Concrete blocks are used when you need to quickly lay a reliable and durable foundation. Large solid panels, for example, are actively used in industrial construction and in the construction of multi-story buildings, but they require lifting equipment. But hollow ones for manual masonry can only support a compact wooden structure.
Advantages of blocks:
- long service life - at least 50-60 years;
- high speed of foundation construction;
- resistance to aggressive environments;
- large selection of standard sizes;
- low cost due to mass production.
Disadvantages include the need to use special equipment during construction. And even if you use light blocks of 20x20x40 cm weighing about 30 kg, you will need at least a hand winch for safe unloading and stacking of building materials. At the same time, the foundation of the panels itself has slightly different properties. When construction time is reduced due to ready-made elements, the cost of the structure itself increases. And labor costs during construction will be higher than when pouring a monolith into formwork. On the other hand, if it is not possible to achieve stable proportions of concrete solution for pouring, or you simply lack experience in this matter, it is better not to risk it and buy a concrete block for the foundation.
Main types
Depending on the application, blocks are usually divided into several types. They are marked with letter designations:
1. F - used in the construction of support columns of a columnar foundation on soft soils.
2. FL - only the base cushion is formed from them, since they have a trapezoid shape with a very wide “heel”. This solution allows a solid structure with reinforcement to take on a significant weight of the building and distribute it over a large area of the supporting soil layer.
3. FBS is the most common type of solid blocks, convenient for the construction of prefabricated strip foundations. For reliable fixation during installation, special cutouts are sometimes made along the edges of such elements. The concrete itself is reinforced with reinforcement bars.
4. BF - in strip bases, but only as a support (bottom row).
5. FBP – lightweight hollow products. They are rarely used for foundations, as they cannot bear significant loads. Their limit is a small frame house made of wood, but for reinforcing walls for pouring a monolithic foundation, their use is quite acceptable.
6. FR - the most powerful foundation blocks made of heavy concrete with steel reinforcement, for capital construction.
7. UDB is a relatively new variety with through square holes.
The letter designation in the marking after the dimensions corresponds to its design: hollow (P), made of heavy concrete (T).
Sometimes special types are distinguished based on their main scope of application:
- For a capital foundation.
These are heavy blocks (FBS, FR, BF) of large size with mounting metal loops for the cable. Thanks to these elements, the products can be picked up by a crane hook and installed in a designated place in the trench.
- For tape.
The significant length of the panels during the construction of a strip base makes it possible to reduce the number of joining seams between its parts, but makes installation difficult if it is not a multiple of the size of the side of the foundation. In this case, you will have to produce additional elements on site from full-size blocks using diamond cutting.
- With openings for communications.
The products have openings for laying engineering systems. It is very difficult to make such selections in concrete manually; the foundation can be seriously damaged as a result.
Standard dimensions
Building blocks are mass-produced at factories for reinforced concrete structures, and their dimensions are regulated by GOST. No one talks about maintaining dimensions to the nearest millimeter, and corners can crumble during storage and transportation. The labeling of each product indicates its parameters in decimeters with rounding. This creates some confusion, since the builders themselves are used to being guided by centimeters. In these units we give the standard sizes of concrete blocks:
Features of using FBS
1. Dimensions.
According to SNiP, the block size can have the following values (cm): 88, 138 or 238. Moreover, there are only two height options - 28 or 58 cm.
Length matters when it is necessary to build a prefabricated strip foundation from concrete panels on soils prone to heaving. At the slightest movement of the ground, long products will act as a lever, increasing the tension in the fastening solution of the joint seams. To prevent the “ribbon” of the base from falling apart into separate parts, you need to additionally buy FL type blocks, which will play the role of a pillow. It is for these reasons that FBS is most often used for columnar types of foundation.
Dimensions are very important, since their correct choice will determine the uniformity of transfer of the weight of the building to the base, and from it to the supporting layers of soil. Therefore, before you buy a batch of reinforced concrete panels, you will need to calculate the loads that the concrete block foundation will have to accept. If the dimensions of the prefabricated elements turn out to be smaller than required, all subsequent operation of the building will be reduced to constant repairs of rickety structures.
2. Characteristics and features.
The strength parameters of FBS may also differ - in the range from B7.5 to B15. The higher the grade of concrete, the stronger the panel itself and the more reliable the foundation made from it. There is one more requirement for the quality of the side surfaces. The type of finish that can be used for the plinth will depend on compliance with one class or another:
1. class A3 – high quality, suitable for painting;
2. class A5 – allowed for finishing with ceramic tiles or gluing with composite panels;
3. classes A6 and A7 - such a surface can only be sheathed using lathing.
Thanks to their solid structure, a foundation made from FBS concrete panels is very reliable and has a number of advantages over other types of reinforced concrete products:
- long service life (60-160 years);
- higher moisture resistance and, as a result, frost resistance;
- the best strength indicators, regardless of the type of load taken.
But do not forget that the price of the foundation will be quite high, and a significant part of it will be transportation costs. Therefore, you need to purchase materials from the nearest reinforced concrete plant or a large supplier.
Price
The price of blocks directly depends on their size and material consumption. Here you need to be tied not so much to the dimensions, but to the weight and volume of concrete used in the production. That is, hollow panels will cost less than solid panels of the same size.
| Dimensions, cm | Average cost, rub/piece |
| 40x20x20 | 52 |
| 60x30x58 | 464 |
| 88x40x58 | 1100 |
| 238x50x58 | 2900 |
Used blocks are also available for sale. Their price is two or even three times lower than new ones, and their performance, in the absence of visible serious damage and corrosion, is no worse.
Concrete is often used in the production of building materials. Among the most popular are blocks from:
- concrete;
- aerated concrete;
- foam concrete;
- sawdust concrete.
Concrete
Concrete blocks are manufactured in factories, making the price of this building material quite affordable. To ensure that the mixture is dense, a vibropress is used. During the production process, the blocks are reinforced and steamed in specially designed chambers for 8 hours. During installation, they must be fastened together with mortar.
Concrete blocks have different purposes: solid blocks are used to build foundations, basements and ground floors, while hollow blocks are used in the construction of building walls. They are a good alternative to brick. At the same time, construction proceeds faster and the cost of constructing the building is reduced.
Durable concrete blocks are made from expanded clay concrete and heavy reinforced concrete. Such blocks are durable and frost-resistant. They have a whole range of sizes and reasonable prices.
Available with parameters 880x400x580 and 2380x600x580 mm, which are used in the construction of multi-story buildings. Their price will be from 700 to 3500 rubles each. When comparing concrete blocks with other building materials that have similar characteristics, it turns out that their cost is quite low.
The use of wall concrete blocks not only speeds up construction work, but also saves mortar. They are characterized by good soundproofing and low thermal conductivity. Due to their small size, they are easy to transport, store and install.
The weight of the blocks depends on their size. with dimensions 200x200x400 mm (one piece replaces 7 bricks) will weigh 31.7 kg. They are intended for hand laying. The lightweight version of the blocks will weigh 28 kg. They cost 50-60 rubles apiece.
Foreman's advice: When stored outdoors, concrete blocks lose their quality and begin to deteriorate. Therefore, it is recommended to store them only in specially designed rooms.
Aerated concrete
Aerated blocks are made from aerated concrete, the main component of which is a finely dispersed silica component, and in second and third place are cement and lime. An aqueous suspension of aluminum powder is used as a gas generator, which reacts chemically with lime. The reaction is accompanied by the release of hydrogen, due to which a large number of pores are formed in the mass for the production of gas blocks.
After the start of the chemical reaction, the mixture is poured into special molds. When aerated concrete hardens, it is cut into aerated blocks of the required size. Then the resulting semi-finished product is sent to an autoclave, where it is treated with water vapor for several hours. If an autoclave was not used in the production of aerated blocks, then the cost of such building material will be lower.
Aerated blocks are a durable building material that can be used for the construction of 5-story houses. Due to its cellular structure, it is light in weight, which means that an appropriate foundation for buildings made of aerated concrete is required. In addition, the cellular structure ensures low thermal conductivity, and due to the even geometry of the gas blocks, the thickness of the seams is minimized. Due to this, the rooms are reliably thermally insulated.
Foreman's advice: the use of aerated blocks will reduce the cost of building a building, since the mass of the entire structure will be significantly less compared to brick.
The cost of aerated blocks depends on their sizes (200x250x625, 375x250x625, 300x250x625 mm and others) and on operational characteristics, such as strength, frost resistance, density, as well as on their purpose: wall aerated blocks will cost more than blocks intended for partitions. Small producers set low prices for aerated concrete. The cost of gas blocks varies from 2100 to 4000 rubles per cubic meter.
Foam concrete
Making foam concrete is easier and simpler than aerated concrete. To do this, sand and cement are poured into an industrial mixer and water is added. Then a foaming agent is added to it, which contains chemicals (therefore, foam concrete cannot be called an environmentally friendly material). Then the mixture is poured into molds and left for 4 hours. At normal air temperatures, foam blocks dry in 2-3 weeks, but faster drying methods can be used - in autoclaves.
The price of foam concrete is lower than the cost of aerated concrete. Foam concrete is characterized by closed porosity. This wall building material can be used in rooms with high humidity, since it does not absorb moisture as quickly as aerated concrete. When purchasing foam blocks, you will need to pay 70-180 rubles per piece, depending on their parameters.
Sawdust concrete
Combines the properties of stone and wood (sawdust). At the same time, it contains up to 90% sawdust, and their parameters do not affect the final strength of the building material. Despite this, this building material is fire-resistant, since the sawdust is concreted and oxygen does not have access to it.
The huge advantage of sawdust concrete is its ease of production and low cost. If desired, you can even prepare sawdust concrete yourself, spending minimal money. This building material is used for low-rise construction. It can be used to construct both residential and non-residential premises.
There are wall and partition blocks made of sawdust concrete of various sizes: 300x200x500, 100x300x500, 100x200x500, 400x400x200 mm and any others. The price can vary from 50 (for a 6-kilogram block) to 160 (for a 24-kilogram block) rubles.
The choice of building material depends on the height of the building, the budget allocated for construction, and the personal preferences of the owner of the house under construction. Of the listed building materials, aerated concrete is the most in demand.
Solid blocks of heavy concrete are an ideal material for constructing strip foundations, basement walls and technical undergrounds, and for constructing retaining walls of low height.
Unfortunately, the mass and dimensions of the most technologically advanced elements on a construction site are so large that they can only be installed using powerful lifting equipment, which significantly limits the possibilities of an individual developer. However, foundation wall blocks - FBS - are actively used on construction sites and occupy a prominent position in the production range of large and small manufacturers of concrete products.
Manufacturing technology and block shape
Wall blocks are simple products made from monolithic concrete. For the production of simple equipment in the form of steel collapsible forms is sufficient. This allows numerous companies that are able to purchase the necessary inexpensive equipment to supply foundation blocks to the market. Quality is influenced by the manufacturer’s integrity and his adherence to technological discipline. It is especially important to correctly prepare the concrete mixture, select aggregate fractions and ensure the parameters of the process of setting and ripening of concrete.
The blocks have the shape of a parallelepiped with a length of 0.9 to 2.4 meters, a height of 0.3 or 0.6 meters and a width of 0.3 to 0.5 meters. The characteristic recess at the ends makes it easier to fill and seal the vertical seam. Heavy concrete of various grades is used for casting. Crushed gravel of optimal granulometric composition is used as a filler, although sometimes you can find products made from crushed stone of sedimentary rocks, for example, limestone or dolomite.
The blocks are not reinforced, since their maximum length prevents too large bending forces when exposed to a distributed load. However, during the molding process they are fitted with steel hinges to facilitate transport and installation.
Dimensions of foundation blocks
An important parameter by which the range of products differs is width. The larger it is, the more massive the wall of the building resting on the block can be, but at the same time the cost of the product increases. Typically, elements with transverse dimensions of 30, 40, 50 and 60 centimeters are produced.
The length of the standard block is 2380 millimeters; this size allows the most economical and technologically advanced construction of foundation walls. For the dressing device, elements with a length of 1180 millimeters are used. Blocks 880 millimeters long are called additional blocks and are intended for filling surfaces whose dimensions are not a multiple of the maximum length. They can be useful when laying out and making technological holes in the foundation wall.
The nominal length of the block differs from its physical size by two centimeters. This allows you to correct possible technological deviations in the dimensions of the product and provides the necessary structural clearance for constructing a vertical seam.
The usual block height is 580 millimeters, which corresponds to a nominal size of 0.6 meters. The difference of two centimeters serves to create a horizontal seam and allows the use of rod reinforcement or mesh in it to create a reinforced belt or screed.
Blocks with a height of 280 millimeters or 0.3 meters of nominal size are also produced. They are designed to adjust the height of the wall and are used in cases where the use of a standard size block is irrational.
Having the necessary equipment, manufacturers can offer additional blocks of other dimensions, for example, 0.6 and 0.4 meters long, with a standard height of 0.6 and 0.3 meters and a width of 0.2 or 0.3 meters. They occupy an intermediate position between foundation and conventional wall concrete blocks.
Concrete blocks for small foundations with a nominal height of 0.15 and 0.2 meters, a width of 0.2 and 0.3 meters, are usually produced in small enterprises using semi-handicraft technology. Designed for manual movement and installation in the design position.
Prices for foundation blocks
Product marking consists of an abbreviation for the product name - FBS, which means “wall (or solid) foundation block” and a set of numbers deciphering its dimensions. The first group indicates the nominal length, the second - the width, the third - the height. The index at the end of the name is used by some suppliers to inform about the composition of the concrete from which the product is made. The letter “t” indicates heavy concrete.
Table of the cost of foundation blocks from one of the manufacturing plants as of the end of 2015:
| Product brand | Volume cubic m | Cost, rub |
|---|---|---|
| FBS 24.3.6.t | 0,406 | 2 113 |
| FBS 24.4.6.t | 0,543 | 2 573 |
| FBS 24.5.6.t | 0,679 | 3 153 |
| FBS 24.6.6.t | 0,815 | 3 758 |
| FBS 12.3.6.t | 0,203 | 1 101 |
| FBS 12.4.6.t | 0,265 | 1 325 |
| FBS 12.5.6.t | 0,331 | 1 592 |
| FBS 12.6.6.t | 0,398 | 1 924 |
| FBS 9.3.6. T | 0,146 | 785 |
| FBS 9.4.6. T | 0,195 | 1 045 |
| FBS 9.5.6. T | 0,244 | 1 147 |
| FBS 9.6.6. T | 0,293 | 1 381 |
| FBS 12.3.3.t | 0,095 | 572 |
| FBS 12.4.3 t | 0,293 | 807 |
| FBS 12.5.3 t | 0,161 | 923 |
| FBS 12.6.3.t | 0,095 | 1 040 |
The cost of a foundation block depends on its dimensions and grade of concrete, which is associated with the consumption of materials and other resources. Relatively high handling and transportation costs can significantly increase the price when purchasing products from a reseller.
Blocks of reduced dimensions, for example 0.4 * 0.2 * 0.2, cost from 60 to 100 rubles per unit, depending on the brand of concrete used and associated costs. The specifics of the production of such products, associated with small enterprises and a wide variety of equipment and technologies used, creates a significant range of prices even within the region.
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.
For the construction of foundations, block materials made from durable and frost-resistant ingredients are often used. This technology is universal, so blocks are laid under the foundation both during the construction of apartment buildings and during the construction of small buildings. Columnar structures are also assembled from them. The main thing is to choose the right blocks, which are made from different materials, which is why they have different names.
This material is based on concrete. Depending on its brand, the size of the reinforcement and the frequency of its installation, the strength characteristics of the block material depend. Concrete block foundation, These are three types of block material:
- FBP - hollow.
- FBS - solid.
- FBV - solid, in which cutouts are made for laying communication networks and filling jumpers.
The first type is the most common. It is made either from heavy concrete or silicate. Second They are also made from heavy concrete or expanded clay concrete. The foundation of expanded clay concrete blocks is already insulated. But it has a minus - compared to models made of heavy concrete, their strength characteristics are lower, so it is recommended to use them for light buildings: a bathhouse, a garage, a barn.
They are lighter than all the others, cheaper, however, it is necessary to note a good indicator of water resistance. Another plus is the cutouts for filling the jumpers. The latter increase the resistance to bending and displacement pressure.
The third type is, in fact, permanent formwork. The installation of foundation blocks of this type is accompanied by additional pouring of concrete into the cavity with preliminary placement of a reinforcing frame inside. The frame consists of vertically installed pins, which are tied to horizontally laid reinforcement. The latter passes through all the voids of the foundation blocks.
Concrete stones come in different sizes and are poured from different types of concrete solutions. Depending on their dimensions, they are used either for heavy buildings or for light ones. The photo below shows the relationship between the sizes of concrete blocks for foundations and their weight and volume.
The table clearly shows that the brand already contains dimensions. This is not the entire classification, because the table does not include materials with small dimensions. For example, FBS 2-2-4, whose weight is 30 kg, which makes it possible to carry out installation without the involvement of heavy equipment.
Concrete blocks are used when you need to quickly lay a reliable and durable foundation.
Foam blocks
Foam block foundations are rarely used. This block material is made using cement, sand and foaming agent.
The latter creates pores inside the structure, which make the stone light and thermally insulating. Unfortunately, such a block design cannot withstand heavy loads, therefore, it is laid for light buildings, one-story dachas. You can assemble them into a strip foundation or a columnar one.
In addition, foam blocks are a hygroscopic material. It absorbs moisture well, so the main requirement for construction is good waterproofing. This applies to all sides of the blocks, as well as gas blocks.
Foam block foundations cannot be constructed in areas with flooding, high groundwater levels, or swampy areas.
Cinder blocks
From the name itself it becomes clear that the filler here is slag, that is, solid waste from various industries.
The cinder blocks themselves are divided into solid and hollow. In this case, the volume of voids can vary between 28-40%.
And the fewer voids, the stronger the product. But the foundation of cinder blocks must be constructed from a solid modification; hollow ones will not withstand the heavy weight of the building. It is necessary to note that there are certain standards regarding the strength of such a foundation. It is prohibited to lay it under a house weighing more than 100 tons.
Construction technology
FBS
Before making a foundation of blocks, it is necessary to carry out a number of preparatory work.
- Marking the foundation.
- Digging trenches.
- Leveling the bottom and walls of trenches.
- Preparing the base of trenches.
You can mark a foundation made of foam blocks or other block materials using twine and pegs. All dimensions of the structure are taken from the building design. Here it is important to accurately observe all dimensional indicators: length, width of the trenches, their depth. Particular attention is paid to the evenness of the walls if the foundation will be assembled at depth. Large curvatures are unacceptable, this can make it difficult to lower the block material into the trench. But, for example, large foundation structures will require lifting mechanisms.
Preparing the trench- this is backfilling the base with a layer of coarse sand or 10-20 cm thick with tamping and watering. The next layer is waterproofing: bitumen, roofing felt, glass insulation, waterproofing films. There are many options, one of them is a layer of concrete screed 7 cm thick.
If FL concrete blocks are used as the base for the house, and this is the base for the main structure, then after installation they are treated with bitumen mastic or ordinary hot bitumen. After which the reinforcement mesh is laid on the prepared base, and the entire surface is filled with concrete mortar.
Before laying the blocks on the foundation, you must wait for the base with the concrete screed to dry thoroughly. Now you can place concrete stones.
- The first row is installed first in the corners of the structure, and then the intermediate areas are filled.
- The seams are filled with mortar: both vertical and horizontal.
- The second row is laid on top of the first with an offset of half the element. That is, the masonry should be in a checkerboard pattern. All masonry of both the first and second rows, as well as subsequent ones, is placed in a horizontal plane.
- When all the reinforced concrete blocks for the foundation are installed, a reinforcing belt is poured on top of them. Why do you need to first assemble the formwork and lay a reinforcing frame made of metal reinforcement into it?
After 8 - 10 days, the formwork is removed and a complete foundation is made from foundation blocks. In this case, roll or coating insulation is used. And the last stage is backfilling, for which it is better to use sand mixed with soil. The backfill must be compacted.
- If the length of all the stacked blocks is not equal to the length of the wall, then you must first make additional elements, which are called seals, before starting construction. These are the same concrete products only of shorter length.
- Openings must be left for laying communication networks. When assembling the foundation, pipes are laid in them, which are filled with concrete mortar on top.
- In places where the external and internal walls meet, the block elements are bandaged.
- After completion of assembly, all blocks are checked by level and plumb. If something sticks out, then it needs to be straightened with a crowbar. If the discrepancy is large, then it is better to disassemble the area and place the element exactly in place.
Expanded clay and cinder blocks
As in the case of FBS construction, expanded clay concrete blocks and cinder blocks are laid on, which is necessarily filled with a reinforcing belt on top. After 28 days, you can begin laying out the foundation blocks.
Since the main dimensions of the stones are 190 x 390 x 188 mm, the block material itself is light in weight. That is, you can do the installation yourself. The laying technology depends on whether the stones will be laid in two rows or in one. If the first option is used, so to speak, a reinforced structure, then the first lower row is laid along the location of the foundation, the second across. In this case, it is better to arrange the blocks of the first row so that they are offset relative to each other by half the product.
Second option- This is ordinary brickwork with a half offset. To fasten the material, a cement-based fastening solution is used. It is laid with a thickness of 1 - 1.5 mm. As usual, installation should begin from the corners of the building, immediately displaying the height of the foundation for the house. After which the intermediate areas are filled. And the last stage is pouring the reinforcing belt on top of the laid expanded clay concrete blocks.
Using exactly the same technology, a type of foundation is assembled from gas silicate blocks. True, they have different dimensions: 250 x 625 x 50 mm, but this in no way affects the assembly sequence and the use of by-products. The only thing you need to pay attention to is This is the glue that holds the block elements together. That is, the first row is laid on cement mortar, and the subsequent ones on adhesive composition, which is called adhesive for gas blocks. The foundation made of aerated concrete blocks is not the most durable, the structure is hygroscopic, therefore, pay attention to enhanced waterproofing.
It is from all of the above materials that they are collected. In principle, the sequence of operations is no different from the construction of a strip structure. Simply, instead of trenches, areas are dug for laying blocks for a columnar foundation. Here it is important to select the dimensions accurately, because the larger the cross-section of the support, the stronger it is.
The blocks themselves are laid crosswise relative to the rows. For example, the first row is two stones laid side by side, the second row is also two elements laid across the first. The next row consists of blocks laid across the stones of the second row.
Advantages and disadvantages
Talking about pros and cons, It must be noted that a foundation made of reinforced concrete blocks is the strongest and most reliable. Weaker structures made of gas silicate and expanded clay. But there is one very important nuance in this matter. Making small foundation blocks with your own hands is not a problem. You can purchase split molds, or rent a machine on which block products are cast. And then, set up the production of a small amount of material. This is a good budget saving.
In addition, building a foundation from blocks is not a very complicated process. The step-by-step instructions described above prove this. Practice shows that the most important thing before building a foundation from blocks is to choose the right material. Of course, large-sized concrete products require the presence of heavy lifting equipment at the construction site. You will have to pay for her services. But if a multi-storey building is being built, then it is better to assemble the foundation from FBS.
The foundation structure for a house made of expanded clay blocks is insulated, aerated concrete blocks are the lightest of all, they can be easily adjusted to any size, which requires a simple saw. It is easiest to build a foundation from them with your own hands due to their small size and light weight.
Conclusion
The types of foundation blocks determine the technology for constructing the overall structure and the degree of complexity of the construction operations being carried out. FBS cannot be installed with your own hands; there are strict requirements for their installation. Even a beginner can assemble block structures made from small stones.
But any foundation must be built taking into account the requirements of SNiP. It specifies which blocks should be used for which foundations. The only thing we note is that you can build a foundation from blocks with your own hands, regardless of the size and weight of the stones. The main thing is to strictly observe the nuances of construction technology.
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