Due to its characteristics, silicate brick is in demand in individual, rural construction and in the construction of general (commercial) facilities. It is suitable for the installation of columns and wall structures, both subjected to loads and self-supporting. The characteristics of silicate bricks are largely determined by the method of their manufacture. Silicate brick is made by autoclaving a mixture of lime (10%), sand (90%) and water. The high pressure hot steam treatment of the raw molded brick gives the artificial building material the properties of stone, but with perfectly precise dimensions.
Let's consider the main characteristics of silicate bricks.
- Frost resistance
- Water absorption
- Brick density
- Thermal conductivity
- Soundproofing
Sand-lime brick strength and marking
According to the strength criteria, silicate brick is produced in the following grades M - 75; 100; 125; 150; 200 and 250. Bricks M300 and M350 are sometimes found. The high compressive strength of silicate bricks (kg / cm2) is the main advantage of the wall material. The strength indicator (from 7 to 35 MPa) is reflected in the marking of the brick and is denoted by the letter "M". The linear range is represented by products of the brand from M 75 to M 200. The numerical value shows the value of the maximum allowable pressure in kilograms per 1 sq. see bricks. For example, a brick of the M 100 brand can withstand pressure / load without subsequent deformation of 100 kg per cm2. If we consider a one-story building, then the load on the walls rarely exceeds 100 kg / cm2, therefore, silicate stones of the M 100 brand are used for the construction of walls. But when erecting higher buildings, a brick is required that allows a large load - M150 or M200.
Frost resistance of bricks
Frost resistance of silicate bricks is measured in cycles and, along with strength, is an indicator of its durability. If in terms of strength silicate samples have a whole line of products, then only four types are made in terms of frost resistance, which are designated as F15, F25, F35, F50. Moreover, facing bricks are produced only in two grades - F35 and F50. The number (figure) in the marking indicates the number of freezes and thaws of silicate material in water. Frost resistance of ordinary bricks, for example, grade F25, must withstand at least 25 freezing cycles (t = -18 degrees C) and the same amount of thawing (t = + 20 degrees C) without signs of destruction - cracks or peeling of the surface.
The numbers in the brick frost resistance markings show its potential ability to withstand freeze cycles, and this data was obtained in rigorous laboratory tests. In nature, the saturation of the brick with moisture is not so intense, and the temperature drops from plus to minus are not as sharp as during tests. Therefore, with the right engineering solutions regarding steam and waterproofing, the durability of silicate bricks is significantly increased.
Water absorption
The water absorption of sand-lime brick directly depends on its porosity. The porosity of the product is influenced by the granularity of the components of the initial mixture, its moisture content and the value of the specific pressure during pressing. The water absorption of the silicate product should not exceed 13%. When facing bricks get wet from rain, the thermal conductivity of silicate bricks can increase several times, which reduces the thermal insulation parameters of the outer wall. The reduced resistance of the brick to moisture is smoothed out by treating it with hydrophobic impregnations. By acquiring water-repellent properties, the brick retains the ability to breathe. However, given the increased tendency of the material to absorb water, silicate bricks are not used in the construction of foundations, basements and premises, the operation of which takes place in a humid mode.
Brick density
The strength of the wall material is influenced by such an option as the density of the silicate brick. This value is determined by the ratio of the mass of one brick to its volume, which naturally includes the pores and voids present in the product. The fewer voids in the body of a silicate bar, the stronger it is.
Density of silicate brick, kg / m3:
- Corpulent - 1840 ... 1933
- Hollow - 1135 ... 1577
Thermal conductivity
In direct proportion to the density of a silicate sample, there is a coefficient of thermal conductivity of a silicate brick, which is in the range of 0.35-0.7 W / (mgrad.C).
The thermal conductivity coefficient of a silicate solid brick is 0.7-0.8 W / m * K, for a brick with technical voids - 0.66-0.68 W / m * K, and for a slotted brick - 0.4 W / m * TO. That is, the lower this indicator, the higher the thermal insulation properties of the brick.
Soundproofing
Silicate brick differs from ceramic in better sound insulation. The average sound absorption rate is 64 dB. Using such material quality as excellent sound insulation, silicate brick is successfully used in the construction of interior partitions.
As well as facing bricks, silicate bricks are produced in several types. Walls, columns, partitions are erected from ordinary bricks (250x120x65 mm and 250x120x88 mm). Face brick, white or with pigment, when laying the outer walls, serves as the texture of the building itself. The choice of brick (brand, size and texture) should be justified by the conditions for the future use of the building and the requirements of aesthetics. The correct choice of silicate material will allow the consumer to optimize the cost of construction / renovation of the facility, reach a more efficient level of the construction process and build a building that is comfortable inside, and outwardly modern and presentable.
The water absorption of bricks is one of the most important indicators of hygroscopicity in percentage terms.
The higher the hydroscopicity of the brick, the lower its strength.
This indicator demonstrates the porosity of the product, which depends on its composition.
After all, the hygroscopicity of a brick quite impressively affects the frost resistance of the material. For this reason, when the material is saturated with moisture, its strength will significantly decrease in comparison with dry material. To do this, it is necessary to take into account this important indicator when choosing a brick for the construction of a country estate.
In order to find out the hygroscopicity of a brick, the material is placed in an oven for several hours at a temperature of 110-120 ºС. After heating, the brick is cooled at natural temperature, then weighing is carried out. Then it is immersed in water for 2 days and weighed again. The difference in weight determines how much is absorbed into the material as a percentage. For building bricks, the increase in mass should not be exceeded by more than 5%, and for the finishing block, not more than 14%.
Building bricks are divided into 3 main types
Building bricks are divided into three types: concrete block, sand-lime and ceramic bricks.
- concrete block;
- silicate;
- ceramic brick.
Concrete bricks are made by pouring cement mortar into specially prepared forms. At the same time, it is not in great demand in construction due to its high weight, poor sound insulation, high thermal conductivity and high cost. Of the positive features of concrete bricks, one can note a low water absorption of about 5%, in some types 3%, excellent strength for masonry of load-bearing walls and resistance to rapidly changing atmospheric conditions.
89.2% of silicate brick consists of sand, the rest is lime and binders.
The silicate block contains 89.2% of sand, the rest is lime and binders. In some cases, a coloring pigment is added to the preform to give the block the desired shade. The water absorption of silicates sometimes reaches 15%. For this reason, it is not recommended to use in places with high humidity. Such as basements, laying foundations, baths, etc. The silicate block has good sound insulation, reasonable price and is strong enough for bearing walls. The disadvantage is the high thermal conductivity compared to ceramic bricks.
The dull mustard color of ceramic bricks indicates underfiring, and in some places black, on the contrary, indicates overfiring.
The ceramic block is made from a mixture of clays and by firing in a tunnel kiln at a temperature of 1000 ° C. The ceramic workpiece, fired to the required standards, has a reddish-brown color and emits a ringing sound with a slight impact. Defect can also be distinguished by the color of the ceramic blank. A dull mustard color indicates underburning, and in places black indicates overburning. According to the standard of a red ceramic block, the minimum water absorption should be 6%, but it can reach 14%. The optimal water absorption is 8%. The ceramic block has a layered structure. Water absorption is average. Due to the moisture absorbed by the ceramic brick between the layers and the impossibility of rapid release of water during the period of significant temperature changes and unfavorable weather conditions, the ceramic brick begins to deteriorate. At the beginning, small cracks appear, which subsequently develop into through cracks. As a result, ceramic brick loses its properties.
The most common brick is the well-known red or ceramic brick, which is obtained by firing clay and clay mixtures. Another 10% of the market belongs to silicate bricks, obtained from lime mortar hardened in an autoclave.
Regardless of the material, the basic characteristics of the bricks are the same. It:
- Strength- the main characteristic of bricks is the ability of the material to resist internal stresses and deformations without collapsing. It is denoted M(brand) with the corresponding numerical value. The numbers show what kind of load per 1 sq. Cm. can withstand a brick. Bricks of grades M100, 125, 150, 175 are most often found on sale. For example, for the construction of multi-storey buildings, bricks of at least M150 are used, and for a house with 2-3 floors, M100 bricks are enough.
- Frost resistance - the ability of the material to withstand alternating freezing and thawing in a water-saturated state, indicated by Mrz and is measured in cycles. During standard tests, bricks are immersed in water for 8 hours, then placed in a freezer for 8 hours (this is one cycle). And so on until the brick begins to change its characteristics (weight, strength, etc.). Then the tests are stopped and a conclusion is made about the frost resistance of the brick. A brick with a lower cycle is usually cheaper, but its performance is usually lower and is only suitable for southern latitudes. In our climate, it is recommended to use a brick of at least Mrz 35.
By body density brick is divided into hollow and corpulent... The more voids in the brick, the warmer and lighter it is. The thermal properties of the brick can also be imparted by the porosity of the material itself, and the internal pores contribute to better sound insulation. The development of modern technology is aimed at creating porous(saturated with pores) bricks.
The classic brick size is 250x120x65 mm, it is called single... This size is convenient for a bricklayer and is a multiple of a meter. There is a brick and a larger one - one and a half(its height is 88 mm), ceramic stones of double and many times larger sizes.
Brick color mainly depends on the composition of the clay. Most of the clays after firing become "brick" in color, but there are clays, after firing they acquire a yellow, apricot or white color. If you add pigment additives to such clay, you get a brown brick. Silicate brick, initially white, is even easier to color by adding pigments.
Let's consider the types, characteristics and purpose of bricks in more detail.
Silicate brick
In fact, silicate brick represents bars of silicate autoclaved concrete having the shape and size of a brick. It consists of approximately 90% lime, 10% sand and a small proportion of additives. Its advantage in comparison with ceramic is its low cost, the ability to provide a variety of shades. Disadvantages: sand-lime brick is heavy, not very strong, not waterproof, conducts heat easily. Therefore, it is inferior to ceramic bricks in its versatility and is used only in the laying of walls and partitions, but cannot be used in foundations, plinths, stoves, fireplaces, pipes and other critical structures.
The properties of silicate bricks are regulated by GOST 379-79 “Silicate bricks and stones. Technical conditions ". Its main characteristics:
- strength grade - М125, М150;
- frost resistance grade - F15, F25, F35;
- thermal conductivity - 0.38-0.70 W / m ° C.
Requirements for dimensions, quality, geometry and appearance of silicate bricks are similar to those for ceramic bricks.
The ratio of silicate and ceramic bricks is 15 and 85%, respectively. The only manufacturer of silicate bricks in our region is JSC "Pavlovsky Plant of Building Materials"... The modern assortment of the enterprise consists of both traditional white solid silicate bricks and new types of products (silicate hollow bricks, silicate wall hollow blocks). Since 1998 the enterprise has been producing textured bricks "Antik"® (with the effect of a stone wall of an old castle). Since 1999 - volumetric colored bricks and bricks with fillers that improve its thermal insulation properties. In July 2003, Pavlovsky Zavod SM CJSC produced the first batch of silicate hollow bricks. Among the main advantages of the new product are the weight of the product (thanks to 11 blind holes, the brick weighs only 2.5 kg) and low thermal conductivity.
Examples of modern silicate bricks produced by Pavlovskiy Zavod SM:
Solid brick
He building, normal, private- material with a small void volume (less than 13%). Solid bricks are used for laying internal and external walls, erecting columns, pillars and other structures that carry an additional load in addition to their own weight. Therefore, it must have high strength (if necessary, use a brick of the M250 and even M300 brands), be frost-resistant. According to GOST, the maximum frost resistance grade of such a brick is F50, but you can also find F75 brick. Strength is achieved not for nothing - solid brick has an average density of 1600-1900 kg / m³, porosity of 8%, frost resistance grade of 15-50 cycles, thermal conductivity coefficient of 0.6-0.7 W / m ° C, strength grade of 75-300. Therefore, the external walls, completely lined with solid bricks, require additional insulation. A solid red brick in a classic size weighs from 3.5 to 3.8 kg. One cubic meter contains 480 bricks.
Most of all building and solid bricks are produced by JSC "Lenstroykeramika"... This enterprise is the only producer of high-strength bricks of the M250, M300 brands in the region, intended for the construction of high-rise buildings.
Examples of solid bricks produced by the Lenstroykeramika plant:
Hollow brick
In accordance with its name, the main difference between this brick is the presence internal voids- holes or slots, which can have different shapes (round, square, rectangular and oval), volume (13-50% of the internal volume) and orientation (vertical and horizontal). The presence of voids makes this brick less durable, lighter and warmer, less raw materials are used for its manufacture. Hollow bricks are used for laying lightweight external walls, partitions, filling the frames of high-rise and multi-storey buildings and other unloaded structures.
The second, newest, way to ensure the lightness and warmth of the brick is porization... The presence of a greater number of small pores in the brick is achieved by adding combustible inclusions to the clay mass during its molding - peat, finely chopped straw, sawdust or coal, from which only small voids remain in the massif after firing. Often the brick obtained in this way is called lightweight or ultra-efficient. Porous brick provides better heat and sound insulation compared to slot.
Technical characteristics of ordinary hollow bricks: density 1000-1450 kg / m³, porosity 6-8%, frost resistance 6-8%, frost resistance 15-50 cycles, thermal conductivity coefficient 0.3-0.5 W / m ° C, strength grade 75 -250, color from light brown to dark red.
Hollow core specifications super efficient bricks ( NPO Keramika): density 1100-1150 kg / m³, porosity 6-10%, frost resistance 15-50 cycles, thermal conductivity coefficient 0.25-0.26 W / m ° C, strength grade 50-150, color of shades of red.
Examples of hollow and porous bricks produced by the Lenstroykeramika factories and the Keramika plant:
|
Hollow brick construction, voidness 42-45%. |
 Size (mm): 250x120x65 |
| It is used for the construction of external and internal walls of buildings and structures. It features five rows of voids, which reduces the consumption of masonry mortar by 20%. |
| Porous building stone 2NF |
 Size (mm): 250x120x138 |
| Advantages: excellent thermal insulation properties, soundproofing, less weight. It is used in the construction of external and internal walls, significantly increasing the heat-shielding properties of the house. Exterior walls made of porous stone are erected faster than walls made of ordinary hollow bricks, and the number of mortar joints is reduced. Its density is 30% less, it is lighter, which leads to a decrease in the loads on the foundation structure. With a smaller wall thickness of 640 mm, porous ceramic gives the same thermal insulation effect as a conventional brick wall of 770 mm. |
Facing brick
He facial and front... The main purpose of facing bricks is the laying of external and internal walls with high requirements to the wall surface. Accordingly, the facing brick has a strictly regular shape and a smooth, glossy surface of the outer walls. Cracks and surface delamination are not allowed. Usually, facade brick- hollow, and, consequently, its thermal characteristics are quite high. By selecting the compositions of clay masses and adjusting the timing and temperature of firing, manufacturers get a wide variety of colors. These color fluctuations may not be intentional, so it is more expedient to buy all the required amount of facing bricks immediately, in one batch, so that the entire cladding is uniform in color.
Costs for brick cladding more than plastering, but such a facade is much more durable than plaster. When using decorative bricks for interior walls, special attention is paid to cutting the seams. The standard dimensions of a facing brick are the same as for an ordinary brick - 250x120x65 mm.
Technical characteristics of facing bricks: density 1300-1450 kg / m³, porosity 6-14%, frost resistance 25-75 cycles, thermal conductivity coefficient 0.3-0.5 W / m ° C, strength grade 75-250, color from white to brown.
Examples of facing bricks:
| Front brick red (Pobeda plant) |
  Size (mm): 250x120x65 |
| Designed for masonry and simultaneous facing of external and internal walls of buildings and structures of any number of storeys. The strength properties of facing bricks make it possible to use it not only as a decorative material, but also as a load-bearing material along with ordinary bricks. |
|
Ceramic brick face hollow Euroformat |
 Size (mm): 250x85x65 |
| Euroformat- this is a modern standard for the size of a brick, which makes it possible to embody the European standard of efficiency, aesthetics and modernity in the Russian reality. Used for exterior and interior work. Euroformat is lighter than ordinary brick, which allows you to save on the construction of foundations, facilitates and speeds up the work of bricklayers |
Colored and figured bricks
This is a special kind facing brick, which is given a special shape, surface relief or special color to enhance the decorative effect. The relief can be simply repetitive, or it can be processed under "marble", "wood", "antique" (textured with worn or deliberately uneven edges). Shaped brick differently called curly that speaks for itself. Distinctive features of figured bricks are rounded corners and edges, beveled or curved edges. It is from such elements that arches, round columns are erected without any special difficulties, and the decor of facades is performed.
Among the enterprises of our region in the field of colored and figured bricks, the palm is again shared by NPO Keramika and "Victory Knauf"... The latter, last year, began the production of engobered bricks (three-dimensional colored brick, resistant to various kinds of influences) of an expanded color range.
Ceramic brick facial hollow colored and brown
| Cream front brick, dyed in bulk (Pobeda plant) |
  Size (mm): 250x120x65 |
| Cream is the original color and warmth of soft cream colors. Cream brick is intended for cladding external and internal walls. |
| Facing straw bricks with textured surface (Keramika plant) |
  Size (mm): 250x120x65 |
| Designed for facing the outer walls of buildings and structures of any number of storeys. The production technology allows achieving color uniformity. |
| Colored front bricks with textured surface (Ceramics plant) |
 Size (mm): 250x120x65 |
| Designed for facing the outer walls of buildings and structures of any number of storeys. The production technology allows achieving color uniformity. Color pink, gray, light green, green, yellow, light blue, blue |
|
Front brick with embossed surface "Reed", red ("Keramika" plant) |
  Size (mm): 250x120x65 |
| Used for facade and interior work. The front surface of the brick resembles reed stalks in texture and allows you to enrich the ceramic masonry with decorative strokes, to give it a picturesque expressiveness. |
|
Facing brick with a relief surface "Oak bark", red ("Keramika" plant) |
  Size (mm): 250x120x65 |
| Used for exterior and interior work. The texture of the brick surface resembles the bark of a tree, which determines the expressiveness and attractiveness of this material. |
| Facing bricks hollow figured red, brown |
 Size (mm): 250x120x65 |
| Figured brick- this is an original material for home decoration, allowing you to make any building individual. The use of shaped bricks avoids labor-intensive cutting operations for conventional facing bricks and provides architects with the broadest opportunities for creating individual architectural elements of facades: rounding and framing window and door openings, erecting arches and columns |
Large bricks
GOST defines it as ceramic stone... Standard ceramic stone, or double brick(as sellers often call it) - measures 250x120x138 mm. The advantage of ceramic stones is their manufacturability and efficiency. Large bricks can significantly speed up and simplify the masonry process. The highest achievement in the production of such bricks in our country was the products of the plant. "Victory of LSR", which has mastered the production of light and very large blocks under the RAUF trademark.
Such products have gone very far from the simplest brick, which was once molded by hand. Blocks of the "Pobeda LSR" plant even by eye look like very high-tech products.
Examples of ceramic blocks produced by the association "Pobeda LSR"
| Porous building stone 2,1NF RAUF |
 Size (mm): 250x120x138 * depending on the brand of stone |
| It is used in the construction of external and internal walls, significantly increasing the heat-shielding properties of the house. Advantages: excellent thermal insulation properties, soundproofing. Exterior walls made of porous stone are erected faster than walls made of ordinary hollow bricks, and the number of mortar joints is reduced. Its density is 30% less, it is lighter, which leads to a decrease in the loads on the foundation structure. With a wall thickness of 640 mm, porous ceramic gives the same thermal insulation effect as a conventional brick wall of 770 mm. |
| Porous building stone 4,5NF RAUF |
 Size (mm): 250x250x138 |
| Used in the construction of external walls. The use of this stone allows you to reduce the load on the foundation, increase the speed of masonry, and reduce the consumption of mortar. Aerated brick is lighter than usual, has a low density, low thermal conductivity. Possesses excellent thermal insulation properties. By softening temperature extremes, it creates a comfortable microclimate in the house. Its use in masonry increases labor productivity and helps to reduce heat loss. |
| Large-format super-porous stone 10,8NF RAUF |
 Size (mm): 380x253x219 |
| It is used in the construction of external walls in low-rise housing construction. The super-porous block is an ultra-modern building material and has all the advantages of Warm (porous) ceramics. |
| Large-format porous stone 10.8NF, additional RAUF |
 Size (mm): 380x253x219 Weight (kg): 17 Density (kg / m³): 800 Brand: M75, M100 Frost resistance : F50 Water absorption (%): 11 Thermal conductivity(W / m ° C) |
| Acts as an additional element in the construction of external and internal walls from Warm Ceramics. The porous block is lighter than usual, it has a low density, low thermal conductivity. Due to the excellent thermal insulation properties, temperature drops in the house are softened. Transport, production and technological costs are significantly reduced, the time spent on masonry is reduced by 2-2.5 times. |
| Large-format porous stone 11,3NF, additional RAUF |
|
Size (mm): 398x253x219 Weight (kg): 17,7 Density (kg / m³): 800 Brand: M75, M100 Frost resistance : F50 Water absorption (%): 11 Thermal conductivity(W / m ° C) |
| Acts as an additional element in the construction of walls made of Warm Ceramics. The porous block is lighter than a conventional block, which reduces the load on the foundation. It has a low density, low thermal conductivity. Due to its excellent thermal insulation properties, it softens the temperature drops in the house. Transport, production and technological costs are significantly reduced, the time spent on masonry is reduced by 2-2.5 times. |
| Large-format porous stone 14,5NF RAUF |
 Size (mm): 510x253x219 |
| It is the main material for the construction of walls of warm ceramics in low-rise housing construction. The porous block is lighter than usual, which allows to reduce the load on the foundation, it has a low density, low thermal conductivity. Due to its excellent thermal insulation properties, it softens the temperature drops in the house. Transport, production and technological costs are significantly reduced, the time spent on masonry is reduced by 2-2.5 times. |
Clinker brick
Clinker brick used for cladding plinths, paving roads, streets, courtyards, facade cladding. The latter can be especially noted - such a finish does not need repair for a long time, dirt and dust practically do not penetrate the surface structure, and there are more than enough variations in colors and shapes. Among the disadvantages of clinker are increased thermal conductivity and high cost. Clinker density 1900-2100 kg / m³, porosity up to 5%, frost resistance grade 50-100, thermal conductivity coefficient 1.16, strength grade 400-1000, color - from yellow to dark red.
Clinker bricks are pressed from dry red clay and fired before sintering at significantly higher temperatures than are customary for the manufacture of conventional building bricks. This ensures high density and durability of the clinker.
Fireclay brick
To avoid the rapid destruction of masonry in contact with an open fire, a brick that can withstand high temperatures is needed. He's called stove, refractory and fireclay... Fireclay bricks can withstand temperatures in excess of 1600 ° C. Its density is 1700-1900 kg / m³, porosity is 8%, frost resistance grade is 15-50, thermal conductivity coefficient is 0.6 W / m ° C, strength grade is 75-250, color is from light yellow to dark red. Fireclay bricks are made of classical, as well as trapezoidal, wedge-shaped and arched shapes. Such a brick is made from chamotte - refractory clay.
● Brick dimensions produced in other countries differ significantly from the sizes adopted in the main part of the space of the former USSR.
| in Germany | 240x115x71 | in the USA | 203x102x57 |
| in England | 215x102.5x65 | in Australia | 230x110x76 |
| in Sweden | 250x120x62 | in South Africa | 222x106x73 |
| in Romania | 240x115x63 | in India | 228x107x69 |
Brick strength grade |
● An important characteristic of a brick is its ability to transfer heat at different temperatures outside and inside the structure. There is such a concept - the coefficient of thermal conductivity. In numerical terms, it looks like the ratio of the amount of thermal energy lost per 1 meter of thickness of the structure with a temperature difference of 1 degree between the outer and inner surfaces. For example, solid brick has a thermal conductivity of 0.5-0.6 W / m ° C. Solid brick has a fairly high thermal conductivity and therefore it is much more profitable to use hollow brick - its coefficient is 0.32-0.39 W / m ° C. Air in voids has a lower thermal conductivity and walls can be built less thick. Although in connection with the use of more and more new thermal insulation materials in modern construction, the relevance of thermal conductivity has dropped somewhat, you should not underestimate the importance of this quality in bricks, just as you should not overpay extra money and neglect such an indicator as a decrease in labor intensity when performing construction work.
Frost resistance of bricks |
● Water absorption of bricks- a percentage value that shows how much moisture a given type of brick is able to absorb and hold. To find out the water absorption, the brick is kept in an oven at a temperature of 105-110 ° C for a certain time, cooled and weighed. After that, the brick is placed in water for a certain period of time and weighed again. The difference between these two weightings as a percentage is the water absorption of the brick.
Water absorption greatly affects the frost resistance of a brick - for example, a product with water absorption above 9% has low frost resistance.
In silicate bricks, water absorption can reach 15%, so it is not recommended to use it in places with high humidity (basement rooms, foundations), as well as ceramic bricks produced by the method of semi-dry pressing.
5 samples intended for testing for water absorption are dried to constant weight and, after cooling, weighed with an accuracy of 1 g. After that, the samples are placed in a vessel with water in one row on lining so that the water level in the vessel is at least 2 higher than the top of the samples. cm, and no more than 10 cm. In this position, the samples are kept for 48 hours. After that, it is removed from the vessel, immediately taken with a damp cloth / soft / and each sample is weighed. The mass of water flowing out of the pores of the sample during weighing shall be included in the mass of the water-saturated sample. Weighing of saturated samples should be completed no later than 5 minutes after removing the samples from the water. Water absorption by weight is calculated by the formula /% /:
where m 1 is the mass of a sample saturated with water, g;
m is the mass of the dried sample, g;
Water absorption is determined as the average of 5 results. The water absorption of the brick must be at least 8%.
1.4. Determination of brick frost resistance
Frost resistance of bricks is the ability of a material or product saturated with water to withstand repeated freezing and thawing in water.
Samples of bricks intended for testing for frost resistance are preliminarily dried to constant weight, and then saturated with water and weighed. In the freezer, the samples are placed in special containers or placed on the racks of the chamber, after the temperature in it drops to -15 0 C. From the beginning to the end of freezing for 4 hours, the temperature in the placement area should not be higher than -15 below -20 0 С.
After the end of freezing, the samples are taken out of the freezer and immersed in a bath with water at a temperature of 15 - 20 0 C. The duration of one thawing must be at least 2 hours.
Freezing and subsequent thawing of samples is one cycle. According to the number of cycles of alternating freezing and thawing without signs of destruction, a brick grade is established in terms of frost resistance.
To determine the degree of damage, the samples are inspected every 5 cycles after thawing.
The brick is considered to have passed the frost resistance test if, after a specified number of cycles of alternating freezing and thawing, the samples do not break or damage types are not found on the surface of the samples: delamination, peeling, through cracks, spalling. In case of significant chipping of edges and corners, check the loss of mass of the sample, which should not exceed 2%.
To determine the weight loss, the samples are dried after the last test cycle to constant weight.
Weight loss is determined by the formula /% /:
,
where m 1 is the mass of the sample, dried to constant weight before the start of frost resistance tests;
m 2 - the mass of the sample, dried to constant weight for frost resistance.
According to frost resistance, brick is subdivided into four brands: Мрз. 15, Mrz. 25, Mrz. 35, Mrz. 50.
2.Test of ceramic tiles for interior cladding
Tiles used for interior wall cladding are made according to GOST 6141-82 from clay dough by molding, firing and glazing the front surface.
Tiles are produced in rectangular and shaped shapes of various types / square, rectangular, angular, etc. /, for which their sizes are set / for example, square tiles - 150 
150 mm /.
The thickness of all tiles, except for skirting boards, must be no more than 6.0 mm, for baseboards - no more than 10.0 mm. The thickness of tiles from the same batch must be the same.
The permissible deviation in the thickness of tiles of one batch should not exceed 0.5 mm. The deviation of dimensions along the length of the edges of the tile is allowed no more than 
1.5 mm.
Tiles should have a solid or marbled finish. The color of the front surface of the tiles and the tone of their coloring must correspond to the standards.
The water absorption of the tiles should not exceed 16% of the weight of the tiles dried to constant weight.
The dimensions of the tiles are checked with a metal measuring tool or template with an accuracy of 1 mm. The correctness of the right angles of the tiles will be determined with a metal square.
The curvature of the tiles is determined in the following ways: in the case of a concave surface, by measuring the largest gap between the tile surface and the edge of a metal ruler set diagonally to the tile; in the case of a convex surface, by measuring the gap between the surface of the tile and the edge of a metal ruler set diagonally to the tile and resting at one end on a caliber equal to the permissible amount of curvature.
To determine the thermal resistance of the tiles, the selected three tiles are placed in an air bath and gradually heated. Upon reaching a temperature of 100 0 C, the tiles are quickly immersed in water having a temperature of 18-20 0 C, and left in it until completely cooled; then they are taken out and examined. In order to more accurately detect the presence of a counter / roughness /, a few drops of liquid paint or ink are applied to the surface of the tiles and wiped with a soft cloth.
Tiles are considered thermally resistant if, as a result of the test, no cracks, notches, or flakes are found on their glazed surface.
To analyze the uniformity of the color of the front surfaces of square and rectangular tiles, they are placed on the shield close to an area of 1 m 2, and shaped tiles - in a row at least 1 m long. The shield is installed in an upright position in an open place.
The color of the surface of the tiles at a distance of 3 m from the eye of the observer should appear uniform in accordance with the standard.
