Clay and hollow bricks


The brick has the shape of a rectangular parallelepiped with smooth edges and straight edges and corners; size 250x120x65 or 250x120x88 mm. For bricks with a thickness of 88 mm, round or slotted technological voids are required.

For the production of building bricks, fusible clays are usually used, containing 50 – 75% silicon dioxide, and loams with or without depleted and burnout additives..

The volumetric weight of an ordinary clay brick is in the range of 1700 – 1900 kg / cubic meter, and the thermal conductivity coefficient is 0.65 – 0.7 kcal / m o h o deg. Depending on the value of the ultimate strength in compression, the brick is divided into grades 75, 100, 125, 150 and 200.

The brick, dried to constant weight, must have a water absorption of at least 8%. This requirement assumes some porosity of the brick, since otherwise it will have increased thermal conductivity and, in addition, the mortar will adhere poorly to it. Frost resistance of bricks – at least 15 cycles of alternating freezing and thawing. The brick must be properly fired. The firing temperature for ordinary brick clays is on average 900 – 1100’C.

Unburned brick (scarlet) has insufficient strength, low water resistance and frost resistance, and burnt (iron ore) has an increased volumetric weight, high density and strength, a relatively high thermal conductivity and, as a rule, a distorted shape. The brick must meet the requirements of the standard in terms of appearance. This is established by examining and measuring a certain number of bricks from each batch according to the following criteria: deviation from the established dimensions (in length ± 6, in width ± 4, in thickness ± 3 mm), curvature (in bed up to 4 mm, in a spoon up to 5 mm), chipped corners and edges (no more than two on each brick no more than 15 mm in size), the presence of through cracks passing across the brick (no more than one 40 mm long inclusive).

Brick is used for laying external and internal walls, making wall blocks and panels, as well as for laying furnaces and chimneys only in those areas where the temperature does not exceed the temperature of brick firing.


The outer walls of buildings made of ordinary clay bricks are usually relatively thick (2 – 2.5 bricks) for thermal protection reasons. Very often, such walls have excessive strength that is not fully used. In addition, the large weight of such walls creates a significant load on the foundation. Therefore, they tend to replace solid bricks with other, less heat-conducting products, which are often called effective. These include porous, hollow and porous hollow bricks and hollow ceramic stones. These products have a lower volumetric weight and a lower coefficient of thermal conductivity than solid bricks, but they have sufficient strength. In addition, some of these products are larger than ordinary bricks..

The use of effective products makes it possible to reduce the consumption of wall materials by 20-30% (compared to solid bricks), reduce the weight of buildings and reduce the cost of construction (for example, the cost of 1 sq. M. Of a 52 cm-thick wall made of effective clay seven-slot brick by 20-25% below the cost of a 64 cm thick wall made of solid clay brick). In addition, in the production of these materials, raw materials, fuel, electricity are saved and the production time of products is reduced..

Hollow building bricks made with through (perforated) or blind (five-walled) voids located perpendicular to the beds. Low-melting clays or clay-tripoli mixtures with or without burn-out additives are used as raw materials for its production. Single brick has dimensions of 250x120x65 or 250x120x88 mm, and one and a half – 250x120x103 mm.
Depending on the ultimate strength in compression and bending along the gross section (without deducting the area of ​​the holes), it is produced in four grades – 75, 100, 125, 150. With a brick height of 88 and 103 mm, the compressive strength is taken with a factor of 1.2.

By volumetric weight (gross), hollow brick is divided into two classes: B – with a volumetric weight of up to 1300 kg / cubic meter, C – with a volumetric weight of 1300 – 1450 kg / cubic meter. For five-walled bricks, the gross volumetric weight should not exceed 1500 kg / m3. Water absorption of hollow bricks is not less than 6% (by weight), and frost resistance is not less than 15 cycles.

Vertical holes are not formed in the masonry of five-walled bricks, and the existing closed voids improve the heat-shielding properties of the masonry. Perforated and five-walled bricks are used along with ordinary bricks. It is not allowed to use perforated bricks for laying foundations and underground parts of walls, furnaces and smoke channels.

Lightweight construction brick has the same shape and size as an ordinary one. It is made from clays or from clays and tripoli (diatomites) with burnout additives. By volumetric weight, it is divided into three classes – A, B, C (volumetric weight from 700 to 1400 kg / m3), each of which corresponds to certain brands (from 35 to 100). Its frost resistance must be at least 10 cycles.

Lightweight bricks are used for masonry walls of low-rise buildings, the upper floors of multi-storey buildings. It is not allowed to use this brick for laying foundations, plinths below the waterproofing layer, stoves and smoke channels. The relatively low weight and low thermal conductivity of lightweight bricks make it possible to lighten the weight of the structure, since it is possible to reduce the thickness of the walls and the number of bricks in the masonry.

Hollow wall stones made in the form of a rectangular parallelepiped with straight edges and smooth or corrugated surfaces, with through or closed voids. The dimensions of the stones are larger than those of bricks (length 250 – 290, width 120 – 190, thickness 138 – 288 mm), which contributes to an increase in labor productivity when laying walls and a decrease in the number of joints. Bulk gross weight of stones is not more than 1400 kg / cubic meter. Water absorption of stones is allowed at least 6%, frost resistance – at least 15 cycles.

Stones of grades 75, 100, 125, 150 kg / sq. Cm are distinguished by strength (gross cross-section). The brand is determined by placing the stone in the press according to the position of the stone in the masonry.

Hollow stones are used for masonry of load-bearing walls, walls of frame buildings, internal load-bearing walls and partitions.
Due to the lower thermal conductivity and lighter weight in comparison with ordinary bricks, the thickness of the wall made of hollow stones is reduced by 20 – 25%, and the weight of 1 m of the wall is reduced by almost 50%.

Rate article
Tips on any topic from experts
Add comment

By clicking the "Submit comment" button, I consent to the processing of personal data and accept privacy policy