Foundation blocks dimensions normative document. FBS concrete blocks dimensions, weight and markings

Figure 1 — Appearance of FBS blocks

Solid foundation blocks (FBS) are reinforced concrete products, they are part of the foundation that distribute the load on the base.

The blocks provide the ability to perform quick installation and are less susceptible to the influence of external factors compared to a monolithic foundation. Blocks for foundations and walls have:

• strength;
• wear resistance;
• long service life.

To learn in detail about the dimensions and weight of FBS blocks, learn to decipher the markings and understand how foundation blocks are laid, we recommend that you read the publication in full or go to the section that interests you.

FBS are manufactured in the shape of a parallelepiped. For production can be used:

• heavy concrete;
• medium density silicate concrete.

Concrete blocks are not reinforced. Various technologies are used to produce concrete blocks for the foundation, the most common are:

• natural drying (100% strength is achieved on day 28);
• steaming (forced drying to obtain 100% strength in a short time. A block located in the steaming chamber for a day acquires strength from 70% and above).

The most important ingredient in a block is high-quality concrete. The end part of the FBS has grooves that are filled with mortar during installation work.

Figure 2 - Form for filling

The block manufacturing process is as follows:

1. Prepare a concrete mixture using cement, aggregate and water (the solution is mixed using paddles).
2. Load the solution into the block mold (by hand or using ).
3. Compact the solution (used to compact the solution). The concrete compaction process takes a few minutes.
4. Remove the finished blocks after 24 hours (removal occurs earlier if hardening accelerators are used).

To prevent the block from drying out, cover it with plastic wrap and occasionally water it with water. This is necessary for the block to gain strength.

Types and markings

Reinforced concrete products are manufactured in accordance with. They are:

• FBS - solid;
• FBP - hollow;
• FBV - solid with a cutout (designed for passing communications under the ceiling and laying jumpers).

Figure 3 — Structure of block marking symbols

Using an example, consider a block marked FBS-12-Z-6t. When marking, decimeters are used, so the decoding of the marking sounds like this: FBS is a solid block, 1180 mm long, 300 mm wide, 600 mm high, made of heavy concrete.

The letter designations at the end of the brand are deciphered:

• t - heavy concrete;
• n - on porous aggregates (expanded clay concrete);
• c - dense silicate.

In addition to markings, stamps of the manufacturer (including quality control department) are indicated on the block. Pay attention to this when purchasing.

Specifications

Figure 4 - Dimensions of the FBS concrete block

These products must:

1. Made from compressive strength concrete class B7.5 (concrete grade M100) or B12.5 (concrete grade M150). It is possible to produce blocks from concrete with a compressive strength class that differs from that presented in Table 2. For heavy concrete, the indicators are no less than B3.5 (M50) and no more than B15 ().
2. Be frost-resistant (F50).
3. Be waterproof (W2).
4. Be dense (2200 - 2500 kg/m3, heavy concrete).

Table 2 - Technical specifications

Block brand	Concrete class by compressive strength	Consumption of materials		Block weight (average density 2400 kg/m3), t
		Concrete, cubic meters	Steel, kg
FBS24.3.6-T	B7.5	0,406	1,46	0,97
FBS24.4.6-T	B7.5	0,543	1,46	1,30
FBS24.5.6-T	B7.5	0,679	2,36	1,63
FBS24.3.6-T	B7.5	0,815	2,36	1,96
FBS12.4.6-T	B7.5	0,265	1,46	0,64
FBS12.5.6-T	B7.5	0,331	1,46	0,79
FBS12.6.6-T	B7.5	0,398	1,46	0,96
FBS12.4.3-T	B7.5	0,127	0,74	0,31
FBS12.5.3-T	B7.5	0,159	0,74	0,38
FBS12.6.3-T	B7.5	0,191	0,74	0,46
FBS9.3.6-T	B7.5	0,146	0,76	0,35
FBS9.4.6-T	B7.5	0,195	0,76	0,47
FBS9.5.6-T	B7.5	0,244	0,76	0,59
FBS9.6.6-T	B7.5	0,293	1,46	0,70

Step-by-step instructions for laying the foundation

To begin laying concrete blocks for the foundation, dig a pit (trench). To ensure that installation does not cause inconvenience, it is important to find out the dimensions of the FBS blocks (Table 1) and dig a wider trench. The bottom is cleared of rock, irregularities are smoothed out, and the base is filled with sand. In sandy soil it is not advisable to do this work. In order for the laying of a concrete block foundation to be successful, it is necessary to prepare the foundation.

Preparing the base

Figure 5 - Concrete block foundation

For a sand base you will need a wooden beam, 50 - 100 mm in height. Make the sand embankment 200 mm wider than the base of the foundation. After installing the wooden beam (be sure to check the evenness of the surface), moistened sand must be poured inside the frame and compacted.

To increase the area of ​​the base, the initial row is laid wider than the main part (you can use FL foundation slabs or fill the base with a monolithic one).

The gap between laying slabs can reach 700 mm. Next, lay the first row of FBS in such a way that the seams located vertically are above the pillows.

Laying blocks

To begin installing a foundation made of FBS blocks, you need to understand how to lay the blocks. Installation work begins with marking. The stakes are installed according to the drawing, and the thread is pulled along them. To make laying the row easier, first place the blocks at the corners and intersections. Fill the vertical seams with mortar or tamp down as much as possible with earth. The space between the blocks that appears during installation is filled with concrete and leveled until a monolithic insert is formed between the blocks.

The layer of mortar between the top and bottom rows must be at least 15 mm. Vertical seams are tied with a layer of concrete 250 - 600 mm. To strengthen the dressing between the rows, use reinforcement. During laying, do not forget to make a hole for the sewer pipes.

Advice! When laying the foundation, use such types of concrete foundation blocks as FBS24.4.6-T. Their length will allow you to rationally distribute the load on the body of the slab, reduce the number of seams, and save time (select the width and height at your discretion).

Sizes and prices

Depending on the size of FBS blocks, manufacturer and region, the price may vary.

For example, an FBS block with dimensions 880 x 300 x 580 FSK "Tores" in the city of Ufa costs 655 rubles per piece, and the company "Stroykomplekt" in Moscow offers the same product for 843 rubles. per piece

Table 3 - Dimensions and average price per piece in Moscow

FBS 4-3-3	358 rub.
FBS 4-3-6	612 rub.
FBS 6-3-6	863 rub.
FBS 6-4-3	848 rub.
FBS 9-3-6	640 rub.
FBS 9-4-3	831 rub.
FBS 12-6-3	836 rub.
FBS 12-6-6	RUB 1,742
FBS 24-5-3	RUB 2,253
FBS 24-5-5	RUB 2,612

Advice! When purchasing concrete blocks, in addition to the price, ask the seller how many days the block took to gain strength.

Figure 6 - Appearance of a reinforced concrete product for a foundation 200 x 200 x 400

Foundation block 200 x 200 x 400, the price of which is 55 rubles. per piece, is not a type of FBS blocks. It is made of concrete grade M100 and has a frost resistance rating of F50. But due to its small size, experienced builders do not recommend using it at the base of the foundation.

The advantage of foundation blocks 200 x 200 x 400, the price of which is pleasing to the eye, is the ability to lay the foundation in places inaccessible to vehicle access. The weight of one block is in the range of 30 - 35 kg, and for a one-story building (cottage, bathhouse, barn), concrete blocks for a foundation of this size are just right.

Conclusion

FBS blocks are popular among professional builders. There are many varieties of concrete blocks, the main indicator of the size of the FBS is the width (for the construction of the foundation, this indicator is primarily important). Having learned to decipher the FBS brand, you can determine in a matter of seconds what size the concrete block for the foundation is, what concrete it is made of and whether it matches the price.

One of the most common options for building a foundation is the use of concrete blocks.

These structures do not require formwork, and their strength is guaranteed by the factory technology of vibrating and steaming concrete.

When building on soft soils, the blocks are supported on foundation pads - wide prismatic slabs that reduce pressure on the soil.

In addition to the construction of prefabricated foundations, blocks are also used to construct retaining walls, ramps, fences, platforms and overpasses.

Technical production conditions, standard dimensions and strength characteristics are regulated by State Standard No. 13579, issued in 1978. In addition to heavy concrete, this standard allows the use of light silicate mixtures in the production of blocks, provided that their density is not less than 1800 kg per 1 m3.

Types of foundation blocks

The most common type is a solid concrete foundation block, designated by the letters FBS. It is used for installation under external and internal load-bearing walls.

GOST clearly indicates the overall dimensions of these structures:

• With a length of 2.38 meters, the thickness of FBS blocks can be from 30 to 60 cm (steps are 10 cm). The height is the same for everyone - 58 cm;
• Blocks 1.18 meters long are produced in three thicknesses: 40, 50 and 60 cm. Height is available in two standard sizes - 58 and 28 cm;
• Short (additional) blocks. Length 0.88 meters. Thickness is 30, 40, 50, 60 cm. Standard height is 58 cm. Used to avoid chopping a full-size block into pieces, thereby compromising its strength.

The weight of a standard FBS block, depending on the size, can range from 380 to 1960 kg (density 2400 kg/m3).

FBV brand blocks

They are produced to order in small quantities, so they are quite rare on construction sites. The main difference from FBS blocks is the longitudinal cutout used for laying utilities. These are short structures with a standard length (L) of 88 cm. Their width (B) can be 40.50, 60 cm with a height (H) of 58 cm.

For the production of FBV, as well as for FBS, concrete of a grade of at least 100 kg/cm2 (B7.5) and frost resistance of 50 cycles (class F50) is used. For reinforcement, steel of classes A-I and A-III is used.

FBP brand blocks

This is a lightweight type of foundation structures with square voids. They are completely similar in width and height to FBV blocks. They are produced in one length - 238 cm. They are used for the construction of internal walls of basements, as well as foundations for industrial installations.

Produced on the basis of concrete B12.5 (M 150). Frost resistance is 50 freeze-thaw cycles. Reinforcement is performed with steel construction grades - A-I and A-III.

Marking

A characteristic feature of marking all types of foundation blocks is the rounding of overall dimensions to decimeters. Therefore, for example, the GOST designation for a solid block with external dimensions: length 238 cm, thickness (width) 40 cm, height 58 cm will look like this: FBS 24.4.6t (t - heavy concrete). The minimum weight of this design is 260 kg, and the maximum is 2 tons (density 2300 kg/m3).

If the structure is made of lightweight concrete, then after the digital marking the letter “L” or “P” is placed (on the porous aggregate - expanded clay). Minimum weight - 230 kg, maximum - 1.47 tons (density 1800 kg/m3).

If there is a letter “C” after the digital code, this means that silicate concrete was used during casting. The minimum weight of such a block is 250 kg, and the maximum (with a length of 2.38 meters and a width of 60 cm) is 1.63 tons. Density – 2000 kg/m3.

All foundation blocks are equipped with 2 loops (eyes) made of steel wire with a diameter of 12 mm. They are necessary for installation and loading and unloading operations.

Advantages of foundation concrete blocks

• Significant reduction in work duration . When constructing a foundation by pouring concrete into formwork, you have to wait 4 weeks to gain brand strength;
• Standardized sizes . Allows you to accurately calculate the required number of blocks;
• No need to purchase expensive consumables (boards or OSB boards for formwork, additives against freezing and to accelerate the setting of concrete);
• Possibility of selection according to specified characteristics (water resistance, frost resistance, resistance to aggressive liquids);
• Durability (with proper installation and compliance with operating conditions, such structures last more than 100 years).

Approximate prices

Let's briefly look at the sizes and prices of foundation blocks used in civil engineering.

The cost of the smallest (additional) block made of heavy concrete FBS-6-3-6t (length 0.6 m, width 0.3 m) averages 500 rubles/piece.

The same block, but 1.2 meters long (FBS-12-3-6t) will cost from 1,000 rubles. Manufacturers offer full-size blocks 30 cm thick (length 2.4 m) at prices starting from RUB 2,100/piece.

Blocks 40 cm thick and 2.4 meters long (FBS 24-4-6) will cost about 2800 rubles/piece, 1.2 meters long (FBS 12-4-6) about 1400 rubles/piece.

The most popular among buyers are FBS blocks with a width of 60 cm, since this is the thickness of the foundation chosen for residential construction.

The price tags for these structures in the Moscow region look like this:

• FBS-6-6-6t – 1,100 rub./piece;
• FBS-12-6-6t – 2,200 rub./piece;
• FBS-24-6-6t – 4,100 rub./piece;

Hollow blocks (FBP) are much less common in supplier price lists. Average prices for these structures are 10-15 percent higher than for solid blocks. This is explained by the higher labor intensity of filling and reinforcing the mold with voids.

You will not find the price for blocks with cutouts (FBV) in factory catalogs. For their pricing and production, you will have to contact the reinforced concrete plant and make an individual order.

There are often offers on the market for the sale of used blocks. Do not rush to rejoice at their low cost, but rather consult with an experienced builder. He will competently assess the nature and extent of defects and give practical advice regarding the justification of such a purchase.

Features of calculation and installation

As you already said, calculating the number of blocks is quite simple. To do this, you need to determine the volume of the future foundation and divide it by the volume of one block of your choice. As a result, you will receive the required number of designs to order.

There is no need to worry about the number of storeys in the building. The strength of the factory block is quite sufficient to build a five-story house on it.

The condition of the soil is much more critical for such a structure. Here you need to take into account one feature of block foundations - low solidity. Unlike a solid strip foundation, a block foundation has vertical and horizontal seams that weaken it. Therefore, before installing the FBS blocks, a monolithic reinforced concrete belt is poured along the bottom of the trench. It takes on a significant portion of the heaving forces that occur in freezing wet soil.

If the building’s foundation is high (there is a basement), then experts recommend making an armored belt every two rows of blocks.

The ideal foundation for a block foundation is soil composed of coarse sand with a deep aquifer. Since such conditions are very rare, in all other cases the block grillage needs to be reinforced. In addition to using an armored belt, each row of blocks should not be laid dry, but on concrete mortar M 150 with a thickness of at least 3 cm.

Preparing the base

For the base for the blocks, it is enough to make a sand bedding. It plays the role of a leveling layer and its thickness usually does not exceed 15 cm. If construction is carried out on dry sandstones, then the blocks can be placed directly on the ground.

For buildings erected on problematic soils, reinforced concrete foundation pads (FL) are placed under the blocks to increase the supporting area.

Installation of a concrete block foundation

The standards prohibit installing a foundation from FBS blocks if the bottom of the trench is covered with snow or flooded with water. These structures are moved by a crane.

First, blocks are installed at the corners of the foundation and at the junction points of the internal walls. They act as installation beacons. Having checked with a level that the upper planes of all lighthouse blocks coincide, a cord is pulled between them and intermediate structures are placed along it. At points determined by the project, gaps are left between the blocks to allow utility networks to pass through.

Before installation, the blocks are cleaned of dirt and moistened with water. Installation is carried out on concrete mortar with ligation of vertical seams (due to the displacement of rows and the use of additional blocks). Vertical seams are also filled with mortar, compacting it with a bayonet shovel.

Helpful advice: When purchasing foundation blocks, be sure to check with the seller for a certificate of conformity and request a copy for yourself. This document guarantees that the quality of products meets the requirements of the current GOST. It may be needed to substantiate claims and compensate for losses.

There is a widespread belief that a block foundation for a house is used as a way to build the foundation of a building in the shortest possible time, without heavy and expensive preparation, installation of formwork, reinforcement and concreting. This is partly true in cases where the decisive factor was the speed of construction of the building.

Instead of casting a concrete strip, foundation blocks reinforced with steel bars began to be used in industrial, residential and even private housing construction. Thanks to the use of concrete blocks for the foundation, the construction time of the building has decreased significantly.

Advantages and disadvantages of using foundation blocks

In fact, the transition to the construction of foundation systems from blocks was dictated by the need to solve more serious problems than the speed or pace of construction:

• Thanks to new technologies and materials, it has become possible to build relatively heavy brick and panel buildings. Since concrete blocks came out of the walls of reinforced concrete factories with already programmed characteristics and design strength, the block foundation for the house turned out to be much stronger, more stable, gave the same shrinkage and uniform redistribution of the load;
• The construction of a foundation from foundation blocks made it possible to reduce the number of defects associated with violations of the technology for laying reinforcement or pouring and compacting a concrete strip;
• Minimal risk of violating the geometry of the strip foundation, as often happens when the wall of a wooden formwork is squeezed out or due to undesigned shrinkage due to cement laitance going into the ground;
• The number of manual operations and the risk of loss of quality of concrete casting due to violation of optimal concreting conditions and timing are reduced.

The process of concreting a foundation slab or strip always occurs continuously; the time gap between pouring sessions should not exceed four hours. If an automixer with a concrete solution gets stuck on the road, or the weather turns bad at the time of pouring concrete, there is every chance of serious problems with the strength of the foundation. Even concrete material poured exactly according to schedule slowly gains strength, settling and fastening to steel reinforcement. If weather conditions are favorable, the foundation tape will gain strength within a month.

The thicker the concrete casting, the longer you have to wait until the chemical hydration reactions take place throughout the entire thickness of the foundation. Reinforced concrete blocks for the foundation at the time of laying the foundation strip already have a 50-70% safety margin, so there is no reason to fear the formation of cracks or deformations.

Important! The use of concrete foundation blocks allows you to build an MZLF - strip or buried foundation with minimal losses.

The disadvantages of using concrete foundation blocks include the fact that the block method is not suitable for all types of foundations. For example, it is impossible to build a slab version or a pile-grillage type of foundation. Sometimes, for low-rise buildings, foam blocks and pile foundations are used simultaneously, but only as a way of arranging the basement of the building.

It is not necessary to bury the foundation blocks in the ground. In home construction, for example, for light wooden, wood concrete and aerated concrete buildings, a prefabricated strip frame or a columnar foundation made of blocks are widely used.

Blocks for industrial foundation systems

The methodology for constructing foundation systems based on concrete blocks involves the use of two main types of block material - for manual and industrial masonry.

The first type includes industrially manufactured foundation blocks:

• Basic building material, or FBS for short– solid foundation blocks, used for the construction of wall strip foundations;
• Auxiliary concrete foundation blocks FBV on the edges and end surface they have protrusions and grooves, due to which they form technological voids and channels for bypassing communications;
• FBP is a hollow version of block material, used for lightweight block concrete foundations.

It is clear that all of the listed types of block material are used only in industrial construction methods using special measuring tools and handling equipment due to the fact that the weight of the foundation block of the smallest size series 12.4.3t is 310 kg. The heaviest FBS foundation blocks of the 24.6.6t size series weigh almost 3.5t. It is almost impossible to lay a strip foundation from FBS blocks or simply deliver concrete block material to a construction site without the use of special equipment.

In fact, the technology for constructing concrete foundation walls from ready-made reinforced concrete foundation blocks is practically no different from the technique for making brickwork or working with cinder block material. The only difference is that the installation of foundation blocks is much faster than even brickwork, so all kinds of buildings and premises for industrial facilities, warehouses or garages are successfully built from them.

The strength and accuracy of construction largely depends on the correct laying out of the first row, therefore FL foundation slabs must be used for laying FBS blocks. The use of base concrete slabs makes it possible to provide initial preparation, level the horizon and at the same time prevent shrinkage of the heavy foundation block on the sandy cushion of the bottom of the pit.

Materials used for casting concrete foundation blocks

Many private developers have long realized that the use of reinforced concrete foundation blocks is a gold mine in the construction of ordinary cottages and low-rise buildings. Especially if the project includes a huge basement, a basement garage, a boiler room, a cellar and many other interesting things.

The cost of the foundation block of the most popular brands FBS12.5.6t and FBS12.4.6t will be approximately twice as expensive in terms of ready-mixed concrete of an equivalent volume. But taking into account the costs of delivery, formwork, the work of craftsmen and possible problems with technology violations, a foundation made of foundation blocks will cost about the same money, with consistently higher quality.

Therefore, small-sized FBS reinforced concrete blocks are selling like hot cakes. But there is one peculiarity. In addition to size and design, foundation blocks differ in the material used for casting. According to GOST No. 13579-78, three types of concrete mixtures are used:

• Heavy grades of concrete material filled with granite and basalt crushed stone, the density of the casting after setting is at least 2.4 kg/dm 3, and the compressive strength is class B7.5-B12.5;
• Lightweight concrete materials based on expanded clay. The density of the concrete casting is not less than 1.8 kg/dm 3, strength class is not less than B7.5;
• Silica concrete with a density of at least 2 kg/dm 3 and compressive strength class B15.

Based on their intended purpose, foundation blocks are not completely interchangeable; in addition, the cost depends on the material, strength class and accuracy, therefore, when purchasing finished products, you must carefully check the seller’s information with the project data.

For your information! All necessary information about the foundation block is applied with paint through a stencil or by machine to its side surface. Therefore, when purchasing a batch of material, the information on the label must be checked with the data in the delivery note.

The information encoding scheme is shown in the figure.

The service markings of the manufacturer and control marks for installing the blocks into the base of the foundation are also indicated here.

Silicate concrete materials for the production of foundation blocks according to the recipe and manufacturing technology are practically no different from what is used on brick and tile lines. For certain grades of silicate concrete, the addition of high-quality cement is allowed no more than 14% of the volume. The concrete mixture is subjected to hot processing in an autoclave and slow cooling.

After hardening, foundation blocks must be cured until the material reaches a certain percentage of its design strength. It is allowed to produce foundation blocks from heavy grades of concrete with 50% strength gain, expanded clay material - at least 70%, and silicate material - 100% of the design value.

The dimensions of FBS foundation blocks indicated on the markings may differ in height and length by 8 mm and 12 mm, respectively, therefore, when selecting blocks for a row of foundation masonry, a measuring template is usually used. Master foundation workers usually manually measure the material; if the foundation is made of expanded clay concrete blocks and heavy concrete, silicate blocks, as a rule, come with an allowance of a couple of millimeters.

Lightweight foundation blocks

The idea of ​​arranging a concrete block foundation fits very well with the possibilities and needs of home construction. Of course, a heavy two-story brick house made of brick or silicate blocks requires the casting of a full-fledged foundation strip, but such grandiose construction projects do not happen many times in the life of an ordinary developer. Much more often it is necessary to make a foundation for foam blocks, for example, when building a barn, bathhouse or country house on a summer cottage.

Requirements for lightweight foundation blocks

Considering the fact that almost all such buildings are built without the use of specialized equipment, one has to look for foundation blocks for manual masonry. There are not many options for lightweight concrete materials:

• Expanded clay concrete;
• Foam concrete;
• Silica concrete.

Traditionally, the foundation is built from 20x20x40 mm blocks. This is the standard size for wall blocks used for the construction of walls and floors of buildings.

If you set a goal and compare the strength characteristics of the materials listed, you can make sure that the strength values ​​of all the materials listed in the list are quite sufficient for the construction of an MZLF tape. The difficulty lies in the fact that the foundation for an extension made of foam blocks must be both light so that you can build it with your own hands, and at the same time rigid so that the building box does not move apart under its own weight or wind pressure, and most importantly, not absorb water from the soil.

The last condition, oddly enough, is the most difficult to fulfill. If you do not take special measures to protect the concrete material from moisture, then a columnar foundation made of 20x20x40 foam concrete blocks will crumble within a couple of years of operation. Despite the fact that a block of foam concrete can float in water for weeks and remain almost dry, the remaining gas-forming agent inside the porous mass actively absorbs water vapor, which means it leads to waterlogging and frost cracking of the concrete material.

Silica concrete and expanded clay blocks

First of all, it is necessary to clarify that we are not talking about gas silicate wall blocks made from lime and aluminum powder. Such materials in a “raw” form, without external cladding, are prohibited from being used as foundation blocks. As an option, you can use aerated concrete for a foundation for a bathhouse made of foam blocks, but the technique for building an aerated concrete foundation is more reminiscent of a columnar foundation than a strip foundation.

For the classic strip foundation scheme, autoclave materials are used, known to us from the example of sand-lime brick and block, which are widely used for the construction of walls.

The strength and rigidity of silicate and expanded clay concrete mass is at the level of the best brands of ordinary concrete material. Excellent adhesion to masonry mortar makes it possible to build a foundation strip of almost any complexity. But using blocks as a foundation requires special preparation:

• Special additives from ground blast furnace slag are added to the composition of the silicate mass, thanks to which most of the hydrosilicate is converted into an insoluble form that is not afraid of and does not absorb water;
• Carrying out vibration compaction of the molding mass, which allows you to squeeze out residual air and close the pores for the penetration of water vapor and water;
• Treatment of the surface of foundation blocks 20mm by 20mm by 40mm with special deep-penetrating organosilicon preparations.

For your information! Treatment with hydrophobic substances should be carried out only after the construction of the foundation walls.

If you treat the block material before installing the foundation tape, the strength of the masonry on concrete mortar will decrease by at least half due to poor wetting of the surface with cement laitance. As a result, the frost resistance of the material increases by at least an order of magnitude. Laying the foundation base and waterproofing from an adapted material is carried out according to the classical scheme, even without the use of reinforcement and concrete inserts.

Adapted silicate concrete is used to make a huge amount of auxiliary reinforcement, foundations, platforms in industrial and road construction, in transport, and even in the construction of river and sea berths.

Foam concrete materials, is it possible to build a foundation from them?

Wall materials based on foam concrete are divided into two categories - thermal insulation and structural. To understand how suitable foam concrete blocks are for arranging a foundation strip, you need to look at the characteristics given in the table.

Foam concrete grade D1000 has sufficient strength and frost resistance to provide the necessary rigidity of the MZLF. On the other hand, the vapor permeability of foamed concrete is non-zero, which means that a foundation made of foam blocks will require special protection against the penetration of water vapor deep into the foamed concrete material.

Without the use of waterproofing or special protective coatings, you can build a simple foundation of foam blocks for a shed, garage or bathhouse. In this case, the strip frame is not buried in the ground, but is laid out on a bed of sand and gravel mixture. Of course, standard block foundation materials measuring 60x20x20 cm and weighing 30-35 kg are heavy enough to build a foundation from foam blocks with your own hands. More suitable sizes are foundation blocks 20x20x40 cm. Weight of about 20 kg allows an adult to lay a foundation wall without the help of construction equipment.

Relatively recently, composite foam blocks began to be used for the construction of strip foundations. Unlike conventional gas or foam concrete, a standard block is made of several layers. For example, for the manufacture of foundations with basements and basements, a block of three layers is used. The outer part of the foundation block is made of expanded polystyrene foam, the core is filled with cellular foam concrete. The inner surface is lined with PVC or polystyrene. As a result, the basement area receives finishing and waterproofing.

Such foundation blocks have a tongue-and-groove end connection with joint sealing. But still, during assembly, the manufacturer recommends gluing all joints with concrete mortar.

Features of the construction of foam block foundations

The most significant disadvantage of building a foundation from foam blocks is the low rigidity of the material. Foamed concrete, unlike conventional monolithic castings, has increased elasticity and settlement until the final strength is achieved. Even fresh FBS blocks, reinforced with steel rods, after two weeks of exposure are still capable of compacting and deforming under load, so they are used at most for laying the first row of the foundation.

Foam concrete materials have a much higher tendency to elastic deformation, even after final hardening. Therefore, you cannot simply lay out the foundation walls from block material; under the load from the mass of the building box, the foundation will give a significant settlement and, what is worse, the wall masonry will bend inward or outward.

To prevent this from happening, bandages made of a metal corner or channel are placed at the base and head of the shallow belt, which tighten and hold the most loaded areas of the foundation. The middle part of the foundation masonry is reinforced with two or three belts of metal or fiberglass reinforcement.

To ensure the transfer of load from the foam concrete blocks to the laid steel reinforcement, grooves are cut along the concrete masonry every three to four rows, into which the rods are laid. The mounting groove is filled with masonry mortar, and the reinforcing threads at the ends of the foundation walls are heated and stretched by the amount of elastic deformation, approximately 5-7 mm for every 10 meters of length. After the tension system is unfastened, under the action of stretched reinforcement, the masonry of foam blocks goes into a compressed state. As a result, any load on the foundation, whether from the weight of the building frame or frost heaving of the soil, will not lead to the destruction of the foam blocks, extrusion or the formation of cracks.

Technology for constructing foundations from foundation blocks

When assessing the advantages and disadvantages of using foundation blocks, it is worth mentioning the practical side of using a block construction scheme, which practitioners are well aware of. The main value of the block lies in the fact that the construction of the foundation strip can be carried out for as long as desired, without rush jobs and climatic surprises. You can plan the foundation construction work for the entire warm period.

Preparing to lay the foundation block

Regardless of the type and size of the block material, the laying of foundation blocks must be preceded by preparation of the soil and pit. The installation of heavy concrete castings cannot be called absolutely safe, so it is important to draw up step-by-step instructions for a foundation made of FBS blocks.

Foundation concrete blocks must be laid out and adjusted individually, no matter whether this is done with a crane or manually. Therefore, the dimensions of the trench for a shallow foundation scheme or the pit for a buried version will have to be dug wider than the dimensions of the foundation by at least a meter and a half. Increasing the working space is necessary in order to be able to fully carry out waterproofing and insulation of foundation walls.

For a shallow foundation, 50-60 cm deep and two or three rows of silicate blocks high, you can limit yourself to standard trench sizes; this will not affect the quality of the masonry. For other foundation options, before construction begins, a wooden flooring will need to be laid along the contour of the future foundation, on which you can move along the masonry even in bad weather.

At the second stage, it will be necessary to carry out planning and concrete preparation for laying foundation blocks. The base of the belt is carefully leveled horizontally, clay and peaty inclusions are removed as much as possible, and the base of the foundation is covered initially with coarse gravel, then with a mixture of fine gravel screenings and sand. After compacting it three times with a tamper, you need to lay drainage and geotextiles.

Rules for laying heavy blocks

FBS is equally used for the construction of both shallow and wall buried types of foundation. Moreover, the first type is considered more difficult in construction, since the working space around the block masonry is limited, and it is not possible to fully align the position of the blocks using a level or laser level.

When working with foundation blocks weighing 300-400 kg, it is quite difficult to adjust the position of the concrete casting, and this must be done with an accuracy of 3 degrees deviation from the horizontal and vertical axis. Therefore, for MZLF schemes, the first step is to carry out concrete preparation of the foundation base.

A layer of concrete material at least 60-70 mm thick is laid on a compacted cushion of gravel sand and, without cutting the edges of the tape, the surface of the screed is carefully smoothed, trying to achieve a minimum deviation along the horizon. 4-5 hours after pouring, the concrete screed material begins to gain its initial hardness and shrinkage. During this period, it will be necessary to once again clean and level the strip foundation of the foundation. After 2-3 days you can begin laying blocks in the MZLF.

For heavy buildings, FL slabs can be used. After laying the slab base, you need to tie up the reinforcement outlets on the slabs and caulk the joints with resin, bitumen or liquid rubber.

Laying blocks in the foundation strip

After the concrete preparation has been completed, it will be necessary to install beacons and levels along which the planes of each of the laid blocks are aligned. The laying of FDS begins from the corner zones. As a rule, cords are pulled between the corners along the level; for each wall, at least two cords for each row of foundation masonry. Using a pair of cords allows you to adjust the position of the side plane of the block relative to the vertical axis.

The use of nylon cords or thin steel wire is allowed for relatively small foundations; already with a side length of more than seven meters, the stretched beacons sag, and the accuracy of the masonry drops by an order of magnitude. In such conditions, you have to constantly use a level or a two-beam laser level.

After installing the corner blocks, mark the positions of the internal walls and lintels of the basement in a similar way. You can proceed to laying out the walls of the foundation frame.

To fix the foundation blocks, use a thick concrete solution, without gravel and plasticizers. Sometimes a small amount of surfactant is added to the masonry concrete material, for example, washing powder and fluffed asbestos fibers. In this case, the solution adheres better to a vertical surface when sealing gaps between blocks. To avoid shrinkage and cracking, low-modulus grades of cement are used for masonry mortar. Such materials harden for a long time, so the addition of fibers allows the liquid solution to be retained in the cracks without swelling and deformation.

Separately, it is worth mentioning the double-row buried foundations. If the soil under the foundation is quite complex, with a high tendency to heave, the concrete blocks are connected to each other by tying reinforcing bars released at the ends of the castings.

Experts recommend using two rows of blocks for arranging foundation walls, the outer one made of solid monolithic FB, and the inner one made of block silicate concrete. A layer of waterproofing and insulation is laid between two rows of foundation tape. Of course, the masonry is carried out with bandaging of rows and joints so that the seams of adjacent stones do not coincide at a distance of at least 10-15 cm.

Finishing operations

After completing the laying of the foundation strip, you need to clean the walls from any remaining concrete mortar and prime them with a primer. External surfaces must be covered with roll waterproofing in two layers. If the soil is relatively weakly saturated with water, and only surface water is present, then only capillary moisture threatens the walls. In this case, you can get by with coating waterproofing made of bitumen and SBS rubber.

A layer of insulation is glued on top of the waterproofing. Typically, sheets of extruded polystyrene foam or EPS are used, with a thickness of at least 50 mm. Previously, only the outer surfaces of foundation walls were thermally insulated; now experts recommend insulating basements and basements from the inside, especially if the house is heated. This allows you to shift the dew point inside the insulation layer, and since EPS does not absorb water vapor, such a measure makes it possible to avoid condensation on the walls inside the basement.

Any excess moisture for concrete blocks means rapid aging and destruction of the reinforcing steel frame, so any cracks or damage to the concrete material are pre-treated with waterproofing primers before laying the insulation.

The last stage of arranging a foundation strip of blocks consists of filling the spaces between the masonry and the walls of the pit with a dry mixture of clay, ground slag and sand. The top layer of soil removed when digging a pit cannot be used for backfilling the foundation. Most often, sand with loams is selected from the bottom layers of the pit or quarry sands mixed with thin, dry clay are used.

Conclusion

FBS blocks made of silicate concrete are considered the most difficult for arranging foundation strips. Such blocks are already sold with maximum strength and rigidity characteristics. Traditional cement-sand casting, when laid into the wall masonry, remains pliable for a long time and, as the building frame is erected, it shrinks and straightens in the foundation masonry, which allows the load to be equalized along the entire perimeter of the foundation base.

When making a foundation from silicate concrete blocks, there is no such redistributive effect; walls under load can develop cracks and even local destruction. Therefore, it is better to entrust the design of a foundation strip made of silicate blocks to specialists or use it only for the inner row of the basement.

Wall ones are the most popular in the field of modern construction, because they have proven their efficiency and reliability in practice. Therefore, most professionals choose this particular material when constructing any building.

At the same time, experts try to take into account not only the frost resistance, weight, and density of the material, but also the dimensions of the FBS blocks, which are prescribed in the corresponding state standard.

GOST, which determines the dimensions of wall foundation blocks

The main state standard that regulates the dimensions of FBS foundation blocks is GOST 13579-78. It applies to materials made from dense, lightweight and silicate concrete, with a density of at least 1800 kg/m 3 and which are intended for technical basements of buildings and basement walls.

According to it, several types of blocks are distinguished, on which the material parameters (length, height, width) depend.

This document also presents the sizes of FBS blocks, which have their own symbols. And depending on what type of concrete the reinforced concrete structure is made of, the block is assigned a certain marking. It is also determined based on the strength class of the concrete, the mass of the block, the consumption of materials and the brand of the mounting loop.

But dimensions are not the whole list of what this standard regulates. Rules for storing, transporting blocks and assigning labeling are also specified in this document.

Dimensions of wall foundation blocks

The range of this type of blocks consists of 14 standard sizes of products.

At the same time, the main dimensional characteristic for such reinforced concrete structures is their width, and the secondary dimensions of FBS blocks are considered to be length and height.

According to the length, the entire range of materials is divided into 3 standard sizes:

• 2300 mm;
• 1180 mm;
• 880 mm.

The dimensions of foundation blocks according to GOST also take into account the height of the products. According to this parameter, the assortment is divided into 2 groups:

• 280 mm;
• 580 mm.

FBS blocks, the dimensions of which also include width, are divided into products with the following parameters:

• 300 mm;
• 600 mm.

Thus, it turns out that the largest block reaches parameters of 2380x600x580 mm (length, height, width), and the foundation blocks, the sizes of which are the smallest according to GOST, fit into the dimensions 880x300x580 mm.

How to choose the right FBS sizes

In order to correctly determine the parameters of the foundation blocks, it is necessary to initially correctly calculate the area of ​​the base, find out what the masonry will be like and take into account the thickness of the floors and walls being built. The foundation blocks, the dimensions of which you have already determined for yourself, also have special markings.

It is a security code that contains information for the buyer. For example, it says that a reinforced concrete structure has a height of 600 mm, its length is 400 mm, and its width is 600 mm.

If the dimensions of FBS blocks are indicated in the marking in this form FBS 24-6-6 t, this means that the block has a length of 2400 mm, a height and a width of 600 mm each.

In this case, the letter “t” indicates that the structure is made of heavy concrete.

The dimensions of the foundation blocks are also important to consider based on the nature of the soil. For example, for clayey and swelling soils, it is recommended to choose blocks like FBS 24-6-6 or similar ones. The choice of block parameters is also influenced by:

• The depth of their installation.

Taking all factors into account, it is possible to build a well-heated basement, which is not always possible with other types of foundation. By choosing FBS blocks, the dimensions of which absolutely correspond to the future construction, and also taking into account the characteristics of the material itself: its density, frost resistance, durability, you can achieve the construction of an ideal building, which will differ from others in its strength and impeccable appearance.

The dimensions of FBS concrete blocks directly affect the weight of structures. This factor must be taken into account, because for transporting and laying blocks you will definitely need lifting vehicles and equipment.

On our website you can look at the possible ones, evaluate the appearance of such structures and decide for yourself what parameters you will need. After all, first of all, it is necessary to first think through the progress of the work, decide on the type of products, take into account all the nuances of construction, and only after that choose structures based on their dimensions.

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

Types of FBS blocks, their markings

Today, the domestic building materials market offers a wide range of blocks for foundation construction. 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 more than 1800 kN/m 3);
• lightweight high strength concrete(B100);
• high-strength heavy class concrete(M50-M-200).

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

When choosing a material for building a foundation, you must focus on the following criteria:

• expected mechanical loads;
• operating temperature;
• soil moisture level.

The FBS marking contains the dimensional 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 there is a letter indicator:

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

Material Dimensions

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

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. Dimensional parameters are determined by the type of soil and its bearing capabilities. Also important parameters are the thickness of the floors and walls, the total weight of the building, the strength and dimensions of the foundation.

From the above, it is obvious that if the soil’s resistance to loads is low, it is necessary to purchase large-sized FBS blocks for constructing the foundation. In order to create the most durable installation, it is worth using concrete blocks of different dimensional parameters.

Possibility of using building materials

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

Specialized companies provide a truck crane for use, accompanied by an operator, which allows unloading and installation work to be performed at minimal cost.

A prefabricated foundation made of FBS will be an excellent solution when you are short on time. To create a foundation for a house, you only need to qualitatively prepare a plot of land, and when building a traditional strip foundation, you need to perform a number of additional actions: create formwork, build a reinforcement frame, make a mortar, pour it 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 that would make working with concrete mortar impossible.

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

Even novice builders who have no experience working with the material can build a foundation for a residential or country house using trapezoidal FBS blocks. Installing FBS in a trench is not very difficult, which cannot be said about filling the formwork structure with a concrete mixture, which requires strict adherence to the recipe for preparing the solution and the technology for performing the work.

Pros and cons of blocks

FBS concrete foundation blocks are characterized by the following advantages:

• high laying speed;
• excellent load-bearing capacity;
• high density of joining of concrete products;
• durability and reliability;
• presence of mounting grooves (facilitates work with the material);
• versatility (suitable for various types of foundations);
• resistance to temperature changes, 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 in a factory using innovative equipment. All products undergo strict laboratory control to ensure compliance with the stated technical and quality characteristics.

The disadvantages of building block material include the high cost of the sides in comparison with alternative products for constructing a foundation. FBS boards are also characterized by high weight and low heat resistance. When giving preference to this material, you should take into account that the joints between foundation blocks require additional sealing.

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