RU74384U1 - EMPTY OR POROUS GRANULATED FILLER FOR CONCRETE - Google Patents

Abstract

The invention relates to the construction materials industry, in particular the production of heat-insulating backfills and aggregates for concrete.

A method for manufacturing a hollow or porous granular aggregate is proposed, including the preparation of cores from crushed heat-insulating foam glass or crushed sound-proof foam glass with grain sizes of 3.0 ... 30.0 mm, coating them with powdery clay material and subsequent firing at 790-1050 ° C.

The present invention solves the problem of obtaining a durable and waterproof granular aggregate (when using even weakly and non-expandable clays) with preserved or reduced bulk density, to expand the raw material base for the production of heat-insulating fillings and aggregates for concrete.

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Description

The invention relates to the construction materials industry, in particular the production of heat-insulating backfills and aggregates for concrete.

Known hollow granular aggregate and a method for its manufacture, including the preparation of the core by swelling a granular mixture of ash and liquid glass at 350 ... 550 ° C, coating the core with a solution of liquid glass and cement-ash mixture and subsequent heat treatment [A.S. USSR No. 1573009, class C 04 B 14/24, 1986].

The disadvantages of this method and product are: low water resistance and strength of the resulting aggregate.

Closest to the proposed solution are porous granular aggregate and a method for its manufacture, including the preparation of a mixture of liquid glass and additives - amorphous silica and foaming agent; obtaining nuclei, coating them with a powdery clay material and subsequent firing [RF Patent No. 2263084, cl. 7 C 04 B 28/26, 2002].

The disadvantages of the prototype are: low strength (up to 0.51 MPa when squeezed in the cylinder) and low water resistance of the resulting porous granular aggregate (destroyed by water after 8 hours), high bulk density, you can use only limited types of clay.

The present invention solves the problem of obtaining a durable and waterproof granular aggregate (when using even slightly and non-expandable clays) with preserved or reduced bulk density, to expand the raw material base for the production of heat-insulating

Backfill and aggregate for concrete.

The technical result is achieved due to the fact that in the method of manufacturing a hollow or porous granular aggregate, including the preparation of cores, coating them with powdery clay material and subsequent firing, according to the proposed solution, crushed heat-insulating foam glass or crushed sound-proof foam glass with grain size 3 are used as cores 0 ... 30.0 mm, and firing is carried out at 790-1050 ° C.

The result is achieved using the obtained hollow or porous granular aggregate, consisting of a fired core coated with clay material, in which, according to the proposed solution, crushed heat-insulating foam glass or crushed sound-proof foam glass with a grain size of 3.0 is used .. .30.0 mm.

Comparison of the proposed method for producing a hollow granular aggregate with a prototype made it possible to establish that the proposed solution is distinguished by the replacement of cores made from a mixture of liquid glass, amorphous silica and foaming agent with crushed foam glass with a grain size of 3.0 ... 30.0 mm. The introduction of the proposed crushed foam glass and subsequent firing at 790-1050 ° C allows you to get a durable and waterproof hollow or porous granular aggregate (when using even weakly and non-swellable clays) with a reduced bulk density. Thus, the proposed solution has the criterion of "novelty."

In the study of other technical solutions, the use of crushed foam glass proposed by the authors with grain sizes of 3.0-30.0 mm in the manufacture of hollow or porous granular aggregates by firing at 790-1050 ° C and similar materials was not identified, therefore, the claimed solution does not follow explicitly a prior art manner

which allows us to conclude that the proposed solution meets the criterion of "inventive step".

When implementing the inventive method of manufacturing a hollow granular aggregate as a raw material, the following components were used:

1. Crushed heat-insulating foamglass (blowing agent - soot) and soundproofing foamglass (blowing agent - chalk), a fraction with grain sizes from 3.0 to 30.0 mm, obtained by crushing and screening of foamglass according to TU 5914-003-02066339-98 "Materials and heat-insulating building products ", produced at BSTU named after V.G. Shukhov (Belgorod). The bulk density of crushed heat-insulating foam glass of a fraction from 3.0 to 30.0 mm is 170 ... 200 kg / m ³ , sound-proof - 260 ... 280 kg / m ³ depending on porosity. To prepare a crushed product, you can use trimming and battle blocks of foam glass.

2. As clay material used loam of the Shebekinsky deposit, Belgorod region. Refractoriness 1195 ... 1290 ° С. Water solubility - 28.7% (according to GOST 9169-75). The main clay mineral is montmorillonite. The color after firing is greenish yellow. The chemical composition of the loam of the Shebekinsky field, wt. Uo: SiO ₂ . - 59.9, Al ₂ O ₃ - 8.6, TiO ₂ - 0.4, Fe ₂ O ₃ - 1.2, CaO - 10.1, MgO - 1.8, R ₂ O - 3.4, SO ₃ - 0.4, p.p.p. - 14.2. This clay belongs to low-expanding clays (increase in volume 1.1 ... 1.3) and cannot be a raw material for producing light porous aggregates.

Analyzing the results of physical and mechanical tests of a series of experimental samples, we can conclude that by the ability to form raw granules of optimal size for the production of hollow granular aggregate, it is necessary to use crushed foam glass with a grain size of 3.0 ... 30.0 mm.

The method of applying the clay component of the granules in the manufacture of a hollow or porous granular aggregate can

carry out in different ways: for example, by moistening the crushed foam glass with the subsequent application of powdered clay material on its surface by dusting, or by dipping dry crushed particles of foam glass in a clay suspension. The method of applying the clay component does not affect the quality of the final product obtained.

In the proposed solution, moistened (to a moisture content of 2.0-2.5 wt.%) Crushed heat-insulating foamglass with a grain size of 3.0 ... 30.0 mm was applied to a vibratory tray to a layer of Shebekinsky loam crushed to a particle size of less than 0.1 mm . In the process of moving the foamglass grains through the vibratory tray, granules with a size of 4.0 ... 32.0 mm were formed, which, due to low humidity (less than 2.2%), were immediately fed to the firing in a muffle furnace. The temperature was raised at a speed of 3 ° per minute to a temperature of 920 ° C with a shutter speed of 0.5 hours, i.e. modeled production conditions for expanded clay production [Moroz I.I. Technology of building ceramics. Kiev: "Vishka school", 1980. - P.89-128]. After this, the muffle was turned off, the fired granules were cooled together with the muffle at a speed of 2 ° per minute to room temperature. After cooling the granules, their density, water resistance and strength were determined; the strength of the granules was also determined after daily exposure to water in accordance with GOST 9758 (example 1, table).

Compositions 2 and 3 were prepared in a similar way, while monofraction grains of 3.0 and 30.0 mm in size were used as crushed heat-insulating foam glass.

In a similar manner, a hollow or porous granular aggregate was prepared using crushed soundproof foamglass (compositions 6-10) as a core, as well as the known composition 11 (prototype according to RF patent No. 2263084, class 7 C 04 B 28/26, 2002, mixture eleven).

The composition and properties of the obtained hollow or porous granular aggregates are shown in the table.

Composition and properties of granular aggregate No. p / p The size of the porous core, mm The density of the porous core of the raw granules, kg / m ³ Firing temperature, ° С The bulk density of the granules of a hollow or porous aggregate, kg / m ³ The compressive strength in the cylinder, MPa Type of granular aggregate After firing After exposure to water for 24 hours Core material: crushed heat-insulating foamglass one. 3.0 ... 30.0 170 920 327 1.97 1.88 hollow 2. 3.0 170 790 745 0.50 0.31 porous 3 30,0 170 1050 302 0.59 0.58 hollow four. less than 3.0 170 780 809 0.28 0.09 porous 5. more than 30.0 170 1100 368 0.19 0.18 hollow Core material: crushed soundproof foamglass 6. 3.0 ... 30.0 260 920 392 2.61 2.47 hollow 7. 3.0 260 790 782 0.59 0.41 porous 8. 30,0 260 1050 381 0.68 0.61 hollow 9. less than 3.0 260 780 874 0.39 0.11 porous 10. more than 30.0 260 1100 469 0.21 0.20 hollow Core material, wt.%: Flask - 53, liquid glass - 40, foaming agent - 7 11 (prototype 15.0 250 780 * 750 0.51 collapsed porous * - the firing temperature is selected by the authors experimentally, because the prototype is not indicated, but based on the composition of the core material, it can be assumed that the temperature of the prototype should not exceed 780 ° C, because with increasing temperature, deformations and destruction of the clay shell of the aggregate granules due to the appearance of extensive melts are observed.

Analysis of the data obtained from the test results of the properties of samples of hollow granular aggregates made by the present method shows the following.

1. Mixtures of compositions 1-3 and 6-8 meet the requirements of GOST 9758 "Inorganic porous fillers for construction work."

2. The use of crushed foam glass as cores in the formation of raw granules and subsequent firing allows to obtain high-quality waterproof and durable granular aggregate that can be used as heat-insulating fillings and aggregates for concrete (compositions 1-3 and 6-8).

3. To reduce the size of the cores of foam glass less than 3.0 mm is impractical, because the resulting hollow or porous granular aggregate has an increased bulk density and does not allow to obtain high-quality lightweight concrete and meets the boundary requirements of GOST 9758, therefore, compositions 2 and 7 are accepted as boundary.

An increase in the size of the foam glass cores of more than 30.0 mm is impractical because the strength of the resulting porous granular aggregate decreases due to excessive formation of the glass phase during the melting of the granule core and the appearance of surface defects in the structure of the ceramic coating during firing, therefore this size of the nuclei (compositions 3 and 8) is accepted as boundary.

4. To reduce the firing temperature of crushed particles of foam glass with a clay component deposited on their surface less than 790 ° C is impractical, because a sufficiently intense interaction of the glass-phase of the core with clay does not occur during firing, therefore, the strength and water resistance of the resulting aggregate decreases (mixtures 4 and 9).

Raising the firing temperature above 1050 ° C is also impractical, because a violation of the geometric dimensions of products during firing and a decrease in strength (compositions 3 and 6) are observed.

5. The use of crushed soundproof foamglass as cores in the formation of raw granules leads to an increased content of glass phase in the internal volume of the granules of optimal size (3.0-30.0 mm), because its density of the initial foam glass is higher than heat-insulating, which allows to obtain a more durable and waterproof filler.

6. By changing the firing temperature upon receipt of a hollow granular or porous aggregate, it is possible to form not only the internal structure of the obtained granules (porous or hollow), but also to regulate the whole range of physicomechanical characteristics of the obtained product — strength, thermal conductivity, bulk density, water resistance, etc.

The inventive method of manufacturing a hollow granular or porous aggregate in comparison with the prototype has the following advantages:

1) strength properties are preserved in some cases, and under optimal conditions they increase 2.2 ... 3.4 times; water resistance is high;

2) bulk density while maintaining the required physical and mechanical characteristics either remains or decreases by 1.2 ... 1.5 times compared with the prototype, which allows to obtain concrete with a lower density;

3) the hollow or porous granular aggregate obtained as a result of firing has a closed-vitrified internal surface with minimal volumetric defects, the external ceramic coating of the granules has high adhesion to any organic and inorganic binders.

4) the molding of raw granules based on a durable foam-glass core is much easier to carry out than when using prototype kernels.

The physicochemical nature of the technical solution to achieve the problem is as follows: the use of crushed foam glass as nuclei in the formation of raw granules allows for strong adhesion to the external clay coating due to the developed external surface of the foam glass formed by the porous structure. For this reason, the formed raw granules are easily formed on a vibrating tray and transferring without losing the ceramic layer.

During firing, the clay component of the raw granule, being on the surface, is easily dried, the processes of preparation for sintering occur without the participation of slow diffusion processes. Upon reaching the glass softening temperature and further heating of the granular material, the ceramic surface of the granule is sufficiently hardened and the glass phase is evenly distributed on the inner surface of the granule. With a further increase in temperature, the glass goes into a liquid state and actively interacts with clay particles along the entire inner surface of the granule (proved by microscopic and petrographic studies). The authors found that the high strength of the glass-coated inner surface of the granules and the result of the interaction of clay with the molten glass phase of the foam glass core at temperatures of 790 ... 1050 ° C determines the high performance characteristics of the obtained granular aggregate.

A method of obtaining a granular aggregate according to the prototype, including the use of cores consisting mainly of liquid glass, does not allow to achieve a high result, implemented in the inventive method, because the resulting composites have a low resistance to water.

Using the proposed method for the manufacture of hollow or porous granular aggregates and the resulting products in the building materials industry will allow not only to obtain a high-quality product, but also to expand the material base using low-intumescent and non-intumescent clays, as well as solve the problem of utilizing scraps and battle blocks generated during production and machining of foam glass, and this technology is not demanding on the purity of the starting materials.

Claims (1)

Burnt hollow or porous granular aggregate, consisting of a core coated with clay material, characterized in that it contains crushed heat-insulating foam glass or crushed sound-proof foam glass with a grain size of 3.0 ... 30.0 mm and is burnt at 790-1050 ° C.