RU2568445C1 - Wood-cement mixture for production of heat-insulating and construction building materials - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: wood-cement mixture contains sawdust with the size not coarser than 10 mm, including 85 wt % of particles with the coarseness from 1 to 5 mm inclusively, and as an inorganic filler the mixture contains wastes of mechanical stone milling in the form of marble particles with the coarseness not larger than 3 mm, including 75-95 wt % of particles with the coarseness from 1 to 2 mm, Portland cement, lime, water, fibre and additives, with the following component ratio, wt %: Portland cement 26-30; sawdust 30-34; lime 2-3; wastes of stone milling in the form of marble particles 4-5; liquid glass 3-6; aluminium sulphate 1-3; polypropylene fibres 0.05-0.2; water 25.95-26.8.

EFFECT: increase of strength, effective application of wood-sawing and stone-milling wastes and ecological safety.

3 dwg, 3 tbl

Description

The proposed technical solution relates to wood-cement mixtures that contain inorganic binders and are used for the manufacture of structural and heat-insulating materials in low-rise construction, corresponds to IPC C04B 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, wt.%: Portland cement 30, slaked lime 5, fine gravel or sand 10, sawdust 30, clay 5 and water 20. When using Portland cement grade 500, the strength of sawdust concrete at compression up to 2.1 MPa. However, gravel and sand increase density and reduce the thermal insulation properties of products from this mixture.

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, this composition does not sufficiently provide the strength of the building elements from this mixture.

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 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 efficiency of environmentally safe use of stone processing and woodworking waste, increase the strength of blocks and plates, as well as to simplify the technology and reduce the complexity of manufacturing the mixture and products from it.

This technical result is achieved due to the fact that sawmill waste was used as crushed wood - sawdust with particles no larger than 10 mm in size, including 85 wt.% Particles with a particle size of 1 to 5 mm inclusive and 15 wt.% - the remaining particles, and as an inorganic filler, the mixture contains mechanical stone waste in the form of marble particles with a particle size of not more than 3 mm, including 75-95 wt.% marble particles with a particle size of 1 to 2 mm, in the following ratio, wt.%:

Portland cement 26-30 sawdust 30-34 lime 2-3 stone waste marble particles 4-5 liquid glass 3-6 aluminum sulfate 1-3 polypropylene fibers 0.05-0.2 water 25.95-26.8

In FIG. 1 shows with increasing structure of the material from the proposed mixture. A ruler was used as a scale factor; the division price of the ruler is 1 mm.

In FIG. 2 shows with the same increase the structure of the material obtained, ceteris paribus, but without the addition of marble waste.

In FIG. 3 shows a block during compression tests.

The method of obtaining the proposed mixture includes the following process steps.

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 aluminum sulfate dissolved in it. When this is the mixing of the resulting mixture.

With further stirring, Portland cement, lime and stone waste in the form of marble particles 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 mold 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 15-40 ° C and a relative humidity of 50-80%. 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 (Fig. 3). For testing, samples of standard shape in the form of a cube are used.

The compressive strength of the samples from the proposed mixture is at least 2.5 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, is 0.13 W / m * K.

The average value of the density of the material samples at the age of 28 days will be 713 kg / m ³ .

A comparative analysis shows that the structure of the material from the proposed mixture (Fig. 1) is significantly more uniform. Thereby, a higher strength of the material from the proposed mixture is achieved.

If the proportion of cement in the mixture is more than 30 wt.%, Then the strength of the blocks and slabs from this mixture will be insufficient for the consolidation of sawdust particles. With an increase in the proportion of cement, consolidation strength increases. However, an increase in the proportion of cement in excess of 30 wt.% Is ineffective, since the increase in strength becomes insignificant, but the density increases significantly and the thermal insulation properties of blocks and slabs from this mixture deteriorate.

If the proportion of sawdust in the mixture is less than 30 wt.%, Then the density increases significantly and the thermal insulation properties of blocks and boards from this mixture deteriorate.

If the proportion of sawdust in the mixture is more than 34 wt.%, Then to consolidate the particles of sawdust, an increase in the proportion of cement is required, which leads to the claimed ratio of sawdust and cement in the mixture.

Moreover, if in the sawdust the fraction of particles smaller than 1 mm exceeds 15%, then the strength of the product from the wood-cement mixture is significantly reduced. In this case, to compensate for the decrease in strength, an increase in the proportion of cement is required, which increases the density of the product, reduces its thermal insulation characteristics. If in the sawdust the proportion of particles larger than 5 mm exceeds 15%, then the homogeneity of the material obtained from the wood-cement mixture is significantly reduced and, as a result, its strength decreases.

If the proportion of lime in the mixture is less than 2 wt.%, Then its effectiveness is insufficient. With an increase in the proportion of lime, the strength of the material from this mixture increases. However, if the proportion of lime in the mixture is more than 3 wt.%, Then the increase in the effectiveness of its use stops.

If the proportion of marble particles in the mixture is less than 4 wt.%, Then the effectiveness of their application by the criterion of strength is insufficient. With an increase in the proportion of marble particles, the strength of the material from this mixture grows, however, if the proportion of lime in the mixture is more than 5 wt.%, Their effectiveness decreases, the density of the product increases, and the thermal insulation properties deteriorate.

If the proportion of aluminum sulfate in the mixture is less than 1 wt.%, Then its effectiveness is insufficient. With an increase in the proportion of aluminum sulfate, its effectiveness increases, however, if its share is more than 3 wt.%, Then the increase in the efficiency of its use ceases.

If the proportion of polypropylene fibers in the mixture is less than 0.05 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 efficiency of their use stops.

The amount of water in the proposed mixture corresponds to a water-cement ratio of 0.8-1.1. This ratio of water and cement 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.

The technical result from the application of the proposed technical solution is to increase the efficiency of environmentally safe use of stone processing and woodworking waste, increase the strength of blocks and plates, as well as to simplify the technology and reduce the complexity of manufacturing the mixture and products from it. Using the proposed mixture provides the claimed technical effect due to the fact that the main components of the mixture are stone waste in the form of marble particles and sawmill waste in the form of sawdust without additional processing. In addition, special production of wood chips is not required. All components of the claimed mixture are environmentally friendly.

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 waste of stone processing and woodworking, increase the strength of products (blocks and plates) from the mixture, as well as simplify the technology and reduce 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 for the manufacture of building materials. 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.

According to table 1, the total fraction of particles with a particle size of 1 to 5 mm inclusive is for sawmills 1 and 2, respectively, 92.63% and 90.10%.

The granulometric composition of mechanical stone waste in the form of marble particles is presented in table 2.

We used Portland cement grade M400 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 aluminum sulphate purified in accordance with GOST 1296685, hydrated lime without additives according to GOST 9179-77, polypropylene fibers in the form of segments 18 mm long and 0.2 mm in diameter according to TU 2272-001-90345062-2012, stone processing waste in the form of marble particles, tap water. Table 3 shows the compositions of the proposed mixture.

The water-cement ratio for compositions 1 and 2 in table 3 is, respectively, 0.87 and 1.03.

In accordance with the proposed method for producing the mixture, the components are dosed, for example, 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 unsaturated with moisture. After a uniform distribution of the fibers in the sawdust, they should be closed with water and aluminum sulfate dissolved in it. Allow the sawdust to react with aluminum sulfate. With further stirring, Portland cement, lime and stone waste in the form of marble particles 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 mold 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 15-40 ° C and a relative humidity of 50-80%. 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. 3). The samples had the shape of a cube with an edge of 100 mm.

The compressive strength of a series of samples was not less than 2.5 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 0.13 W / m * K.

The average density of the material of samples at the age of 28 days was 713 kg / m ³ .

If we exclude from the mixture the above marble waste, then the compressive strength is reduced by half. This is explained by the fact that in the proposed mix due to the use of marble waste and their synergistic interaction with other components, when the stated ratio in the proposed mixture is significantly improved, the material structure improves, which follows from a comparison of enlarged photographs of the surface of the samples with the price of dividing a scale line of 1 mm, presented on FIG. 1 and 2.

Bibliography

1. Arbolite mixture. Patent for invention RU 2455264. IPC C04B 38/10. Published: July 10, 2012.

2. Sawdust. Patent RU 2106322. IPC C04B 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 93058241/33. IPC E04C 2/10; B27N 3/02. Published: January 10, 1996.

4. Arbolite mixture. Patent RU 2466952. IPC C04B 28/02. Published: November 20, 2012.

5. Arbolite mixture. Patent RU 2476399 IPC C04B 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)

Wood-cement mixture for the manufacture of heat-insulating and structural building materials, the components of which are chopped wood, Portland cement, lime, water, fiber, inorganic fillers and additives, characterized in that sawmill waste is used as chopped wood - sawdust with particles no larger than 10 mm, including 85 wt.% of particles with a particle size of 1 to 5 mm inclusive and 15 wt.% - the remaining particles, and as an inorganic filler, the mixture contains mechanical stone waste non-processing in the form of marble particles with a particle size of not more than 3 mm, including 75-95 wt.% marble particles with a particle size of 1 to 2 mm, in the following ratio of components, wt.%:
Portland cement 26-30 sawdust 30-34 lime 2-3 stone waste marble particles 4-5 liquid glass 3-6 aluminum sulfate 1-3 polypropylene fibers 0.05-0.2 water 25.95-26.8

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