RU2793518C1 - Heat-insulating masonry mortar - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to the field of construction, in particular to compositions of lightweight masonry mortars intended for building cladding structures from effective small-piece elements. The heat-insulating masonry mortar contains Portland cement, ash, granulated blast-furnace slag, plasticizing and water-retaining additives, it additionally contains sand and, as granulated blast-furnace slag, ground granulated blast-furnace slag with a specific surface area of at least 280 m²/kg. As ash - ash from burning wood bark, screened on a sieve with a mesh size of 0.16 mm. As a plasticizing and water-retaining additive - a complex additive, represented by an aqueous solution with a density ρ=1.037 g/cm³, pH value = 6.5, in the form of a mixture of carboxylates of methacrylic acid copolymer, maleic acid copolymer and silicic acid sol with density ρ=1.021 g/cm³, pH value = 4.0 in the following ratio, wt.%: methacrylic acid copolymer carboxylate 24.5, maleic acid copolymer carboxylate 6.0, said silica sol 4.5 and water 65.0. With the following ratio of components, wt.%: cement 18-36, sand 20-26, ground granulated blast-furnace slag 5-15, ash from burning wood bark 9-15, complex additive 0.2-0.5, water - the rest.

EFFECT: increased strength and reduced water demand of heat-insulating masonry mortar.

1 cl, 1 tbl, 1 ex

Description

The invention relates to the field of construction, in particular to compositions of lightweight masonry mortars intended for building enclosing structures from effective small-piece elements.

Known lightweight composite material for restoration work with hollow microspheres (RU 2263643 S04V 28/04, S04V 111/20, 10.11.2005. Bull. No. 31). The raw mixture includes, wt. %: Portland cement -20.0-90.0, sand - no more than 30.0, superplasticizer based on sodium salt of naphthalenesulfonic acid with formaldehyde - no more than 1.7, water - 22.0-55.0, aluminosilicate microspheres with a diameter of 50- 250 microns and a wall thickness of 2-10 microns - 10.0-80.0 and vinyl acetate copolymer - 1.0-4.0.

The disadvantage of the known solution is the high water demand of the mortar mixture and low minimum strength.

Known fiber cement building material with lightening additives (US 7658794 SW 14/24, 2010-02-09). The raw mixture contains, wt. %: Portland cement - 5-80, aggregate - no more than 80% (for example, diatomites, blast-furnace slag, fly ash, lightening additive (volcanic ash, perlite, hollow ceramic microspheres)), cellulose fiber - 4-7, the rest is water.

The disadvantage of this technical solution is the low strength of the solution and high water demand, due to the use of lightening additives.

Closest to the proposed composition is a heat-insulating masonry mortar (CN 101643349 С04В 28/04, 2010-02-10), containing: Portland cement - 20 ... 65%, fly ash - 5 ... 50%, granulated blast-furnace slag - 0 ... 50% , aluminosilicate microspheres - 10 ... 23%, water-retaining additive - 0.1 ... 1%, plasticizing additive - 0.1 ... 1%, water - the rest.

The disadvantage of this solution is the low compressive strength - 5 MPa and the high water demand of the mortar mixture, due to the active mineral additive in the form of fly ash in large quantities (up to 50%).

The proposed technical solution is aimed at solving the problem of increasing the strength and reducing the water demand of the masonry mortar.

The technical result is achieved by the fact that the heat-insulating masonry mortar containing Portland cement, ash, granulated blast-furnace slag, plasticizing and water-retaining additives additionally contains sand, as granulated blast-furnace slag - ground granulated blast-furnace slag with a specific surface area of at least 280 m ² /kg, in as ash - ash from burning wood bark, screened on a sieve with a mesh size of 0.16 mm., as a plasticizing and water-retaining additive - a complex additive represented by an aqueous solution with a density of ρ=1.037 g/ ^cm ,5, in the form of a mixture of carboxylates of a copolymer of methacrylic acid, a copolymer of maleic acid and a sol of silicic acid with a density ρ=1.021 g/cm ³ , pH value pH=4.0, with the following ratio of components, wt.%:

methacrylic acid copolymer carboxylate - 24.5

maleic acid copolymer carboxylate - 6.0

the specified sol of silicic acid - 4.5

water - 65.0,

with the following ratio of components, wt.%:

portlandement 18-36

sand 20-26

specified ground granulated blast-furnace slag 5-15

specified ash from burning wood bark 9-15

the specified complex additive 0.2-0.6

water - the rest

The claimed set of essential features exhibits a new property - increased strength compared to the prototype and reduced water consumption of the mortar mixture. The claimed invention is industrially applicable and can be used in plastering and stone work.

The following is information confirming the possibility of carrying out the invention.

An example of a specific implementation.

As a lightening agent, finely dispersed ash from the combustion of wood bark, screened on a sieve with a mesh size of 0.16 mm, is used. Ash is a residue of mineral impurities in the form of a black-brown powder with fragments up to 1 cm, with an admixture of soot particles. X-ray phase analysis of the ash showed that it is presented mainly in the form of glass with crystalline phases of calcium oxide, iron oxide (II), magnetite, magnesioferrite, sodium metaplumbate. The chemical analysis of the ash showed the content of up to 80% carbonates, silicates and sulfates of calcium and magnesium, and up to 60% are calcium compounds, the rest are low-melting compounds of sodium, potassium, a small amount of iron compounds and other impurities. The ash was subjected to grinding and screening on a sieve with a mesh size of 0.16 mm.

As a filler, building sand is used according to GOST 8736 and ground granulated blast-furnace slag with a specific surface area of at least 280 m ² /kg. When smelting iron and steel, about a ton of granulated blast-furnace slag is produced for every ton of metal. During rapid cooling (granulation), glass is present in the slag, the content of which reaches 80% by weight or more. For example, granulated blast-furnace slag (Cherepovets) has an amorphous structure, contains gelenite, monticellite, spinel and other silicates, aluminates and aluminosilicates of calcium, magnesium and a small amount of iron and manganese compounds. Cherepovets blast-furnace slag was ground to a specific surface area of at least 280 m ² /kg. Granulated blast-furnace slag with a particle size of less than 5 mm has its own porosity, its bulk density is 800-900 kg/m ³ . Conducted studies of porosity by mercury porosimetry of granulated blast-furnace slag showed the predominance of pores with a size of about 50 microns, while in ground granulated blast-furnace slag, pores with a size of less than 10 microns occupy 80-85% of the total volume. Such pores improve thermal performance and to a lesser extent affect the decrease in strength characteristics. Mortar preparation:

1. Dose cement

2. Dosing ash

3. Dose building sand

4. Dose ground granulated blast-furnace slag

5. Prepare a plasticizing and water-retaining additive:

5.1 Dosing of methacrylic acid copolymer polycarboxylate

5.2 Dosing of maleic acid copolymer polycarboxylate

5.3 Dose the silica sol

5.4 Dosing water

All components dosed according to paragraphs 1 - 5.4 are transported to a paddle mixer, where they are mixed for 30 minutes. Then, the density of the aqueous solution and the pH value are controlled. Ready-to-use additive is transported to a storage tank.

6. Dose the resulting additive

7. Dosing water

8. Dosed cement, sand, ground granulated blast-furnace slag, ash, water in accordance with GOST 23732, the complex additive is thoroughly mixed until a homogeneous mortar mixture is obtained;

The resulting mortar mixture is used for plastering and stone work. The thermal conductivity coefficient was determined according to GOST 7076. The compressive strength was determined according to GOST 5802. The test results are presented in the table.

The complex chemical additive has an increased reactivity, because contains dispersions of silicon dioxide SiO ₂ in its composition, which leads to an increase in hydration processes during the hardening of the solution with the formation of calcium hydrosilicates such as okenite 3CaO⋅6SiO ₂ ⋅6H ₂ O, affillite 3CaO⋅2SiO ₂ ⋅3H ₂ O, crystallizing in the form of elongated fibers and needles All this has a micro-reinforcing effect on the emerging structure of the mortar, in addition, these hydrosilicates are characterized by sufficient hardness, which on the Mohs scale ranges from 4 to 5 units. The combined action of ground granulated blast-furnace slag in combination with a complex chemical additive containing nanodispersions of silicon dioxide SiO ₂ provides a super-total effect, which consists in creating a strong and durable structure.

The results obtained show that when all components are used together with an additive based on a mixture of carboxylates of copolymers of methacrylic and maleic acids and a sol of silicic acid, the compressive strength increases and the water demand of the mortar mixture decreases. At the same time, the solution acquires the properties of a heat-insulating material, which is characterized by a thermal conductivity coefficient λ = 0.18-0.2 W / m⋅K, close to effective small-piece elements (lightweight concrete blocks, effective ceramic bricks, stones, etc.), and can be recommended for masonry work, improving the thermal characteristics of brickwork. The convergence of the thermal conductivity coefficient of a more durable masonry mortar and effective building materials will make it possible to avoid "cold bridges" and increase the strength and heat-shielding characteristics of the building envelope.

Claims (4)

Heat-insulating masonry mortar containing Portland cement, ash, granulated blast-furnace slag, plasticizing and water-retaining additives, characterized in that it additionally contains building sand, as granulated blast-furnace slag - ground granulated blast-furnace slag with a specific surface area of at least 280 m ² /kg, as ash - ash from the combustion of wood bark, screened on a sieve with a mesh size of 0.16 mm, as a plasticizing and water-retaining additive - a complex additive represented by an aqueous solution with a density of ρ=1.037 g/cm ³ , pH value of pH=6.5 , in the form of a mixture of carboxylates of a copolymer of methacrylic acid, a copolymer of maleic acid and a sol of silicic acid with a density ρ=1.021 g/cm ³ , pH value pH=4.0 in the following ratio, wt.%: methacrylic acid copolymer carboxylate 24.5 maleic acid copolymer carboxylate 6.0 said silica sol 4.5 water 65.0 with the following ratio of components, wt.%: Portland cement 18-36 building sand 20-26 specified ground granulated blast-furnace slag 5-15 specified ash from the combustion of wood bark 9-15 specified complex additive 0.2-0.6 water rest