Concrete construction. causes of destruction, repair

In most cases, damaged or worn concrete products are cheaper to repair than to replace them. But in order to repair concrete structures led to obtaining a quality result, the technology of its implementation must be respected. Our article will introduce you to it.

Causes of concrete destruction

The deterioration of the properties and the violation of the integrity of this material can occur for a number of reasons. They are presented in tabular form.

Tip! To carry out a high-quality repair, a thorough preliminary analysis of the damaged elements is necessary. It can provide an examination of concrete structures. In particular, it can be used to establish the depth of carbonization, the degree of expansion of concrete and its cause.

General procedure for the repair of concrete products

Surface preparation

There are 4 ways with which you can prepare the concrete surface for repair procedures:

• mechanical - It involves the use of various tools, such as a hammer drill, a jackhammer, a grinding machine. other equipment can also be used, such as sand and shot blasting units;
• thermal - the use of burners using propane or oxygen with acetylene. In this case, the material should be heated to a temperature not higher than 90 degrees;
• chemical - surface treatment with phosphoric or hydrochloric acid;
• hydraulic - the use of water-jet installations, creating a pressure of 120 atmospheres and above.

In addition to these methods, mixed processing options are also possible. They are a combination of the above two methods. The following table will tell you more about these processes.

Consider in detail the mechanical surface treatment. It is carried out as follows:

1. With the help of diamond tools around the perimeter of the site to be repaired, incisions are made with a depth of 10 millimeters or more. In this case, the resulting contour should not contain sharp corners, otherwise it will be difficult to further work;

1. A perforator or a jackhammer removes damaged concrete from the marked area;

1. the surface to be repaired is roughened — this is done using a perforator with a nozzle in the form of a toothed blade or a water-sandblasting installation. Obtaining protrusions and depressions with a depth of 5 millimeters will be quite enough.

Tip! During the work, the valves should not be damaged by diamond discs or exposure to a jackhammer or a hammer drill. All this will inevitably lead to a decrease in structural strength. To avoid this, you should use a locator that will help determine the location of the reinforcement in the thickness of the structure.

Rebar cleaning

The next stage of work is the cleaning of reinforcing bars. It is done by hand with a brush or by using a sandblaster.

Steel rods may be exposed in whole or in part. It depends on their condition and specific situation. If it is a question of complete exposure, then a gap of at least 2 centimeters should remain between the metal and the concrete. For valves with a diameter of 5 mm or less, this distance can be reduced to 1 centimeter.

The SNiP on “Concrete and reinforced concrete structures” under number 52-01-2003 prescribes that, if necessary, reinforcement of a construction object, additional steel elements can be installed in it. When installing new rods between them and the old reinforcement, a certain distance must be maintained. It is at least 2 centimeters, for elements with a diameter of 6 millimeters and at least 1 centimeter for reinforcement of smaller thickness.

Cleaning concrete from dust and moistening the surface

Before applying the repair solution, the treated surface must be free from dust and impregnated with water. Cleaning is done first with brushes, and then with a compressor that delivers a powerful stream of air.

Moistening is carried out by brush or water jet installation. This equipment is used no earlier than half an hour before the concreting of structures begins. Moistening is carried out until the surface of the material is completely saturated with water. Excess moisture is removed by supplying compressed air from the compressor or a conventional foam sponge.

Formwork installation

If in the course of repair it is planned to use bulk mixtures, then for their laying it will be necessary to create formwork. It is made of waterproof durable material and is fixed so that it can withstand the pressure of the cast solution.

Formwork must be sealed.

This is achieved in the following ways:

1. the use of polystyrene foam or other special materials;
2. embedding the formwork slots with repair mortar.

Tip! Do not use fabric to seal the formwork. Otherwise, after pouring and curing the composition, serious difficulties will arise with its separation.

Before pouring the mixture, the formwork structure is necessarily soaked with water. This is necessary so that after pouring the solution, it does not absorb water from it and thus does not cause its dehydration.

Concrete Mixing

For the restoration of concrete structures used special repair mixtures sold in dry form. Their price may be different - depending on the manufacturer, the volume of the mixture and other factors. These formulations should be prepared in full compliance with the instructions contained in the instructions attached to them.

For mixing such solutions used construction mixer or concrete mixer. The mixer is a drill with a nozzle in the form of a spiral. It is used to create small volumes of the mixture.

For the preparation of a significant mass of mortar used concrete mixer.

This is done as follows:

1. The required amount of water is poured into the tank;
2. The contents of the bag with the repair mixture are poured into the mixer with one quick motion;
3. Three or four minutes produced mixing the solution until a plastic mixture. If the composition is too thick, you can add a little water and mix it for a couple more minutes.

  Tip! For high-quality styling should create the amount of the mixture, which can be put for a period of time not exceeding 45 minutes. Add water to the mixture, which has already begun to seize can not, because it will lead to a deterioration in the quality of the material obtained.

Laying concrete mix

The next stage of work, which will tell you about our instructions for repairing concrete structures - is laying concrete solution.

It can be produced at temperatures from +5 to +35 degrees Celsius. During this process, the prepared mixture is poured into the formwork in a continuous stream.

The composition is made in one of two ways:

• manual - using buckets and carts;
• mechanical - using a mixing and pumping unit.

Filling is carried out only on one side - this helps prevent the formation of air pockets. For the same purpose, during the whole process, it is necessary to carefully ensure that the mixture completely fills the space of the formwork.

The laid structure is leveled by rake or rule. If necessary, it is smoothed.

To apply the mortar with a thickness of less than 3 centimeters, use a trowel. Of course, the mixture should have a plastic character.

For final finishing, a sponge grater is used, with which the resulting surface is carefully smoothed. Such processing should be started when, when the fingers touch the mixture, they do not sink, but only leave a small mark. The dismantling of concrete structures is made a day after pouring the repair solution.

Care for fresh mix

Flooded composition needs care. It should start immediately after the concreting process. The purpose of this work is to protect the created surface from moisture loss due to its evaporation. The duration of care may be different depending on the temperature and humidity conditions:

• 24 hours - in case the air temperature does not exceed +20 degrees and there is high humidity;
• 48 hours - if the atmospheric temperature exceeds +20 degrees, low humidity is present and there is wind.

Especially important is the observance of care measures within the first 24 hours from the moment of pouring the solution. If at this time they are not implemented, microcracks may appear on the concrete.

To prevent this phenomenon, use one of the following methods:

• periodic wetting of the surface with water;
• laying wet burlap;
• pouring water;
• processing of the structure with a special film-forming composition. For example, it could be MASTERCURE 114.

Conclusion

Concrete products are destroyed under the influence of various negative external factors. To establish the specific cause of the destruction of the material and the degree of its impact will help a special examination. Its results will be useful for subsequent repairs.

Their sequence was described above. For more information, refer to the video in this article.