Repair mix for concrete: restore the integrity of the

Repair concrete mixes are used when we need to repair surface damage without dismantling and re-pouring. Of course, the strength of the structure may be slightly reduced, but the final state will still be much better than before the repair.

Below, we will tell you which mixtures can be used to seal cracks and cracks, how to prepare such products yourself, and what to look for when using them.

General issues of repair of concrete structures

Most common damage

Concrete is a fairly durable material, and for this reason it is widely used in construction. However, such surfaces are subject to wear, because sooner or later they need restoration.

As a rule, in everyday life, we are faced with either damage to concrete supporting structures (foundations, plinths, walls), or floor screed defects.

The most common problems include:

• Dusting - fine destruction of the surface layer. It occurs as a result of a violation of the technology of casting, as well as with a significant intensity of operational loads. Eliminated by applying film-forming compositions - silyngov.
• Cracks - formed when exposed to strong loads on a small area, as well as during thermal deformations. In addition, concrete may crack during shrinkage.

Tip! To avoid the appearance of deformation and shrinkage cracks, it is necessary to take measures even at the stage of preparing the structure for concrete pouring. For this purpose, various damping tapes, expansion joints, etc. are used.

• Traces of mechanical damage - chips, gouges, holes etc. This also includes traces of structural elements - mortgages, lighthouses, details of the formwork.
• Level drops due to uneven shrinkage of the base.

And if in the latter case it is necessary to carry out a large-scale restoration of almost the entire floor, then when cracks or hollows appear, the concrete repair mixture will help to restore the surface.

Types of mixtures

For performance of repair work the most different structures are used. Their range is very extensive, but still it can be divided into two groups. The features of materials are easiest to analyze by studying the table below:

As for the material, non-shrink cement is widely used for the manufacture of such compounds, as well as polymers - epoxy resin and polyurethane. For all the tools in this category is characterized by fairly rapid curing, because they are used for express recovery - when there is no time to wait for the full strength of the concrete structure.

An additional advantage may be the presence in the composition of the repair mixture of fiber - steel or polymer fibers. When curing means fiber for concrete strengthens the edges of the damaged base, significantly increasing its strength. True, the price of such reinforcing agents will be somewhat higher.

Independent production

If you do not want to spend money on the purchase of branded material, you can easily make a mixture to repair concrete surfaces with your own hands. Of course, its effectiveness will be somewhat lower, but it is quite suitable for domestic needs.

For the preparation we need:

• Glue PVA or bustilat, diluted with water in a ratio of 1: 3.
• Cement - 1 part.
• Sand, sifted through a fine sieve - 3 parts.

Preparing the material immediately before the start of repair.

For this:

• We pour the cement-sand mixture into a tank with a wide mouth.
• Add glue suspension to dry material, gradually mixing the solution manually. It is important not to overdo it with water - the composition should be quite dense.
• When all the material will be in the tank, take a drill with a nozzle-mixer and knead the composition until complete homogeneity. As a rule, it takes about three to five minutes.

Method of repairing damage

Foundation preparation

Usually, any mixture for the repair of concrete surfaces is accompanied by instructions that clearly regulate the process of its use.

Here we provide only general recommendations, which should be followed in any case:

• To begin with, we need to inspect the damaged area and approximately estimate the amount of material that we need.
• Then we remove the concrete fragments, dust, trash, etc. from the crack. For small defects, you can use a stiff brush, and significant damage is more convenient to clean with a sandblaster or waterjet apparatus under high pressure.
• To fix the edges, the crack can be deepened 20-50 mm below the line of natural destruction. In the process of jointing cracks, cutting of reinforced concrete with diamond circles is often used, which makes it possible to obtain ideally smooth edges and eliminate all weakly adhering areas.

Tip! On longitudinal cracks, experts recommend cutting through the transverse grooves in increments of about 20 cm for more effective anchoring.

• Special attention should be paid to the reinforcement cage. All metal parts protruding beyond the concrete pavement, we clean to shine. Then we apply an anticorrosive primer on the cleaned rods to prevent the material from oxidizing during the process of hydration of the repair mixture.
• If the depth of the defect exceeds 50 mm, then additional reinforcement should be laid in it. The reinforcement is mounted in such a way that the metal is subsequently covered with a layer of mortar not thinner than 20 mm.

After all this work has been done, the site is again dedusted. Then we moisten all surfaces, trying, however, to prevent the accumulation of large drops.

Preparation and application of the composition

A self-prepared mix for repairing concrete surfaces can be applied immediately. But the compositions of industrial production need to properly dilute with water.

Only in this case the material will acquire the characteristics necessary for the effective filling of the seam and polymerization:

• As a rule, both flowing and thixotropic mixtures require a relatively small volume of liquid. On average, 120 to 250 ml of water is consumed per 1 kg of dry material.
• Cool water in the minimum volume (exact figures are specified in the instruction) we fill in capacity or a concrete mixer. Then we fall asleep dry component, gradually mixing the material.

Note! Manual processing does not provide the desired uniformity of the means, therefore it is necessary to use an electric mixer. For small volumes, use of a drill with a special nozzle is allowed.

Further, our actions depend on what material is used for repair.

Casting tools applied in this way:

• Along the perimeter of the restored area we assemble the formwork. It is desirable that its height was at least 50 mm greater than the planned level of coverage.
• Pour the prepared fluid mixture onto the concrete, spreading it evenly from one side to the other. This sequence of actions will avoid the capture of air bubbles.
• Vibration compaction of the composition in most cases is not required. To remove air pockets at the junction of the surface and formwork, it is sufficient to hold a metal strip around the perimeter.

We work differently with thixotropic agents:

• We collect a small amount of material on a spatula or grater.

• With effort we press the compound into the crack, filling it in one pass for 15-25 mm.
• After waiting for some time to polymerize the layer, repeat the treatment until the defect is eliminated.
• Smooth down the surface with a moistened steel trowel, trying to disguise all the projections and irregularities. Re-alignment using the same tool is carried out after the mixture grasps, i.e. at least half an hour after application.

So that the repair compound does not crack, it must be kept wet for a day, and in the heat - up to three days or more. To do this, periodically spray the reconstructed area with water from a spray bottle or hose, after which we cover it with polyethylene or sacking.

Tip! It is desirable that during the entire period of drying in the room there were no drafts and sudden changes in temperature.

Conclusion

With optimal use of the mixture for the repair of concrete will help restore the surface of almost any structure. Compliance with the rules of the preparation of the solution and its application makes it possible to preserve the mechanical properties of the surface, and in some cases seriously improve them. The video in this article will help to understand the nuances of technology to those who are planning to do this repair themselves.