additive (Polyplast or Centroment) 0.01- 0.15, water - the rest.

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 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 preparation of lightweight concrete and its properties are shown in the following table.

Components Famous Composition
Content, wt.% The claimed compositions
Content by Volume Portland cement 18.0 21,4 11.8 Foamed granular polystyrene 0.5 Basalt fiber 0.3 Saponified wood resin 0.015 Plasticizing additive 0.01 0.15 0.1 Polyacryamide 0.01 Lignopan B-2 0.01 Expanded Vermiculite 67 53,4 58.8 Water 14,155 25.05 29.3 Density grade D, kg / m ³ 800 500 The compressive strength of concrete, MPa ≈2 3,5 2 Thermal conductivity λ, W / m · ° С 0,112 0,100

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. As a plasticizing additive, either Polyplast or Centrent is used. Polyplast is a naphthalene formaldehyde superplasticizer. Centerment - modified surfactants based on a polymer of polycarboxylate esters, a product manufactured by MC-Bauchemie.

The inventive concrete mix is prepared in a forced action mixer. The dosage of the components is carried out in the following sequence: first, Portland cement is dosed by weight; then vermiculite, water and a plasticizer by volume. 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, metered water and a plasticizing agent are added to the mixture. The final mixing of all components is 90-120 sec. The consistency of the prepared mixture is controlled by a Suttard device (melt is 160-170 mm). The finished vermiculite-concrete mixture is poured in one step flush with the edges of the mold having the size of a standard block. The molded products in the form are sent to the post-moisture treatment. After steaming, the products are redistributed - removed from the mold, 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. Moreover, the increase in strength is affected by the qualitative and quantitative composition of the raw material mixture, 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 the structure formation processes, which generally increases the strength of finished products and is confirmed by the results of X-ray diffraction analysis.

Thus, the advantage of lightweight concrete blocks from the claimed compositions is that the increase in strength with respect to the prototype for structural heat-insulating vermiculite concrete with a density of D800 kg / m ³ is 75%, and heat-insulating vermiculite concrete with a density of D500 kg / m ³ has a strength that meets the requirements of GOST 25820-2000. The thermal conductivity of vermiculite concrete of the claimed compositions is in the range of 0.100-0.112 W / m · ° C, which corresponds to class B - thermal insulation materials of medium thermal conductivity.

Claims (1)

The raw material mixture for the preparation of lightweight concrete, including Portland cement, expanded vermiculite, a plasticizing additive and water, characterized in that it uses expanded vermiculite from the Tatar deposit of the Krasnoyarsk Territory with a predominant magnesium oxide content and an increased degree of vermiculization, the expanded vermiculite being used as a part of two fractions with a ratio in the mixture 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 , and as a layer curing additive - Polyplast or Centiment in the following ratio of components, vol.%:
Portland cement 11.8-21.4 swollen vermiculite of the Tatar field 53.4-58.8 plasticizing agent Polyplast or Centration 0.01-0.15 water rest