RU2378218C2 - Raw composition for manufacturing of construction materials and products - Google Patents

Abstract

FIELD: construction. ^ SUBSTANCE: present invention is related to raw compositions intended for manufacturing of construction materials and products on their basis. Raw composition for manufacturing of construction materials and products, including magnesia binder, which includes caustic magnesite and aqueous solution of chloride magnesium with density of 1.19-1.3 kg/l, mineral filler and additive, contains, as mineral filler, mixture of loose substances with specified surface of 3000-6500 cm2/g, which consists of TPP flue ash, quartz sand, kaolin and hydrophobic surface-active substance - surfactant powder - copolymer: vinyl acetate/vinyl alcohol or vinyl chloride / ethylene, or vinyl chloride /ethylene/vinyl aurate and additionally contains water-reducing additive, and also stabilising and water-reducing additive - water soluble ether of cellulose at the following ratio of components, wt %: caustic magnesite 28.0-40.0, quartz sand 30.0-42.0, TPP flue ash 10.0-14.0, kaolin 1.0-4.0, specified surfactant 0.5-0.9, water-reducing additive 0.01-0.30, water soluble ether of cellulose 0.01- 0.02, specified aqueous solution of magnesium chloride the rest. Invention is developed in dependent claims of formula. ^ EFFECT: increased mobility, vital capacity, strength, reduced water absorption. ^ 4 cl, 1 tbl, 3 ex

Description

The invention relates to raw materials compositions intended for the manufacture of building materials and products based on them: self-leveling self-leveling floors, screeds, coatings, panels and plates for the external and internal cladding of buildings, staircases, various monolithic architectural and construction products of complex configuration; the composition can also be used to plug cracks in the walls of collapsing buildings.

Magnesia composite materials are widely and increasingly used in the construction industry. This is due to the fact that they have a unique set of properties: high mechanical strength, low abrasion, high adhesion to various building materials, incombustibility, anti-electrostaticity, dust-free, oil and oil resistance, shrinkage and high aesthetic and decorative qualities. However, building materials and products based on a magnesian binder (Sorel cement) are not sufficiently resistant to water, long-term atmospheric effects of high humidity, which limits their functionality and applications. In particular, they cannot be used for the exterior decoration of buildings and structures, the decoration of basements with high humidity and the possible seepage of groundwater. In the last decade, raw magnesia compositions have found wide application in the manufacture of industrial and decorative seamless bulk floors, screeds and various coatings. When mixing such raw compositions, they should form self-leveling mobile plastic masses spreading over a large surface and preserving viability for the time necessary for their full use. When hardening the mass, the resulting material and the building structure from it must have, along with high mechanical strength and low abrasion, a small amount of ultimate water absorption and high moisture resistance.

Self-leveling building mixtures based on magnesia binder are known (US Pat. RU 2163578, class C04B 28/30 of 03/21/2001), intended primarily for the manufacture of bulk floors, screeds and various building coatings.

The self-leveling building mixture (RU 2163578) contains a loose aggregate, an inert filler with a high specific surface and at least one stabilizing and water-retaining additive, and as a binder, caustic magnesite or caustic dolomite and a salt component representing at least crystalline hydrate or an aqueous solution one salt of a strong acid and a divalent trivalent metal.

The proposed mixture has high mobility, uniformity and good aesthetic properties, but has the following disadvantages.

The mixture has a short pot life (1 hour) during which it must be used. In the invention there is no data on water absorption and water resistance of building materials based on it. Strength properties are not fully represented (only compressive strength after seven days of solidification).

A known method of preparing a raw material mixture for the manufacture of building products (RU 2098381, class C04B 28/30 dated 10. 12.1997). The method includes mixing a magnesian binder with a filler, followed by mixing with a salt solution of magnesium chloride. The mixture has a composition (wt.%): Magnesian binder 40-50, bischofite solution with a density of 1.17-1.22 g / cm ³ - 22-33, and aggregate - the rest. In order to increase strength, water and frost resistance and reduce the amount of water absorption of the resulting materials, the magnesium chloride solution is repeatedly processed in a magnetic field of an apparatus with a strength of 160 to 340 kA / m before mixing.

This method of obtaining a raw mix using magnetization of saline solution allowed to increase the bending strength of the material by 40%, increase water resistance 3 times and reduce the amount of water absorption from 11.2% to 3.5%.

The disadvantages of the invention include:

- there is no data on the mobility and pot life of the closed mixture;

- fragmentary data on the strength of control samples are presented (only bending strength);

- there is no data on the water resistance of the samples;

- the method of multiple magnetization of saline in a special apparatus limits the possibilities of large-scale industrial production of the mixture and increases the cost of manufacturing building products.

A known composition for the manufacture of building materials (US Pat. RU 2079465, CL 04B 28/30 from 08/18/1997), containing magnesia binder, magnesium sulfate (epsomite), filler, surfactant, silicon-organic water repellent and water-soluble sulfates , and / or chloride of iron and / or aluminum.

The invention allows to obtain a magnesia composition with a reduced amount of water absorption (4%) and high compressive strength (up to 50 MPa), however, the viability, mobility of the magnesia mixture have not been studied, there are no data on bending strength, ultimate tensile strength. In addition, the achieved result in terms of water absorption is still insufficient.

Known raw mix (US Pat. RU N2130437, CL 04B 28/30, from 12/08/1999), including, wt.%: Caustic magnesite - 15-21.5; ground basic granulated slag - 24.0-28.5; ground blast furnace dust or blast furnace gas treatment slurry - 9.0-30.0; bischofite solution with a density of 1.3 g / cm ³ - 9.30-11.16; aluminosilicate additive (waste from mechanical cutting of decorative sections on the surface of crystal products) - 1.0-5.0, water (taking into account chemically bonded bischofite) - the rest.

This invention in its technical essence and the achieved result is the closest to the proposed and taken as a prototype.

This raw material mixture has a high mobility and viability in the closed state, and during curing it forms a material with a sufficiently high water resistance and compressive strength.

At the same time, the mixture has significant disadvantages:

- long viability time in a highly mobile state and a slow set of strength (the time before setting at 20 ° C is from 21 to 28 hours); this limits the possibility of using the mixture in the manufacture of bulk floors, coatings, screeds, etc., the composition additionally requires long-term monitoring and care before commissioning;

- a raw material mixture with a high content of slag and blast furnace dust or sludge from blast furnaces forms compressive but brittle materials. The invention does not have complete data on mechanical properties, in particular, on bending and tensile strength;

- there is no data on the water absorption of the composition;

- the use of waste from mechanical cutting of decorative sections of crystal products as raw materials to increase water resistance limits the possibility of large-scale industrial use of the mixture.

The objective of the proposed invention is the creation of a simple to manufacture and low cost self-leveling raw material composition with high mobility and optimal pot life, providing (along with high mechanical strength) low water absorption and high water resistance of building materials and products created on its basis.

The object of the invention is achieved due to the fact that the raw material composition for the manufacture of building materials and products, including a magnesian binder, which includes caustic magnesite and a salt component in the form of an aqueous solution of magnesium chloride, a mineral filler and an additive, contains an aqueous solution of magnesium chloride with a density 1,19-1,30 kg / l, as a mineral filler it contains a mixture of granular substances with a specific surface of 3000-6500 cm ² / g, consisting of fly ash TPP, quartz sand, kaoli on hydrophobic surfactant - surfactant powder of a copolymer: vinyl acetate / vinyl alcohol, or vinyl chloride / ethylene, or vinyl chloride / ethylene / vinyl laurate, and additionally contains a water-reducing additive, as well as a stabilizing and water-retaining additive - water-soluble cellulose ether in the following ratio of components , wt.%:

Caustic Magnesite 28.0-40.0 Quartz sand 30.0-42.0 TPP fly ash 10.0-14.0 Kaolin 1.0-4.0 Specified Surfactant 0.5-0.9 Water reducing additive 0.01-0.30 Water soluble cellulose ether 0.01-0.02 Magnesium Chloride Aqueous Solution density 1.19-1.30 kg / l Rest

The TPP fly ash used in the composition contains in wt.%:

SiO ₂ 30-48 Al ₂ O ₃ 11-35 Fe ₂ O ₃ 9-10 Cao 4-12 MgO 0.7-6.0 K ₂ O 0.7-1.2 Na ₂ O 0.3-0.8 TiO ₂ 0.6-0.8

As a water-reducing additive, the feed composition contains acetone or a salt of sulfonated naphthalene formaldehyde or melamine formaldehyde polymers.

As a water-soluble cellulose ether, it contains methyl hydroxyethyl or ethyl hydroxyethyl cellulose.

Caustic magnesite is a component containing active magnesium oxide (MgO) with a mass fraction of 0.80-0.95 ("Caustic magnesite powders", GOST 1216-87). Salt component - technical crystalline hydrate of magnesium chloride (MgCl ₂ · 6H ₂ O), according to GOST 7759-73.

Studies have shown that dusty particles of fly ash increase the ductility of the closed mass, reduce the maximum water absorption and increase the water resistance of the hardened component if the ash content does not exceed 15-20% of the total mass.

When ash and quartz sand are used together, the optimum ratio is SiO ₂ : ash ≈3. An increase in the ash content above the specified values causes an increase in the viscosity of the composition and a decrease in the strength characteristics of the material, and relatively low ash concentrations (less than 10%) slightly reduce the amount of water absorption.

The use of fly ash as a filler not only improves the properties of the raw material composition, but also reduces the cost of production; in addition, the disposal of this technogenic waste product positively affects the environmental situation.

Finely dispersed kaolin (with a dispersion of 50-200 microns) enhances the plasticity of the closed raw material mass, increases its viability time. In addition, hydrophilic particles of kaolinite Al ₂ (Si ₂ O ₅ ) (OH) _4, when interacting with water, are able to absorb and retain H ₂ O molecules, swelling and clogging the capillaries and pores of the composition; the moisture resistance of hardened magnesia stone increases. The optimal concentration of kaolin in the proposed composition is 1.0-4.0% of the total mass; its higher content sharply reduces the mechanical characteristics of the material.

To obtain magnesia concrete and products based on the raw material composition, granite, granite gneisses, dolomite, pebble, marble, shungite, crushed glass, and ceramics can be additionally used as fillers.

The manufacturing technology of the raw material composition includes operations:

preparation of raw materials, their dosing, mixing in a mixer for 5-7 minutes, caustic magnesite powder, filler and dry additives, the manufacture of an aqueous solution of magnesium chloride (bischofite) with a density of 1.19-1.30 kg / l, mixing with a bischofite solution of dry raw materials masses.

Case Studies

In the examples for the preparation of the raw material mixture used fly ash TPP composition, wt.%:

SiO ₂ 35 Al ₂ O ₃ 35 Fe ₂ O ₃ 10 Cao 12 MgO 6.0 K ₂ O 1,0 Na ₂ O 0.8 TiO ₃ 0.2

Example 1

To prepare 100 kg of the raw material composition, 28.0 kg (28 wt.%) Of caustic magnesite are taken; filler with a specific surface of 4000 cm ² / g obtained by mixing - 42, 0 kg (42 wt.%) silica sand (fractions of 0.1-0.2 mm); 14.0 kg (14 wt.%) Fly ash (specific surface 3500 cm ² / g), 4 kg (4.0 wt.%) Kaolin (specific surface 5000 cm ² / g); 0.01 kg (0.01 wt.%) Of ethyl hydroxyethyl cellulose ether, 0.9 kg (0.9 wt.%) Of a surfactant — vinyl acetate / vinyl alcohol powder with a specific surface of 5000 cm ² / g; 0.01 kg (0.01 wt.%) Sulfonated melamine-formaldehyde polymer, 11.08 kg (11.08 wt.%) Of an aqueous solution of magnesium chloride with a density of 1.19 kg / l.

The dry components of the mixture and additives are mixed in a mixer for 5 minutes. Next, the mixture is shut with a solution of magnesium chloride.

Closed raw material composition of this composition is a mobile self-leveling building mixture; spread, estimated using a Suttard viscometer, 24.5 cm; pot life of 3.5 hours.

When the mass hardens, a durable magnesia material (stone) is formed: at the age of 28 days, the compressive strength σ _cf = 38.8 MPa, the bending strength σ _ex = 10.8 MPa, and the tensile strength σ _rast = 6.7 MPa.

Water absorption of the material by mass W = l, 9%, water resistance coefficient Kv = 1.

Example 2

To prepare the raw material composition take 35.0 wt.% Caustic magnesite; filler with a specific surface of 5000 cm ² / g obtained by mixing 34.0 wt.% quartz sand (0.1-0.2 mm); 11.6 wt.% Fly ash with a specific surface area of 5000 cm ² / g; 2.0 wt.% Kaolin (4500 cm ² / g); 0.02 wt.% Sulfonated naphthalene formaldehyde polymer, 0.02 kg methylhydroxyethyl cellulose ether; 0.7 wt.% Surfactant - a powder of vinyl chloride / ethylene / vinyl laurate with a specific surface area of 6500 cm ² / g; 16.66 wt.% An aqueous solution of magnesium chloride with a density of 1.22 kg / l.

The dry components of the mixture and additives are mixed in the mixer for 5 minutes, then the mixture is closed with an aqueous solution of MgCl ₂ .

The closed raw material composition of this composition is a mobile self-leveling building mixture with a spread of 24 cm and a pot life of 3.5 hours.

When the mass is cured, a durable magnesia material (stone) is formed: at the age of 28 days, σ _cr = 44.6 MPa; _bending σ = 13.9 MPa; σ _tensile = 7.5 MPa.

The water absorption of the material by mass W = 2.0%, the coefficient of water resistance Kv = 1.

Example 3

To prepare the raw material composition take 40.0 wt.% Caustic magnesite; filler with a specific surface area of 5500 cm ² / g obtained by mixing 30.0 wt.% quartz sand (fractions of 0.1-0.2 mm); 10.0 wt.% Fly ash with a specific surface of 6000 cm ² / g; 1.0 wt.% Kaolin (4000 cm ² / g); 0.02 wt.% Methylhydroxyethyl cellulose ether 0.30 wt.% Acetone; 0.5 wt.% Surfactant powder of a vinyl chloride / ethylene copolymer with a specific surface of 6000 cm ² / g; 18.18 wt.% An aqueous solution of magnesium chloride with a density of 1.30 kg / l.

The dry components of the mixture and additives are mixed in the mixer for 5 minutes, then the mixture is closed with the prepared aqueous solution of magnesium chloride.

The closed composition of this composition is a self-leveling mass (23 cm spread) with a pot life of 3 hours and 15 minutes.

When the mass is cured, a strong stone material is formed: at the age of 28 days, σ _cr = 53.7 MPa, σ _bend = 17.4 MPa, σ _stretch = 9.3 MPa. Water absorption by weight W = 2.0%, water resistance coefficient Kv = 0.97.

The raw mix can be delivered to construction sites in a dry form (a mixture of dry components and additives) and shut there with an aqueous solution of magnesium chloride. The pot life of the reclaimed raw material composition allows it to be manufactured in places remote from construction sites and transported to its destination.

The manufacture of building structures such as screeds, floors, various coatings is done by pouring the closed composition onto a surface prepared in a certain way. The composition spontaneously equalizes under the influence of gravitational forces. During curing, the magnesia composition gains strength of 30-50% of its maximum value in 1 day, and a full set of strength occurs in 28 days.

Various building products, including complex configurations, can be made from the magnesia closed composition. Formation of the composition is carried out (depending on its consistency) by methods: casting into molds (when the standard cone is OK more than 16 cm), vibration (OK more than 2, but less than 5), vibrocompression, pressing, thrombosis (tough mixture, more viability).

The table shows the main characteristics of the raw materials compositions of the proposed technical solution and prototype.

The proposed raw material composition combines the properties of high mobility and self-leveling during the optimal time for its use (3.5 h), low water absorption limit (1.9-2.0%) and high water resistance (Kv = 0.97-1 , 0) materials and products based on it, which expands the range of use of magnesia compositions.

A comparative analysis of the proposed and known technical solutions shows (table):

- self-leveling mixture has an optimal pot life (≈3.5 hours, instead of 21-28 hours (RU 2130437, prototype)),

- the value of water resistance KV = 0.97-1.0, and in the prototype 0.75-0.90,

- the technology for obtaining the raw material composition is simple, and the use of technogenic production wastes (fly ash of TPPs) in it reduces the cost of production and positively affects the environment.

Thus, the claimed composition of the raw material composition and the complex of its properties are interconnected by a single inventive concept, leading to the achievement of the obtained technical result, which consists in creating a raw composition with a unique set of properties: when mixed, it is able to spontaneously spread over the surface and even out defects, while maintaining viability for an optimal time, and when it hardens, a durable building material or product with a low water value is formed absorption and high water resistance.

The results of the proposed technical solution and prototype Technical solution Pot life, h, at 200 С Water absorption by weight (%) In durability * (kv) Strength **, MPa (28 days) σ _{compression bending} σ σ _stretched Example 1 3.7 1.9 one 38.8 10.8 6.7 Example 2 3,5 2.0 one 44.6 13.9 7.5 Example 3 3.2 2.0 0.97 53.7 17.4 9.3 RU 2130437 prototype 21-28 - 0.75-0.95 78-96 - - * the water resistance coefficient Kv was determined as the ratio of the strength of samples saturated with water for 4 days to their strength when cured in air for 28 days (GOST 10060.0),
** measurements in accordance with GOST 18105-86.

Claims (4)

1. Raw composition for the manufacture of building materials and products, including magnesia binder, which includes caustic magnesite and a salt component in the form of an aqueous solution of magnesium chloride, a mineral filler and an additive, characterized in that it contains an aqueous solution of magnesium chloride with a density of 1.19 -1.30 kg / l, as a mineral filler it contains a mixture of granular substances with a specific surface area of 3000-6500 cm ² / g, consisting of fly ash of thermal power plants, quartz sand, kaolin and a hydrophobic surface-active substance - surfactant - copolymer powder: vinyl acetate / vinyl alcohol, or vinyl chloride / ethylene, or vinyl chloride / ethylene / vinyl laurate and additionally contains a water-reducing additive, as well as a stabilizing and water-holding additive - water-soluble cellulose ether in the following ratio, wt.%:
Caustic Magnesite 28.0-40.0 Quartz sand 30.0-42.0 TPP fly ash 10.0-14.0 Kaolin 1.0-4.0 Specified Surfactant 0.5-0.9 Water reducing additive 0.01-0.30 Water soluble cellulose ether 0.01-0.02 Magnesium Chloride Aqueous Solution density 1.19-1.30 kg / l Rest 2. The raw material composition according to claim 1, characterized in that the fly ash of the TPP contains, wt.%:
SiO ₂ 30-48 Al ₂ O ₃ 11-35 Fe ₂ O ₃ 9-10 Cao 4-12 MgO 0.7-6.0 K ₂ O 0.7-1.2 Na ₂ O 0.3-0.8 TiO ₂ 0.6-0.8 3. The raw material composition according to claim 1, characterized in that as a water-reducing additive it contains acetone or a salt of sulfonated naphthalene formaldehyde or melamine formaldehyde polymers. 4. The raw material composition according to claim 1, characterized in that as a water-soluble cellulose ether it contains methyl hydroxyethyl or ethyl hydroxyethyl cellulose.