The foundation of the house takes on all the load that the erected structure has on it along with all communications, facing materials and other structural elements. There are many types of foundation, and each has its own functional and operational characteristics. The so-called prefabricated base for a house can be built from foundation wall blocks, the main thing is to find material of a high class of strength and excellent quality.
FBS - these are products with a large weight, made of silicate and expanded clay concrete. Scope of application - construction of foundations, walls of plinths and basements, walls, bridges, flyovers, ramps.
This material helps out perfectly if the task is to quickly install structures of an underground type. The level of strength of the products is quite high, but somewhat inferior to the blocks of reinforced concrete foundation.
The material is used in the construction of low-rise buildings, as well as high-rise buildings.
The quality of FBS is determined by their technical characteristics. The density of the block must be at least 1800 kg / m³, without internal cavities.
If you see the letter designation "C" on the product, you should know that these are the foundation solid blocks of FBS.
The marking with the letter "P" indicates that this product has internal voids, and the letter "B "Says that the blocks are made with recesses for laying sewer systems.
Foundation wall blocks are produced with reinforcing reinforcement to order, and without reinforcement. The latter type is the most common. Reinforced blocks have an increased level of strength.
for the construction of walls, they perform the function of permanent formwork. Reinforcement is immersed in the cavity of the block and poured with a solution of concrete. FBV are the same FBS, only with a single difference in the form of cutouts for pipes of communication systems.
GOST of wall foundation blocks No. 13579-78 determines that the above types of concrete blocks can be used for the construction of basement walls and other underground structures, and specifically FBS is suitable for the construction of a foundation .
.. The strength and duration of using the finished base of the house depends primarily on the competent laying of the material.
In the production of concrete blocks, special vibrating tables are used to compact the mass. Vibrating devices immersed to a certain depth are also suitable for this purpose.
To make the block of the dimensions set by the standard, special shapes are used. It is very important to create the correct geometry of the block, otherwise, the products cannot ensure the density and evenness of the masonry. As a result of such negligence, too large gaps between the blocks will allow moisture to pass through, and this will entail the destruction of the structure in the future.
In order for the concrete foundation block to set faster and harden, the finished product is treated with steam.This technology provides a set of strength characteristics up to 70% in 24 hours.
This is a significant difference compared to the natural drying method, which stretches for up to a week. Steam technology does not negatively affect product quality.
According to the GOST regulations, concrete blocks are produced in the following sizes:
As a material for the production of FBS blocks, silicate concrete (density class 2000 kg / m³) or expanded clay composition (density class 1800 kg / m³) concrete is used.
The strength class of the concrete solution should be:
Frost resistance of FBS should be at the level of 50 cycles, and water resistance at level W 2.
Letter designations on concrete products indicate the type of cement:
Note. For clarity, consider an example: FBS-24-4-6 P is a block of their concrete with dimensions of 2380 x 400 580 mm, made of expanded clay.
Given the large dimensions of the blocks, as well as their weight, the average weight is 260 kg, when building the foundation for a house, it is necessary to use the services of special equipment. For the construction of residential buildings, FBS is used, having a thickness of 600 mm, the mass of which is 1960 kg.
Note. Before purchasing concrete blocks, check the product for compliance with the declared weight and dimensions.
If the indicators point in the direction of decreasing weight, and the letter T is on the marking, this means that you are offered hollow blocks with a low level of strength.
Also, you can protect yourself by asking the seller to provide certificates of product quality. Experts advise buying FBS from trusted manufacturers.
Very often, a self-made manufacturing method cannot guarantee a high-quality output. The reason for this is the violation of the technological process and the use of low-quality materials.
Foundation wall blocks are equipped with mounting slings during manufacturing, which are mounted in the upper part of the product. To create loops, hot-rolled steel reinforcement or a profile with a section changing along the entire length is used. If there is a need, you can place an order for blocks without slings, which is also permissible by the standard.
FBS is produced with the possibility of surface finishing, as well as without it. This fully depends on the type of material. In order for the master to have the opportunity to carry out finishing work, the concrete product must have a smooth, even surface, without defects in the form of chips. There may be shallow cracks up to 0.1 mm for heavy and silicate concrete, and within 0.
2 mm for expanded clay material.
The peculiarity of FBS blocks is that they are almost indestructible over time, so they can be reuse. Such material will be a good option for those who want to save a little money on building a house. Their technical characteristics remain the same, so there is no need to fear for the quality of the result. New products and second-hand FBS, it is advisable to buy from well-known companies, for example, at factories for the production of reinforced concrete products.
There are situations when the use of FBS blocks is more than justified.
Of course, FBS blocks, like any other material, have their drawbacks, but they do not relate to the technical features of the product.
But, for someone, this drawback may become significant - the high cost of transportation and installation of concrete products.
Block foundation is best erected on rocky or sandy soil. In such areas, belt-type foundations are often built. If the soil on which the construction of the house is planned is shaky, then the installation of the blocks is done according to the following principle: a belt of reinforcement is laid every 2 rows, in addition, reinforcement is made at the bottom of the pit under the foundation. Also, you need to make a pillow of sand and gravel before starting work.
To do this, sand is poured with a first layer of 15 cm, moistened with water, and gravel is poured to a level of 10 cm.At the end, a sand layer is also formed and tamped.
On soils characterized by density and stability, it is possible to build an intermittent type foundation. This method of stacking makes it possible to reduce the number of blocks required and, accordingly, reduce costs.This method of forming the foundation differs in that there are gaps between the blocks, which are subsequently covered with soil and rammed.
Important! A foundation of this type can be erected on soil that has good mechanics for withstanding the load exerted by the constructed building.
Before you start laying the foundation, you need to make calculations. The distance between the blocks with an intermittent type of laying should not be more than 70 cm. Such a base is suitable for small houses, no more than 2 floors, built of hollow materials.
On unsteady soils, special cushion blocks are used for laying the first row, the width of which is larger than that of FBS.
This allows you to increase the base of the foundation under the house. Then concrete blocks are laid on the base, so that the seams between the products fall on the blocks of the first row.
Builders insist on buying blocks with a longer length, motivating this by the fact that in the process of laying the material, fewer seams will be obtained. This, in turn, will ensure the reliability and strength of the structure.
Most often, for laying the foundation, FMEs are purchased with a height of 580 mm, which is explained by the convenience of their use.
The lower the degree of bearing capacity of the soil, the larger the blocks should be. On clay soils, the foundations of their reinforced concrete blocks are erected with FBS parameters 24-6-6, on sandy soils - 12-6-6, they are shorter than the previous ones. The optimal number of blocks for the length of one wall is 4 - 5 pieces, taking this into account, the length of the foundation wall products is selected.
Note. The degree of strength of FBS allows building thicker walls than the foundation of the house.
The wall can extend beyond the base by 6 cm on each side or 10 cm on one side.
The cost of the FBS directly depends on the dimensions of the product. Additional blocks of small sizes cost about 500 rubles, and heavy ones - within 4000 rubles. Blocks made with quick stripping cost less than those that are cast in special molds. In addition, the price of steamed FBS is higher than that of products that undergo a natural drying process.
As mentioned at the very beginning, this production technology does not in any way affect the quality of the finished product. In this case, the buyer pays for the speed of the order. But, professionals say that blocks that gain strength and strength over a period of 28 days have better technical characteristics.
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