FBS blocks are a building material intended for the construction of a foundation during the construction of houses. Modern modules are popular among private developers, because their installation requires a minimum investment of time and money (building 1 m 3 of a foundation from this material costs 2,000 rubles cheaper than building a formwork structure and creating a concrete base for a house). When performing work, the main thing is to choose the right type and size of FBS blocks.

Varieties of FBS blocks, their marking

Today, a wide range of blocks for arranging the foundation is presented on the domestic market of building materials. To choose the optimally suitable material, it is worth studying its main varieties, their characteristics and designations.

The quality of products is controlled according to GOST. FBS can be made from the following types of materials:

• silicate concrete / expanded clay concrete(density over 1800 kN/m3);
• high-strength lightweight concrete(B100);
• heavy-duty high-strength concrete(M50-M-200).

Also, in the production of building material, steel reinforcement A1 or A111 is used, which increases the resistance of blocks to mechanical stress and prevents their deformation. High rates of frost resistance are achieved by adding special plasticizers to the concrete mixture.

When choosing a material for the construction of the foundation, it is necessary to focus on the following criteria:

• expected mechanical loads;
• temperature mode of operation;
• soil moisture level.

The FBS marking contains the overall parameters of the concrete product in decimeters. All indicators strictly comply with all requirements of regulatory documentation (GOST 13579-78). Next to the numerical designation is a letter indicator:

• T– heavy class concrete;
• P- expanded clay concrete;
• WITH- silicate concrete of high density.

Material dimensions

According to regulatory documents, there are 15 sizes of FBS blocks. The most significant overall characteristic is the block width.

Parameter	FBS designation
	24.6.6	24.5.6	24.4.6	24.3.6	12.6.6	12.5.6	12.4.6	12.3.6	12.6.3	12.5.3	12.4.3	9.6.6	9.5.6	9.4.6
Width	600	500	400	300	600	500	400	300	600	500	400	600	500	400
Height (mm)	580	580	580	580	580	580	580	580	280	280	280	580	580	580
Length	2300	2380	2380	2380	1180	1180	1180	1180	1180	1180	1180	880	880	880
Weight	1960	1630	1300	970	960	790	640	460	460	390	310	700	590	470

The service life of the structure, the technological process of construction, the time of the "zero cycle" and the price of block modules directly depend on the size of the FBS foundation blocks. Overall parameters are determined by the type of soil and its bearing capacity. Also important parameters are the thickness of floors and walls, the total weight of the building, the strength and dimensions of the foundation.

From the above, it is obvious that with low soil resistance to loads, it is necessary to purchase large-sized FBS blocks for the foundation. In order to create the most durable laying, it is worth using concrete blocks of various dimensions.

Possibilities of using building materials

When deciding to use FBS blocks for building a foundation, it is necessary to take into account that they have impressive dimensions, so you need to prepare a place on the construction site for storing material in advance. In addition, the modules are also heavy, which necessitates the use of special equipment.

Specialized companies provide a truck crane for use, accompanied by an operator, which makes it possible to carry out unloading and installation work at minimal cost.

A prefabricated foundation made of FBS will be an excellent solution when there is a shortage of time. To create a foundation for a house, it is only necessary to qualitatively prepare the land, and when building a traditional strip foundation, you need to perform a number of additional steps: create a formwork, build a reinforcing cage, make a mortar, pour it in and give it time to “settle” and dry.

You can work with foundation blocks at any time of the year. The quality of the foundation will not be affected by rain, frost or other environmental factors in which work with a concrete solution would be impossible.

Savings in the performance of work can be achieved in the following way: lay the blocks not with a continuous, but with an intermittent tape. In this case, the quality of the foundation will not suffer.

Even novice builders who do not have experience with the material can build a foundation for a residential or country house with the help of FBS blocks of a trapezoidal shape. The installation of FBS in a trench is not very difficult, which cannot be said about pouring the formwork structure with concrete mixture, which requires strict adherence to the recipe for preparing the mortar and the technology for performing work.

Pros and cons of blocks

FBS concrete foundation blocks are characterized by the following advantages:

• high laying speed;
• excellent bearing capacity;
• high density of joining of concrete products;
• durability and reliability;
• the presence of mounting grooves (facilitates the work with the material);
• versatility (suitable for foundations of various types);
• resistance to temperature changes, exposure to environmental factors and chemically aggressive environments;
• no need for "shrinkage".

High quality parameters are ensured by strict adherence to technological standards. FBS blocks are manufactured at the factory using innovative equipment. All products undergo strict laboratory control for compliance with the declared technical and quality characteristics.

The disadvantages of building block material include the high cost of the sides in comparison with alternative products for the construction of the foundation. Also, FBS boards are characterized by high weight and low heat resistance. Giving preference to this material, it should be taken into account that the joints between the foundation blocks require additional sealing.

STATE STANDARD OF THE UNION OF THE SSR

CONCRETE BLOCKS FOR BASEMENT WALLS

Specifications

GOST 13579-78

USSR STATE CONSTRUCTION COMMITTEE

Moscow

STATE STANDARD OF THE UNION OF THE SSR

Introduction date 01.01.79

This standard applies to blocks made of heavy concrete, as well as light and dense silicate concrete of medium density not less than 1800 kg / m 3 and intended for walls of basements and technical undergrounds of buildings. Solid blocks are allowed to be used for foundations.

(Changed edition, Rev. No. 1).

1. TYPES AND DESIGN OF UNITS

1.1. Blocks are divided into three types:

FBS - solid;

FBV - solid with a cutout for laying jumpers and passing communications under the ceilings of basements and technical undergrounds;

FBP - hollow (with voids open downwards).

1.2. The shape and dimensions of the blocks must correspond to those indicated on - and in the table. 1.

Table 1

block type	Main block dimensions, mm
	Lengthl	Widthb	Height h

FBS type blocks

A. Blocks 300 mm wide

With appropriate justification, it is allowed to use blocks of concrete of compressive strength classes that differ from those indicated in -. At the same time, in all cases, the concrete compressive strength class should be taken not more than B15 and not less than:

B3.5 - for blocks of heavy and light concrete;

B12.5 - for blocks made of dense silicate concrete.

Note. In the symbol for blocks of concrete of compressive strength classes that differ from those indicated in -, you should enter the appropriate numerical index before the letter characterizing the type of concrete.

1.5. The location of the mounting loops in the blocks must correspond to that indicated on -. The designs of the mounting loops are given in.

It is allowed to install mounting loops in blocks of the FBS type 1180 and 2380 mm long at a distance of 300 mm from the ends of the block and flush with its upper plane.

1.3 - 1.5.

Block brand	Compressive strength class of concrete	Mounting loop		Consumption of materials		Block weight (reference), t
		brand	Quantity	Concrete, m 3	Steel, kg

Note. The mass of blocks is given for heavy concrete of average density of 2400 kg/m 3 .

2.7. The value of the normalized tempering strength of concrete blocks (as a percentage of the compressive strength class) should be taken equal to:

50 - for heavy concrete and light concrete of class B12.5 and above;

70 - for heavy concrete class B10 and below;

80 - for lightweight concrete class B10 and below;

100 - for dense silicate concrete.

When supplying blocks in the cold season, it is allowed to increase the normalized tempering strength of concrete, but not more than the following values ​​(as a percentage of the compressive strength class):

70 - for concrete class B12.5 and above;

90 - for concrete class B10 and below.

The value of the normalized tempering strength of concrete should be taken according to the design documentation for a specific building or structure in accordance with the requirements of GOST 13015.0.

The supply of blocks with a tempering strength of concrete below the strength corresponding to its compressive strength class is carried out on the condition that the manufacturer guarantees that the concrete blocks will achieve the required strength at the design age, determined by the results of testing control samples made from concrete mix of the working composition and stored under conditions according to GOST 18105.

2.5 - 2.7. (Revised edition, Rev. No. 1).

2.8. When blocks are released to the consumer, the moisture content of lightweight concrete should not exceed 12%.

(Revised edition, Rev. No. 1).

2.9. Mounting loops of the blocks should be made of rod hot-rolled reinforcement of smooth class A-I grades Vst3ps2 and Vst3sp2 or periodic profile Ac-II, grade 10GT according to GOST 5781.

Reinforcement made of VSt3ps2 grade steel is not allowed to be used for mounting loops intended for lifting and mounting blocks at temperatures below minus 40 ° C.

2.10. Deviations of the design dimensions of blocks should not exceed, mm:

length 13

in width and height 8

according to the dimensions of the cutouts 5

2.11. The deviation from the straightness of the profile of the block surfaces should not exceed 3 mm over the entire length and width of the block.

(Changed edition).

2.12. The following categories of concrete surface of blocks are established:

A3 - front, intended for coloring;

A5 - front, intended for finishing with ceramic tiles, laid on a layer of mortar;

A6 - front, non-detachable;

A7 - non-frontal, not visible in operating conditions.

Requirements for the quality of block surfaces - according to GOST 13015.0.

(Revised edition, Rev. No. 1).

2.13. (Deleted, Rev. No. 1).

2.14. In the concrete of blocks accepted in accordance with Sec. 3, cracks are not allowed, with the exception of local surface shrinkage cracks, the width of which should not exceed 0.1 mm in blocks of heavy and dense silicate concrete and 0.2 mm in blocks of lightweight concrete.

(Revised edition, Rev. No. 1).

2.15. Mounting loops must be cleared of concrete overlays.

3. ACCEPTANCE

3.1. Blocks should be accepted in batches in accordance with the requirements of GOST 13015.1 and this standard.

3.2. Acceptance of blocks in terms of frost resistance and water resistance of concrete, release moisture of lightweight concrete, as well as in terms of water absorption of concrete blocks intended for operation in an environment with an aggressive degree of impact, should be made based on the results of periodic tests.

3.3. Tests of concrete for water resistance and water absorption of blocks to which these requirements are imposed should be carried out at least once every 3 months.

3.4. Release humidity of lightweight concrete should be controlled at least once a month based on the results of testing samples taken from three finished blocks.

The assessment of the actual release humidity should be carried out based on the results of checking each controlled block according to the average value of the moisture content of the samples taken from it.

3.5. Acceptance of blocks in terms of concrete strength (concrete class in terms of compressive strength and tempering strength), compliance of mounting loops with the requirements of this standard, accuracy of geometric parameters, technological crack opening width and concrete surface category of blocks should be carried out according to the results of acceptance tests.

3.6. Acceptance of blocks in terms of the accuracy of geometric parameters, the category of concrete surface and the width of the opening of technological cracks should be carried out based on the results of selective control.

3.7. Acceptance of blocks by the presence of mounting loops, the correctness of marking and signs should be carried out by continuous control with the rejection of blocks that have defects according to the indicated indicators.

Sec. 3. (Revised edition, Rev. No. 1).

4. CONTROL AND TEST METHODS

4.1. The compressive strength of concrete should be determined in accordance with GOST 10180 on a series of samples made from concrete mix of the working composition and stored under the conditions established by GOST 18105.

When testing blocks by non-destructive methods, the actual compressive strength of concrete should be determined by the ultrasonic method in accordance with GOST 17624 or mechanical action devices in accordance with GOST 22690, as well as other methods provided for by the standards for concrete testing methods.

(Revised edition, Rev. No. 1).

4.2. (Deleted, Rev. No. 1).

4.3. The frost resistance grade of concrete should be determined according to GOST 10060.

4.4. The water resistance of concrete blocks should be determined in accordance with GOST 12730.0 and GOST 12730.5 on a series of samples made from concrete mix of the working composition.

(Revised edition, Rev. No. 1).

4.4.1. (Deleted, Rev. No. 1).

4.5. The water absorption of concrete blocks intended for use under conditions of exposure to an aggressive environment should be determined in accordance with the requirements of GOST 12730.0 and GOST 12730.3 on a series of samples made from concrete mix of the working composition.

(Revised edition, Rev. No. 1).

4.6. (Deleted, Rev. No. 1).

4.7. The moisture content of lightweight concrete should be determined in accordance with GOST 12730.0 and GOST 12730.2 by testing samples taken from finished blocks.

At least two samples should be taken from each block.

It is allowed to determine the moisture content of concrete blocks by the dielcometric method in accordance with GOST 21718.

(Revised edition, Rev. No. 1).

Foundation building blocks, or more simply FBS, are the most common type of reinforced concrete products in our time. Ready-made blocks are easier and cheaper to lay in houses than to fill with solid concrete and wait until it hardens. The FBS block is used for the construction of basement walls and.

The task of FBS blocks is to withstand huge loads, holding the weight of the entire building. When choosing foundation blocks, one should take into account their ability to, water resistance and frost resistance.

According to GOST 13579-78, foundation blocks are divided into three types - FBS, FBV and FBP. They are made from silicate, or from heavy.

brand FBP- hollow foundation block. They have one standard length of 2.4 m, but may differ in height and width. Lightweight blocks are made leaving vertically closed or horizontal voids.

In addition to GOST, there are several more markings. For reference, here is a short list of zero cycle element designs:

Now let's try to figure out which concrete is most often used. - these are, first of all, building structures that work mainly in compression (with the exception of foundation pillows). Therefore, there is practically no need to use high. Let's turn to GOST 13579-78: the maximum compressive strength class will be B15 or concrete marked M-200. The minimum class for expanded clay products or heavy concrete is B3.5 or marking M-50. And the minimum class for products made of silicate concrete is B12.5 or grade M-150.

In most cases, weighted cement concrete B7.5 is selected for the foundation for blocks of the FBV and FBS types. For weaker FBPs, a much stronger material of the B12.5 type is needed.

Blocks made of heavy with reinforcement are called foundation pillows, abbreviated as FL. They are used in the construction of strip foundations for residential high-rise buildings. Due to the high load that FL blocks can withstand, they are subject to high requirements for dimensional accuracy and material quality during manufacture. Reinforced concrete foundation blocks are able to withstand seismic activity of 9 points, have high resistance to temperature fluctuations and corrosion.

The size of the foundation blocks FL is determined by GOST 13580-85.

Table of sizes of FBS blocks

Prefabricated strip foundation remains a fairly common type of supporting part of the house. Prefabricated blocks allow you to reduce construction time, since there is no need to wait a month for the concrete to harden. Before purchasing products, it is worth understanding what types of foundation blocks are and what each of them is intended for.

According to GOST 13579-78, concrete products for the construction of basement and underground walls are made of three types:

All types can be made of heavy, silicate concrete or expanded clay concrete, the density of which is not lower than 1800 kg/m3.

FBS marking means solid products. Most often they are made of cement concrete. The strength characteristics of such products are higher compared to the rest. Only this type according to GOST can be used for foundations for buildings.

Drawings of the series 1.116-1 "Concrete blocks for basement walls", which are used in the manufacture of elements, do not require reinforcement. According to this document, metal is used only for the manufacture of mounting loops. But sometimes at factories in the production of FBS blocks of large sizes (width and length), rods of longitudinal reinforcement are laid.

FBS - a; FBP - b

Blocks brand FBV differ from solid ones in that they have a longitudinal cutout designed for laying engineering communications. They are manufactured according to the same series as FBS (GOST is also general). They are used in construction very rarely, so such products cannot be found in factory catalogs. If necessary, you need to make an individual order.

Brand FBP are hollow concrete products. They are manufactured according to the same series 1.116-1 and GOST 13579-78. Lightweight blocks have square voids open down. Available in different widths and heights, but only in one length 2.4 m (2380 mm). FBP elements are suitable for building internal basement walls or as foundations for industrial equipment.

What kind of concrete is used

A strip foundation is a building structure that works primarily in compression (with the exception of foundation pads). There is no need to apply high grades and classes of concrete. According to GOST 13579-78:

• maximum compressive strength class B15 (or brand M200);
• the minimum class for products made of expanded clay concrete or heavy concrete B3.5 (or grade M50);
• the minimum class for elements made of silicate concrete is B12.5 (grade M150).

Most often, heavy cement concrete B7.5 is used for foundations for blocks according to the FBS and FBV series. For weakened FBPs, a stronger material B12.5 is used.

Prefabricated strip foundation.

Marking

Before buying, it is important to study the dimensions of the blocks, their characteristics and what concrete they are made of. All this information is contained in the label. A detailed transcript can be seen in GOST 13579-78 in paragraph 1.3. The structure looks like this:

FBS.XX.X.X - X.

Some factories use a dash instead of a dot to separate numbers. But the decoding does not change from this.

In the first position there is a number indicating the length of the block made according to the series. The value is indicated in decimeters rounded. To calculate the exact value, you need to subtract 20 mm (2 cm, 0.2 dm).

Advice! Also subtract 2 cm to find the exact height. This value falls on the seam between adjacent products. When constructing foundation sweeps, it is not taken into account (they take rounded dimensions, for example, a height of 600 mm, a length of 2400 mm, etc.).

The number in the second position shows the exact width of the product, and in the third position the rounded height. All dimensions are given in decimetres. The last position indicates the letter indicating the type of concrete used for the manufacture (T, P or C).

Designation examples:

• FBS.12.6.3-T - made of heavy cement concrete, having exact dimensions of 1180x600x280 mm (length, width and height, respectively);
• FBS.9.4.6-P - expanded clay concrete (material on porous aggregates) 880x400x580 mm;
• FBS.24.5.6-S - made of dense silicate concrete 2380x500x580 mm.

Dimensions of typical products.

Marking according to the series and GOST will be needed when ordering products at the factory. It is important not to make a mistake with this question and not confuse the sizes (the easiest way is to swap the height and width).

Advice! To prevent mistakes, it is worth remembering that foundation blocks are only available in heights of 600 and 300 mm (rounded), but there are more width options.

The range of sizes of foundation blocks by series

Most often, several standard sizes of FBS are used in the construction of foundations. In order to accurately determine how many products will have to be purchased, a special drawing (sweep) is made, where the products are laid out in detail along the entire length and height of the basement wall, taking into account the dressing between the blocks (the minimum is 25 cm).

In the table below you can see the dimensions of the blocks made according to the series (typical) regardless of what material is used.

Marking	Height, mm	Width, mm	Weight of one product, t
Length 2400 (2380) mm
FBS.24.6.6	600 (580)	600	1,96
FBS.24.5.6		500	1,63
FBS.24.4.6		400	1,3
FBS.24.3.6		300	0,97
Length 1200 (1180) mm
FBS.12.6.6	600 (580)	600	0,96
FBS.12.5.6		500	0,79
FBS.12.4.6		400	0,64
FBS.12.3.6		300	0,46
FBS.12.6.3	300 (280)	600	0,46
FBS.12.5.3		500	0,39
FBS.12.4.3		400	0,31
Length 900 (880) mm
FBS.9.6.6	600 (580)	600	0,7
FBS.9.5.6		500	0,59
FBS.9.4.6		400	0,47
FBS.9.3.6		300	0,35

The table shows the mass for products made of heavy concrete with a density of 2400 kg/m3.

The width of the foundation block is selected depending on the thickness of the walls of the building. Small overhangs of elevated structures are allowed. For example, for a brick, the protrusion should not exceed 4 cm on each side. This allows using foundation blocks 600 mm wide for 640 mm walls, 500 mm wide for 510 mm walls.

The length of the foundation block is selected according to the sweep. Place products of different sizes so that the wall folds evenly, without strong protrusions. If it is not possible to lay blocks of standard size, it is allowed to split the elements along the length.

Most often, products with a height of 600 mm are used. Blocks of 300 mm are used as additional ones, if necessary, make holes in the strip foundation (air ducts, inputs and outputs of networks).