RU2569422C1 - Wood-cement mix - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: wood-cement mix contains as an inorganic additive wastes of mechanical processing of talc chlorite in the form of a powder with particles of size of not more than 500 micrometers, including up to 0.02 wt % of particles with size of up to 0.5 micrometers, including nanoparticles, Portland cement, ground wood, polypropylene fibres, at the following ratio of components, wt %: Portland cement 33-42, sawdust 43-50, talc chlorite 5-6.9, liquid glass 5-7.5, calcium chloride 2.4-5, polypropylene fibres 0.1-0.2. Water is added to the specified mix to produce water-cement ratio of 0.8-1.2.

EFFECT: increased strength and ecological compatibility of material from proposed mix.

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Description

The proposed technical solution relates to wood-cement mixtures, which contain inorganic binders and are used for the manufacture of structural and heat-insulating materials in low-rise construction, corresponds to IPC С04В 28/00.

Known arbolite mixture according to patent RU 2455264 [1], containing cement, wood crushed, lime, foaming agent, liquid glass and sheet ground glass. However, to obtain this mixture, resources are required for the production of wood chips and ground flat glass, which negatively affects the characteristics of this mixture according to the criteria of resource saving and energy efficiency.

Known sawdust according to patent RU 2106322 [2] for the manufacture of building products, including, by weight. %: Portland cement 30, hydrated lime 5, fine gravel or sand 10, sawdust 30, clay 5 and water 20. When using Portland cement grade 500, sawdust concrete compressive strength reaches 2.1 MPa. However, gravel and sand increase density and reduce the thermal insulation properties of products from this mixture. In addition, sawdust from this mixture has a low strength.

A known composition for the manufacture of building blocks according to the application RU 93058241/33 [3], containing (wt.% In dry condition): sawdust up to 70%, cement 20-50%, lime up to 20%. However, such a composition does not provide sufficient strength of the building blocks.

Known arbolitic mixture according to patent RU 2466952 [4], which contains wood crushed, gypsum, soap-oil, fiberglass, cut into pieces of 3-15 mm. In this case, the fiberglass segments distributed in the mixture perform the function of dispersed reinforcement of products from this mixture, which reduces crack formation and, as a result, increases the strength of blocks and plates from the mixture. However, to obtain this arbolite mixture, additional production of wood chippings is necessary, which negatively affects the characteristics of the products according to the criteria of resource conservation and energy efficiency. In addition, high strength and stiffness of building elements from this mixture are not achieved.

The closest analogue of the proposed technical solution, i.e. wood-cement mixture for the manufacture of building materials, is arbolite mixture according to patent RU 2476399 [5], which is adopted as a prototype. The specified mixture contains the following components, the amount of which is expressed in parts by weight: Portland cement 20-25; wood chippings 60.5-62; gypsum 1-1.5; lime 1-1.5; asbestos fiber 5-50 mm long 1-1.5; pre-baked and ground asbestos-cement waste 10-15, and the water-cement ratio is 0.9-1.1.

However, to obtain this arbolite mixture, firing and grinding of asbestos-cement waste is necessary, which negatively affects the characteristics of the products according to the criteria of resource saving and energy efficiency. In addition, asbestos in the form of fibers is a carcinogenic material, which significantly limits the scope of the mixture.

The technical result from the application of the proposed technical solution is to increase the strength of blocks and plates from the proposed mixture, as well as to improve environmental performance through the use of carcinogenic safe components and to increase the efficiency of the use of stone processing and wood processing waste.

This technical result is achieved due to the fact that the proposed wood-cement mixture containing crushed wood, Portland cement, inorganic additives, reinforcing elements in the form of fiber segments, characterized in that it contains polypropylene fibers, and as an inorganic additive contains waste mechanical processing of talchlorite in in the form of a powder with particles no larger than 500 micrometers in size, including up to 0.02% of particles up to 0.5 micrometers in size, including nanoparticles, in the following ratio of components in wt. %:

Portland cement 33-42 sawdust 43-50 talchochlorite 5-6.9 liquid glass 5-7.5 calcium chloride 2,4-5 polypropylene fibers 0.1-0.2

moreover, the water-cement ratio is 0.8 -1.2.

In FIG. 1 shows a sample of the proposed wood-cement mixture in the process of its functioning during compression tests.

In FIG. 2 shows a sample of the proposed wood-cement mixture after compression tests in the process of its operation when tested for thermal conductivity by the probe method.

These samples are made of the proposed wood-cement mixture, which contains components in various proportions, however, located in the above ranges and presented below in table 2.

Obtaining the proposed mixture includes the following technological operations.

Dosing of the mixture components is carried out. Moreover, at the time of filing for dosing, all components must have a positive temperature.

Polypropylene fiber is mixed in the form of segments from 8 to 30 mm long and from 0.08 to 0.3 mm in diameter with sawdust unsaturated with moisture to achieve uniform distribution of this fiber in the mixture. For mixing use, for example, an electric mixer for the preparation of mortars and concrete.

After a uniform distribution of the fibers in the sawdust, water is added with a temperature of not more than 20 ° C with calcium chloride dissolved in it.

With further stirring, Portland cement and stone waste in the form of talcahlorite powder are added to the mixture.

Then add liquid glass. These components are mixed until a homogeneous mixture is obtained, which forms are filled to obtain blocks or plates.

In winter, the forms should have a positive temperature, but not more than 40 ° C. The mixture in the molds is compacted, for example, using a vibrating press. In this case, the frequency and amplitude of vibration are selected so as to avoid delamination of the mixture.

Then the product is kept in molds until stripping strength is achieved. A sign of achieving stripping strength is the stability of the geometric shape of the product when it is exposed only to its own weight after being removed from the mold.

Then the product is kept for gaining sufficient strength for storage in the warehouse under natural conditions, at an air temperature of 12-35 ° C and a relative humidity of 30-70%. Tempering strength of products is achieved within 28 days.

The compressive strength of the samples at the age of 28 days is determined experimentally, for example, using the testing machine AG 50 kNX SHIMADZU. For the tests used samples of standard shape in the form of a cube with a rib length of 0.1 m (Fig. 1).

The compressive strength of the samples from the proposed mixture is at least 3.5 MPa, which is sufficient for use in the construction of low-rise buildings in accordance with established requirements [6-8].

The average value of the coefficient of thermal conductivity of the material from the proposed mixture in the product, dried to constant density in natural conditions, close to the operating conditions of real structures, determined by the probe method (Fig. 2), is 0.14 W / m · K.

The average density of the material of the products from the proposed mixture at the age of 28 days will be 835 kg / m ³ .

If the proportion of cement in the mixture is less than 33 wt. %, then the strength of the blocks and plates from this mixture will be insufficient. With an increase in the proportion of cement, strength increases. However, an increase in the proportion of cement in excess of 42 wt. % is inefficient, since the increase in strength becomes insignificant, but the density increases significantly and the thermal insulation properties of blocks and plates from this mixture deteriorate.

If the proportion of sawdust in the mixture is less than 43 wt. %, the density increases significantly and the thermal insulation properties of blocks and plates from this mixture deteriorate.

If the proportion of sawdust in the mixture is more than 50 wt. %, then to consolidate the particles of sawdust, an increase in the proportion of cement is required, which increases the density and degrades the thermal insulation properties of blocks and boards from this mixture.

If the proportion of talchochlorite in the mixture is less than 5 wt. %, then the effectiveness of its use is insufficient. With an increase in this fraction, the strength of the material from this mixture grows. However, if the proportion is more than 7 wt. %, then the growth of strength slows down and stops.

If the proportion of water glass in the mixture is less than 5 wt. %, then the effectiveness of its application by the criterion of strength is insufficient. With an increase in this fraction, the strength of the material from this mixture grows, however, if the proportion of liquid glass in the mixture is more than 7.5 wt. %, the effectiveness of its use decreases, the density of the product increases, the insulating properties deteriorate, and the increase in strength is negligible.

If the proportion of calcium chloride in the mixture is less than 2.4 wt. %, then the effectiveness of its use is insufficient. With an increase in this fraction, the effectiveness of its application increases, however, if its proportion is more than 5 wt. %, then the increase in the effectiveness of its use stops.

If the proportion of polypropylene fibers in the mixture is less than 0.1 wt. %, then the effectiveness of their use is insufficient. With an increase in their share, the strength of the product from the mixture grows due to the reinforcement of the material. However, if the proportion of fibers is more than 0.2 wt. %, then the increase in the effectiveness of their use stops.

To this mixture of components, water is added in an amount necessary to obtain a water-cement ratio in the range from 0.8 to 1.2. This ratio of water and cement (by weight) provides optimal conditions for the consolidation of the mixture with the formation of a sufficiently durable material. Reducing the amount of water does not ensure the full use of the properties of cement as a binder component. An increase in the amount of water leads to a decrease in the strength of the products from the mixture.

As crushed wood in the inventive mixture used sawmill waste in the form of sawdust without additional processing, which reduces the cost of obtaining the inventive mixture. All components of the claimed mixture are environmentally friendly.

Talcochlorite in the form of a powder is formed during stone processing of the same mineral, also known as steatite, soapstone or potted stone. In terms of its chemical composition, talchochlorite is approximately two-thirds composed of silicon dioxide and magnesium oxide (http://www.o-kamne.ru/page36.php).

In the claimed mixture, the technical effect is achieved through the interaction of components, the quantitative ratio of which provides a synergistic effect, the final manifestation of which is to increase the efficiency of the use of environmentally friendly stone and woodworking waste, increase the strength of products (blocks and plates) from the proposed mixture, as well as simplify the technology and reducing the complexity of manufacturing a mixture and products from it. These factors positively affect the characteristics of products from the proposed mixture according to the criteria of resource conservation, environmental safety and competitiveness.

An example of the technical implementation of wood-cement mix. In the technical implementation of the inventive mixture, dusty mechanical stone processing wastes in the form of talcochlorite particles were used, the particle size distribution of which is quite uniform and includes particles with characteristic sizes of not more than 500 micrometers, including up to 0.02% of particles with a particle size of up to 0.5 micrometers, including nanoparticles.

When developing the inventive mixture, it was taken into account that sawdust is characterized by great variability of physico-mechanical properties, depending, among other factors, on the type of sawmill equipment. The claimed technical solution was implemented using sawdust, particle size distribution of which is shown in table 1.

For the technical implementation of the inventive mixture, Portland cement of the M500 grade was used in accordance with GOST 30515-97, liquid glass in accordance with GOST 13078-81 with a density of 1.45 g / cm ³ with a mass fraction of silicon dioxide of 34.2% and silicate module 2.6, technical calcium chloride in accordance with GOST 450 -77, polypropylene fibers in the form of segments 18 mm long according to TU 2272-001-90345062-2012, stone processing wastes in the form of particles of talchochlorite, tap water. Table 2 shows the compositions of the proposed mixture without taking into account water, since water is added taking into account the natural moisture content of sawdust until the required water-cement ratio is in the range from 0.8 to 1.2.

In accordance with the proposed method for producing the mixture, the dosing of the components is performed according to table 2. As indicated above, at the time of filing for dosing, all components must have a positive temperature.

To achieve the best distribution of polypropylene fiber in the finished mixture, it is mixed with sawdust not saturated with moisture. After a uniform distribution of the fibers in the sawdust, they should be closed with water and calcium chloride dissolved in it. With further stirring, Portland cement and stone waste in the form of particles of talchochlorite are added to the mixture. These components are mixed until a homogeneous mixture. Then add liquid glass. The mixing process stops when the finished mixture is fed into the mold.

In winter, the forms should have a positive temperature, but not more than 40 ° C. The mixture in the molds is compacted, for example, using a vibrating press. In this case, the frequency and amplitude of the vibrations are selected so as to prevent delamination of the mixture. Then the product is maintained until the stripping strength is achieved. Remove the product from the mold and incubate for curing in natural conditions, at an air temperature of 12-35 ° C and a relative humidity of 30-70%. Tempering strength is achieved within 28 days.

The compressive strength of the samples at the age of 28 days was determined experimentally using the AG 50 kNX SHIMADZU testing machine (Fig. 1). The samples had the shape of a cube with an edge of 100 mm.

The compressive strength of a series of samples was at least 3.5 MPa, which is sufficient for use in the construction of low-rise buildings in accordance with established requirements [6-8].

The average value of the coefficient of thermal conductivity of the material from the proposed mixture in the product, dried to a constant density in natural conditions, close to the operating conditions of real structures, determined by the probe method, is 0.14 W / m · K.

The average value of the density of the material samples at the age of 28 days was 835 kg / m ³ .

If we exclude from the mixture the above waste of talchochlorite, then the compressive strength decreases by about half. This is explained by the fact that in the proposed mixture due to the use of waste of talchochlorite and their synergistic interaction with other components, when their ratio in the proposed mixture is stated, the material structure and material strength are significantly improved, which is instrumental confirmed by mechanical tests for compressive strength (Fig. 1).

Bibliography

1. Arbolite mixture. Patent for invention RU 2455264. IPC С04В 38/10. Published: July 10, 2012.

2. Sawdust. Patent RU 2106322. IPC С04В 28/00; C04B 28/00; C04B 18:26; C04B 111: 20. Published: March 10, 1998.

3. The composition for the manufacture of building blocks, a building element and method of its manufacture. Application: RU 93058241. IPC E04C 2/10; B27N 3/02. Published: January 10, 1996.

4. Arbolite mixture. Patent RU 2466952. IPC С04В 28/02. Published: November 20, 2012.

5. Arbolite mixture. Patent RU 2476399. IPC С04В 28/04. Posted: 02.27.2013

6. GOST 19222-84. Arbolit and products from it. General specifications.

7. CH 549-82. Instructions for the design, manufacture and use of structures and products from wood concrete.

8. Nanazashvili I.Kh. Building materials from wood-cement composition // M. Stroyizdat, 1990. - 415 p.

Claims (1)

A wood-cement mixture for the manufacture of heat-insulating and structural building materials, containing crushed wood, Portland cement, inorganic additives, reinforcing elements in the form of fiber segments, characterized in that it contains polypropylene fibers, and as an inorganic additive contains waste from machining of talchlorite in the form of a powder with particles with a particle size of not more than 500 micrometers, including up to 0.02 wt.% particles with a particle size of up to 0.5 micrometers, including nanoparticles, in the following ratio , wt.%:
Portland cement 33- 42 sawdust 43-50 talchochlorite 5-6.9 liquid glass 5-7.5 calcium chloride 2,4-5 polypropylene fibers 0.1-0.2
moreover, the addition of water to the specified mixture is made to obtain a water-cement ratio equal to 0.8-1.2.

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