Concrete preparation for the foundation: what is needed,

Before the construction of the foundation, in addition to preliminary calculations, it is necessary to prepare the construction site in a special way. In particular, the important point is the laying of the pillow. The so-called concrete preparation for the foundation according to SNIP-50-101-2004 is performed using crushed stone or lean concrete.

Next, we take a closer look at the device of concrete preparation for the foundation.

What is the preparation for the foundation?

First of all, we need to figure out why we need preparation at all?

When it comes to pouring concrete, rather than erecting a structure from prefabricated blocks, then it allows you to solve several tasks simultaneously:

• It protects the concrete mass from fluid leakage, thereby improving the quality of the base.
• Counteracts the pressure of the soil and weakens its negative impact on the structure.
• Provides convenience when installing the reinforcement cage with your own hands, as the procedure is performed on a flat surface.

Types of training

As mentioned above, several options for arranging the site under the base are allowed using:

• Rubble;
• Thin concrete;
• Profile membrane.

Now let's take a closer look at the features of each option.

Rubble pillow

This type of construction site is used to save money, as the price of rubble is low in itself, besides it reduces the consumption of cement. The thickness of the pillow layer must be at least 20 cm.

This pillow is laid in the following order:

• First of all, crushed stone or gravel is poured at the bottom of a trench or trench (if concrete preparation is performed under the foundation slab).
• Then the layer is carefully compacted.
• After that, the rubble is filled with bitumen.

The disadvantages of this technology include insufficient substrate stiffness. In addition, to build a foundation on the rubble is not very convenient. Therefore, such a pillow is used, as a rule, in the construction of technical and auxiliary outbuildings.

Concrete

This variant of the arrangement of the substrate provides the most correct process for the construction of the foundation. In addition, it eliminates the possibility of subsidence of the soil.

It should be noted that lean concrete is far from the cheapest option, but it is used quite often. The peculiarity of the skinny solution is that it contains no more than 6 percent of cement, the rest is sand, gravel and rubble.

The thickness of the substrate is 50-100 mm. This indicator depends on the weight of the future structure, the type of soil and the level of groundwater.

Tip! When building a cushion of rubble, it is better to use the material of small and medium fractions.

Most often, a concrete pad is used in the construction of tape and slab reinforced structures. This is due to the peculiarities of the technological process, providing for the rigid installation of grids and frames in the body of the future foundation.

In addition, building on concrete is much easier, especially in the winter season.

Profile membranes

This technology is a modern version of the preparation for the foundation, which is an alternative to the use of crushed stone or concrete. Its feature is the lack of wet work. In addition, this method allows you to speed up the construction process and save money.

Concrete preparation procedure

Now let's take a closer look at how concrete preparation is performed using lean concrete.

So, the instruction looks like this:

• The first step is to mark the construction site in accordance with the design data.
• After that, trenches are excavated to the calculated depth. If a monolithic slab is used as a foundation, dig a pit.
• Then the area set aside for the foundation should be leveled and covered with a layer of crushed stone about 10 cm thick.
• A layer of rubble should be tamped. For this you can use a vibrating plate.
• The next step is the installation of formwork height. Its height depends on the thickness of the concrete layer, but must be at least 15 cm, as this will allow you to successfully place the reinforcement, and not more than 30 cm.
• Next, the pillow must be strengthened with the help of reinforcement, using rods with a cross section of at least 8 mm. You can also apply for this purpose the grid.
• After that, you need to perform a concrete solution. Cement grade M50 and higher is used as a binder.

• Then formwork need to pour concrete under the top edge. Concrete at the same time should be tamped.
• Next, you need to insert into the solution bars of reinforcement, which will be able to fasten the foundation with a pillow. They should rise above the concrete by about 20-30 centimeters.

This completes the cushion preparation process. It remains to wait until the concrete finally hardens and then you can proceed to the construction of the foundation.

Tip! After the base is built, it may need to be machined — leveling, making holes in it, etc. — like operations are performed with a diamond tool, for example, diamond drilling of holes in concrete or cutting reinforced concrete with diamond circles is often performed.

Conclusion

Concrete preparation under the base is an important stage in the construction of the foundation. It depends on the quality of the latter, and hence the durability of the entire structure. Therefore, it is necessary to carry out the preparation responsibly, in accordance with the above technology. (See also the article Aligning the concrete floor: features.)

From the video in this article, you can get more information on this topic.