Cracks in concrete: the main causes and methods of

Cracking is one of the most common and dangerous defects in a concrete surface. Cracks in the concrete after casting, during operation or after machining may occur due to the influence of a huge number of factors.

The cause of this defect can be hidden both in improper preparation of the solution, and in its transportation, installation or illiterate care.

Causes of surface cracking

Causes of cracks in concrete can be very different.

There is a division of these factors into the following groups:

1. Even at the stage of preparing the solution, an error may be made in the technology of preparing a building material, for example, the ratio of such components of the solution as water and cement may be disturbed. As a result of such violations, the building material will belong to another brand, and accordingly will not meet the stated requirements;
2. Too long process of transporting concrete mass can lead to the beginning of such a process as "welding" of concrete;
3. An error in the calculations at the design stage may lead to the fact that an excessively high load will be exerted on the finished monolith already at the stage of operation of the finished product. The cause of the cracks in this case may be insufficient reinforcement;
4. Difficult operating conditions. So, for example, the designers may not take into account the presence on the site for construction of heaving soils;
5. Violation of the technology of working with the mixture at the construction site:
6. It is often possible to encounter such a situation when water is added to the solution in order to make it easier to fill and level. But excess moisture interferes with the normal process of curing;
7. Also, cracks in reinforced concrete structures may result from improper placement of steel reinforcement or insufficient compaction of the concrete mass at the casting stage, as well as improper installation of the formwork panels;
8. Construction of additional extensions to the object without additional load on its surface.

Crack classification on concrete

Instructions for eliminating defects that arise are primarily based on the type of crack.

There are the following types of similar defects:

1. Through. It arises due to the action of axial tensile forces or forces with a low level of eccentricity;
2. Cracks in the stretched zone. Are the result of bending of the product or are arranged perpendicular to the rods of the reinforcement;
3. Defects caused by shear force, or shear cracks. Such cracks are directed at an angle to the bars of the reinforcement;
4. Cracks located parallel to the reinforcement bars may occur in the area of ​​anchoring if improperly produced, as a result of ground heaving or uneven draft of a monolithic structure;
5. Small cracks may occur due to temperature variations on the surface of the concrete product and its inner layers;
6. Hair cracks can also occur due to temperature fluctuations, but their depth does not exceed a couple of millimeters.

Defect repair methods

In a freshly applied solution, it is possible to eliminate defects of this kind without much cost, simply by condensing the mixture again.

Note! Freshly considered a solution, after pouring which took no more than 1-2 hours.

Well, in order to remove cracks in an already frozen structure, you will have to use one of the following methods:

• Injection method. A repair compound is injected into the crack under pressure;

Note! Some repair compounds may, in addition to embedding cracks, also displace water from the cavity, but their price will be noticeably higher.

• Termination Method, providing for filling the defect with concrete.

Sealing crack

This method is most often used in practice, because every owner can do it with his own hands without the help of professionals.

Council As a rule, for its implementation it is necessary not only to fill the void with a solution, but also to pretreat the surfaces in order to ensure the best adhesion.

In order to self-repair cracks on the surface, you must prepare or purchase the following materials and tools:

• Sander;
• Zubilo;
• Putty knife;
• Hammer;
• Brush with hard metal bars;
• A vacuum cleaner;
• Trowel;
• Brush;
• Rake or rule;
• Pure water;
• Cement flour;
• Wire;
• Glue;
• Gladilka made of metal.

Now it remains to answer questions about how to cover up the cracks and how to do it right?

This task involves the execution of the following stages of repair work:

1. Preparatory events. First you need to inspect the crack itself and identify weak spots around it. Further, with the help of a chisel and a hammer, it should be expanded and deepened to a minimum of 5 mm. This is necessary so that the repair compound is firmly hardened in its depth and does not fall out;

Council If the need arises, you can deepen the crack with a sharp spatula edge.

1. Now the crack should be thoroughly rinsed, removing the remaining dirt and particles of cement stone. To completely dedust the surface, use a vacuum cleaner. Using a sponge will allow to dry the crack and rid it of excessive moisture;
2. If in the process of fracture expansion, the reinforcement was bare, then, before starting work with the mortar, treat the metal using primers with anti-corrosion effect;
3. In order to seal, professionals recommend the use of a sand solution consisting of cement and sand in a ratio of 1 to 3. You can also add PVA glue to this solution;

Council Sufficiently deep surface defects should be filled in several layers by necessarily wetting each layer to ensure high-quality filling and uniform drying of the solution.

1. In some cases, cracks should be reinforced using small pieces of reinforcing metal wire;

1. The surface of the crack filled with mortar is carefully leveled with a trowel;
2. The remaining protruding parts of the solution should be sanded using a specialized grinding machine.

How to prevent monolith cracking

The most common and most common cause of cracks in concrete is non-compliance with the proportions of water and cement in the solution. It is such a violation of technology leads to a decrease in the quality of the concrete itself and subsequent cracking in intensive mode. For this reason, special attention in the production of works with concrete should be given precisely to these proportions.

In addition to this error, in the process of mixing concrete mix, the compaction of mortar with the help of specialized vibrators is of considerable importance. One should not underestimate also the importance of proper and competent care for the concrete screed during its drying and curing.

Council In order to prevent too much evaporation of moisture from the surface and to prevent uneven drying of the mass, the solution should be covered with a damp cloth.

Especially dangerous are cracks that occur on the surface, the operation of which is carried out in conditions of temperature differences with frequent transitions through the 0 degrees mark.

The fact is that when freezing moisture, which falls into the very depth of the crack, it expands, deepening and expanding the size of the defect. The result of such processes may be the exposure of metallic reinforcement and the occurrence of corrosion, which will reduce the strength of the whole structure.

In order to timely detect cracking and eliminate this defect before irreparable consequences occur, you should regularly inspect the concrete surfaces, fix the detected defects and seal them. Thus, you will have the opportunity to localize cracking at a very early stage and at the same time reduce the amount of repair work.

Council In no case do not allow yourself to be lazy and postpone the seal for later, even if we are talking about very small defects.

Finally

Cracks on the concrete surface, be it shrinkage cracks in concrete according to SNiP or cracks in foam concrete, this is the first sign that something was done wrong during the construction process. And if you don’t reverse what has been done, then you should take care of the integrity of the concrete monolith already at the operation stage, repairing the defect immediately after its occurrence and not allowing the proliferation of cracks and increasing their number.

And the video in this article will tell even more about how cracks are and how to deal with them.