Construction of houses

Arrangement of reinforced concrete prefabricated foundations

The most common and strongest are reinforced concrete foundations. However, if there is no time to carry out work on pouring the foundation, then their prefabricated version is used. About the features of the device and manufacture of reinforced concrete foundations, we will consider further.

Table of contents:

Advantages and scope of application of precast concrete foundations

The speed of erection of precast concrete foundations makes them very popular, especially in low-rise construction. After installing the base, you do not need to wait a certain period of time, but you can immediately start building the walls.

The use of this type of foundation is possible if the soil and the site have certain properties, namely:

  • in the process of building a house, floor slabs made of reinforced concrete are used;
  • walls are made of high density brick, stone or concrete;
  • the foundation is the basis for the construction of a basement or basement;
  • the soil on the site is heterogeneous.

Installation of strip prefabricated foundations is carried out on all types of soils, except for soil with silty or peaty inclusions. In addition, if the soil has a low level of non-volatile properties, then the installation of a prefabricated foundation is not possible..

Installation of prefabricated foundations is relevant on rocky or sandy soils, groundwater, under which lies at least three meters deep. In this case, the basement will serve its owners for a long time and moisture will not accumulate in it..

In the process of installing the foundation on clay soil, measures are taken to protect it from heaving. However, the basement will still be characterized by dampness if the groundwater is at a low level..

Please note that when choosing a prefabricated foundation as a base for a building, you should take into account many factors and features not only of the soil, but also of the future structure itself. The slightest error can lead to the destruction of the whole house, its deformation, distortion, etc..

Arrangement of reinforced concrete prefabricated foundations

In the process of installing the foundation, blocks of both a hollow nature and monolithic and reinforced inside are used. The first option is relevant if the building is low-rise and is built from lightweight materials such as foam blocks. If the building is massive, then monolithic blocks are used..

The assembly of prefabricated structural elements is carried out using cement mortar. Since the joints that form between the individual blocks will accompany the ingress of water and cold wind into the basement. Vertical waterproofing is used to protect prefabricated foundations.

The main advantages of choosing this type of foundation is the speed of all work and the use of high-quality materials manufactured according to certain standards..

However, to carry out the installation work, specialized equipment is required, which is quite expensive. To eliminate all sorts of shortcomings of prefabricated foundations, the arrangement of special belts is used, making it more monolithic. In the composition of the concrete solution, in this case, special substances are added, the main function of which is to prevent a gap between the blocks and the belt. To increase the bearing capacity of the foundation, it is laid on special reinforced concrete cushions.

In order for concrete structures to have high strength, but low weight, the latest materials are used for their manufacture. After using them, one block weighs about thirty kilograms. In order to reduce the cost of building the base, the technology of arranging a discontinuous prefabricated foundation is used.

For the manufacture of prefabricated foundations, special skills are not required for the installation of formwork, the manufacture of concrete mortar at the construction site. Therefore, all work is carried out quickly and easily. Please note that a pillow placed under the foundation should not allow moisture to pass to it. Therefore, in the process of assembling the prefabricated foundation, it is necessary to ensure a high level of its waterproofing..

Prefabricated reinforced concrete glass-type foundation

The glass version of the foundation is a subspecies of the columnar foundation, however, for the manufacture of the glass foundation, special structures are used – concrete blocks. The upper part of the block is narrowed, and the lower part is widened.

This version of the foundation is used in the process of erecting industrial buildings, basements and machine rooms of nuclear power plants. Among the advantages of glass-type prefabricated reinforced concrete foundations, we note:

  • making the foundation at the factory, and not at the site of construction work;
  • a high level of strength and reliability of a reinforced concrete base, subject to all the rules for its installation;
  • ease of installation, compared to the foundation poured at the construction site;
  • reducing the time for the construction of a structure.

The cost of this kind of foundation is an order of magnitude higher than that of a monolithic one. In addition, specialized equipment will be required for its installation..

For the manufacture of block glass structures, exclusively high-quality concrete is used, which is distinguished by high frost resistance and moisture resistance.

The installation work of this foundation consists of several stages, namely:

1. Preparatory work.

The surface must be carefully leveled, prepared for the installation of blocks.

2. Digging foundation pits for assembling blocks.

At the bottom of the pit, a sand cushion should be provided, which is a so-called shock absorber when transferring the load from the building to the ground. Also, gravel can be used to compact the soil..

3. Installation of blocks.

After careful compaction of the base, the installation process of prefabricated blocks follows. Surface fitting during installation work is carried out manually. To verify the accuracy in checking the horizontality of surfaces, geodetic instruments are used. After installation of each glass, they are waterproofed.

Installation of a glass-type foundation is possible only if the soil on the site has a high level of bearing capacity. Since the main function of this foundation is to evenly distribute the load from the building.

During the installation of glass structures, certain requirements in accordance with GOST should be fulfilled:

  • the use of high quality concrete;
  • installation of structures only after they have gained strength;
  • low moisture absorption;
  • compulsory reinforcement of blocks;
  • the reinforcement should be surrounded by concrete for at least three centimeters;
  • obligatory removal of mounting type hinges.

Installation of glass blocks requires installation of formwork from false reinforcement inclusions.

How to choose blocks for precast concrete foundation

If the region has too cold winters, then you should take care of the increased frost resistance of the blocks even at the stage of their manufacture. In order to increase the resistance of concrete to frost, it contains special additives. If the foundation is constantly exposed to acids, then granite crushed stone must be present in the composition of the concrete for its manufacture..

Depending on the size of precast concrete blocks, they are very diverse. If the building is massive, then large blocks are made for it, for the installation of which specialized equipment is required..

Lightweight private buildings are constructed using small blocks, which are laid by hand. Installation of the base of the prefabricated foundation is approximately thirty percent more expensive than its monolithic version. However, the speed of work is several dozen times higher.

Since the foundation needs moisture resistance, during its installation it is necessary to ensure its double waterproofing. If there are too many joints between the blocks, the foundation needs additional thermal insulation.

If you plan to erect a light frame or wooden building, then blocks with a hollow structure are used for the installation of a prefabricated foundation. In the process of choosing one or another version of the blocks, you should clearly understand their labeling. For example, FSB-3-3-5 indicates that the length of the block is 30 cm, the width is also 30 cm, and the height is half a meter.

In addition, the type of reinforcement used in the manufacture of blocks is an important factor. The degree of block reinforcement directly depends on the load of the building and the material for its manufacture.

Lightweight buildings are made using standard blocks, the length and width of which is twenty centimeters, and the height is forty centimeters. At the same time, limestone crushed stone is replaced by granite, which can significantly reduce the weight of one block, which in this case is up to 32 kg. For the installation of this type of foundation, specialized equipment is not used, all work is carried out manually.

Prefabricated reinforced concrete foundations for reinforced concrete columns

The initial stage of work on a reinforced concrete foundation involves cleaning the base from vegetation, leveling it and making markings. In order to make the markings, you will need a construction cord and steel pegs. In the process of preparing the site, its size should be increased, in relation to the perimeter of the foundation by 200 cm on each side. All contours must be strictly rectangular.

To check the evenness of the markings, pull the cords in a diagonal direction. There should be the same distance from the center of their intersection to each side. This is followed by the process of arranging a trench for a foundation.

If the depth of the foundation is small, then it is quite possible to do the work manually, otherwise, it is better to hire an excavator. Please note that the depth of the trench is controlled at every stage. After digging a pit, a sand and gravel pillow is set up at its bottom. At the same time, the sand must be well compacted; for this, special equipment and water are used. The thickness of this layer is about 100 mm. Next, you should equip another layer of sand, about 150 mm thick. At the same time, the width of this layer is 200-300 mm larger than the width of block structures. After thoroughly compacting the sand, the process of laying waterproofing on it follows. For these purposes, polyethylene film is perfect..

In the process of carrying out the work, you will need:

  • prefabricated blocks;
  • mortar with which the masonry is carried out;
  • waterproofing materials;
  • rebars.

In order to improve the bearing characteristics of the foundation, the blocks are mounted on pre-assembled reinforced concrete cushions. They are laid on a sandy base. By using these elements, it is possible to increase the supporting characteristics and increase the stability of the foundation..

Before starting the installation of the blocks, a small layer of cement mortar should be poured. You should start laying blocks from the corner section. First, the blocks are laid along the perimeter of the foundation, and then along the internal partitions. During the installation work, lifting equipment is used, if the bed layer on the block is damaged, the pillow becomes unsuitable for installation. Next, level the base and install the following blocks. To control the horizontal laying of blocks, a level is used. Reinforcing rods are installed on top of the pillows; welding is used to connect it to each other.

The installation of the blocks begins with the installation of the lighthouse blocks, at the intersection of the walls and in the corner sections. During the installation of the blocks, it is imperative to bandage them. Joints between the previous and next rows are not allowed. If there are irregularities on the surface of the foundation, dismantle the unit and correct this problem..

Pay attention to the top row, it should be absolutely horizontal. In addition, prefabricated blocks must be properly waterproofed. Otherwise, the bearing capacity of the building will decrease. For these purposes, roofing material or polyethylene film is suitable. High-quality waterproofing of the prefabricated foundation will provide a dry basement or basement.

To connect the blocks to each other, cement mortar is used. It is also recommended to insulate the foundation, due to possible heat loss in the area of ​​intersection of blocks.