RU2782696C1 - Raw mix for the manufacture of silicate bricks - Google Patents

Abstract

FIELD: building materials.

SUBSTANCE: invention relates to the field of building materials, namely to the raw mix for the manufacture of silicate bricks. The raw mix for the manufacture of silicate bricks includes, wt.%: quartz sand 89.8-95, quicklime 4.8-10, two-fraction basalt fiber 0.2-1, and the two-fraction fiber has the first fraction with a diameter of 9-13 microns and a length 10-12 mm and the second fraction with a diameter of 9-13 microns and a length of 1.5-2 mm, with a weight ratio of the first and second fractions from 1:8 to 1:10. The invention has been developed in dependent claims.

EFFECT: increasing the compressive and flexural strength of silicate bricks.

4 cl, 2 dwg, 1 tbl

Description

[01] Field of technology

[02] The invention relates to the field of building materials, namely to the raw mix for the manufacture of silicate bricks and wall materials.

[03] State of the art

[04] Standard silicate mass of brick consists of sand (90-95 wt.%) and lime (5-10 wt.%). The characteristics of the finished brick depend on its composition and can vary over a wide range. Brick grade M300 has a compressive strength of 30.0 - 25.0 MPa, and a bending strength of 4.4 - 2.2 MPa. Brick brand M100 has similar characteristics in the range of 10.0 - 7.5 and 2.2 - 1.1. The characteristics of a brick can be changed by adding various components, in particular basalt fibers (fibers). Basalt fiber is a hygrophobic material, which improves the moisture resistance of products. The material has high chemical resistance, which increases the resistance of bricks to salt solutions, which also affect the change in strength characteristics during operation. In addition, due to the dispersed basalt fiber, the brick has a rough surface, which has a positive effect when processing brickwork with protective materials.

[05] The use of basalt fiber in concrete formulations is widely known in the art. So, from the patent of the Russian Federation for the invention RU 2480428, a concrete mixture is known, including water, Portland cement, quartz sand, basalt fiber with a diameter of 13-17 microns and a length of 6-12 mm, the superplasticizer "Polyplast SP-4". Basalt fiber undergoes a special treatment, as a result of which a fiber fraction 6-12 mm long enters the mixture. It is assumed that thanks to the basalt fibers, it is possible to block the development of macrocracks due to adhesion to the cement matrix and the formation of strong neoplasms in the structure of the hardened concrete. However, the formation of macrocracks is a secondary process of ongoing changes in strength in the contact zone of the filler and mortar due to the difference in temperature deformations. At the same time, the analog does not prevent the formation of microcracks as the root cause of the decrease in strength.

[06] The use of basalt fibers in sand-lime brick compositions is also known in the art. In particular, in the Chinese patent CN 112723850, 04/30/2021, a composition is described, including ash, Portland cement, quicklime, sand, aggregate, setting retarder, modifiers, defoamer, polymer latex powder, basalt fiber, polypropylene fiber and water.

[07] The closest analogue of the invention is the raw mix for the production of silicate brick, disclosed in the patent of the Russian Federation RU 2556547, 10.07.2015 (hereinafter - D1). The mixture includes, in wt.%: quartz sand 85.0-88.0, quicklime 5.0-7.0 and composite reinforcement based on basalt fiber - 2-8. The diameter of the fibers is 6-32 mm, the length is 5-30 mm.

[08] The disadvantage of the known analogues is the formation of microcracks in the manufactured bricks, which reduce the strength properties of the product.

[09] Disclosure of the Invention

[010] The main technical problem to be solved by the present invention is the low strength of silica brick

[011] The technical result of the invention is to increase the strength properties of bricks by preventing the formation of both macrocracks and microcracks.

[012] To solve the technical problem and achieve the specified result, a raw mix for the manufacture of silicate bricks is proposed, including quartz sand - 89.8-95 wt.%, quicklime - 4.8-10 wt.% and two-fraction basalt fiber - 0, 2-1 wt.%. Two-fraction basalt fiber has a first fraction with a diameter of 9-13 microns and a length of 10-12 mm and a second fraction with a diameter of 9-13 microns and a length of 1.5-2 mm. The weight ratio of the first and second fractions is from 1:8 to 1:10.

[013] In addition, the specified technical result is achieved in private embodiments of the invention due to the fact that:

[014] - basalt fiber has a density of 2600-2800 kg/m ³ , an elastic modulus of 9100-11000 kg/mm ² and a residual strength of at least 100 kg/mm ² ;

[015] - quicklime has an activity of at least 70% by weight and a moisture content of not more than 5%;

[016] - quartz sand has a size of 0.2-2 mm.

[017] Unlike analogues, the claimed invention uses a two-fraction basalt fiber. Long sections of 10-12 mm with a diameter of 9-13 microns serve to block the development of macrocracks. Short segments with a length of 1.5-2.0 mm, commensurate with the size of the crystals, and a diameter of 9-13 microns serve to prevent the formation of microcracks and block their development in case of occurrence.

[018] The choice of fiber sizes is due to the following. With a fiber length of the first fraction less than 10 mm, the probability of the formation of new macrocracks increases, and with a length of more than 13 mm, the efficiency of their braking with the help of reinforcing fibers decreases. The length of the fibers of the second fraction of 1.5-2.0 mm is selected based on the average size of the crystals of the material. In this case, the fiber diameter of 9–13 μm is due to the processes of chemisorption interaction of thin basalt fibers with hydration products.

[019] The mass ratio of the first and second fractions 1:8 - 1:10 is associated with the density of formation of macro- and microcracks in the finished material. In the case of a ratio of less than 1:8, the effectiveness of resistance to large cracks may decrease, and at a ratio of more than 1:10, an increase in the formation of microcracks may occur.

[020] The amount of 0.2-1 wt.% basalt fiber introduced into the mixture is due to the best combination of strength properties, which is shown experimentally (see below).

[021] Thus, the given parameters of the fractional composition of the fiber provide the best strength and performance indicators of sand-lime brick, including compressive and bending strength.

[022] Brief Description of the Drawings

[023] The invention is illustrated by drawings, where:

[024] In FIG. 1 shows a diagram of the strengthening of microcracks in a brick obtained from a composition according to the claimed invention,

[025] In FIG. 2 shows a diagram of the strengthening of a macrocrack in a brick obtained from a composition according to the claimed invention.

[026] The elements in the figures are indicated by the following reference numbers:

1 - brick segment;

2 - microcrack;

3 - the second (fine) fiber fraction;

4 - the first (large) fiber fraction;

5 - macrocrack.

[027] the Implementation of the invention

[028] The claimed raw mixture consists of quartz sand (89.8-95 wt.%), quicklime (4.8-10 wt.%) and filler (0.2-1.0 wt.%) in the form of a two-fraction basalt fiber. It should be noted that water is not included in the composition of the raw mix, but is added during the production of bricks.

[029] Quicklime (calcium oxide) is used with an activity (content of active oxides) of at least 70% by weight and a moisture content of not more than 5%.

[030] Quartz sand is used pre-washed from impurities. It is preferable to use rock sand. Such sand has roughness and sharp corners, which improves adhesion to lime and increases the strength characteristics of the product. Sand should consist of grains of various sizes (from 0.2 to 2 mm). Grains of different sizes allow, when mixed, to form a denser packing, which also positively affects the strength characteristics.

[031] Basalt fiber is used as a mixture of two fractions. The first fraction of long fibers 10-12 mm and a diameter of 9-13 microns should have the following characteristics: density 2600-2800 kg/m ³ , modulus of elasticity 9100-11000 kg/mm ² and residual strength of at least 100 kg/mm ² . The second fraction of short fibers should have similar characteristics. It can be made from the same raw material as the long-fiber fraction, or by cutting long-fiber fibers. Both fractions are mixed in the ratio of weight fractions of the first and second fractions 1:8 - 1:10.

[032] Sand-lime brick is obtained in the following way. Quartz sand is mixed with ground quicklime, water is added and kept until the lime is completely slaked. Two-fraction basalt fiber is added to the resulting mass, additionally moistened and mixed. A brick is formed from the resulting mixture, which is subjected to autoclave treatment in an atmosphere of saturated steam at a pressure of 0.7-1.2 MPa and a temperature of 170-180°C in the mode of 2-7-2 hours.

[033] In the obtained brick (1), the first fraction (4) of basalt fiber provides blocking the development of macrocracks (5) (see Fig. 2), and the second fraction (3) of the fiber prevents the formation and blocks the development of microcracks (2) (Fig. . one).

[034] To confirm the effectiveness of the claimed composition, tests were carried out on the physical and mechanical properties of bricks in laboratory conditions. Sample 0 was made from a traditional composition without basalt fiber. Sample 1 was made according to the closest analogue (patent RU2556547) using basalt fiber in the form of reinforcement. Samples 2-7 were made on the basis of a two-fraction basalt fiber with the characteristics described above.

[035] The compositions of the proposed raw mix and the physical and mechanical properties of the obtained silicate brick are shown in the table.

[036] Table. The results of testing compositions for the manufacture of bricks

laboratory sample Composition, wt.%: Tensile strength, MPa sand lime fiber When compressed When bending 0 92 eight 0 8.5 1.8 one 92 6 2 8.8 2 2 89.9 ten 0.1 8.6 1.8 3 89.8 ten 0.2 11.4 2.8 four 92 7.5 0.5 18.2 3.6 5 94.2 4.8 one 24.4 4.2 6 95 3.5 1.5 10.5 2.0

[037] As can be seen from the results of the table, the best strength properties of bricks are provided in samples No. 3, 4 and 5, which correspond to the declared composition of the raw mix.

Claims (5)

1. Raw mixture for the manufacture of silicate bricks, including quartz sand, quicklime and basalt fiber, characterized in that a two-fraction basalt fiber is used, having a first fraction with a diameter of 9-13 microns and a length of 10-12 mm and a second fraction with a diameter of 9-13 microns and a length of 1.5-2 mm, and the weight ratio of the first and second fractions is from 1:8 to 1:10, while the components are introduced at the following ratios, wt.%: quartz sand 89.8-95 quicklime 4.8-10 two-fraction basalt fiber 0.2-1 2. A mixture according to claim 1, characterized in that it uses basalt fiber with a density of 2600-2800 kg / m ³ , an elastic modulus of 9100-11000 kg / mm ² and a residual strength of at least 100 kg / mm ² . 3. A mixture according to claim 1, characterized in that it uses quicklime with an activity of at least 70% by weight and a moisture content of not more than 5%. 4. A mixture according to claim 1, characterized in that it uses quartz sand with a fraction of 0.2-2 mm.

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