Concrete is considered very durable, reliable and durable material. However, under the influence of various influences, it begins to collapse. Sometimes defects arise after a short time, and they can be eliminated with special repair compounds.
Concrete is a fairly strong, durable and durable material, but it does not last forever. Cracks and breaks may appear on it. And in such cases it is necessary to use special mixtures for its repair.
Repair compositions for concrete are special products that contain cements, fillers, sand and various additives that impart certain properties to the solution.
Scheme for repairing concrete defects with exposed reinforcement: a – concrete defect with exposed reinforcement; b – removal of destroyed concrete, application of a protective layer to the reinforcement; c – restored section of structure 1 – building construction; 2 – fittings; 3 – material “KTtron-primer”; 4 – thixotropic repair material “KTtron” (depending on the project).
Dry repair compounds are completely ready for use after mixing with water. They are used to eliminate deficiencies in concrete floors, walls, bridges, stairs, roads and other concrete structures.
Dry repair compounds are intended for:
- repairs load-bearing structures(beams, columns, floor slabs, etc.);
- repair of road surfaces (runways, parking lots, etc.), industrial floors, floors on warehouses and so on.;
- protection of concrete and iron concrete surfaces from corrosion.
Currently, repair compositions for concrete are presented in a wide range: from different manufacturers, with different properties and different price categories. Defect removal agents are divided into two main groups: thixotropic (for vertical surfaces) and casting (for horizontal planes). To increase the reinforcing properties, fiber fiber can be added to the mixture.
Selecting a mixture for concrete repair
Panel repair diagram from cellular concrete with a destruction depth from 20 to 50 mm and an area of up to 0.5 m2: 1 – panel; 2 – nails; 3 – metal wire; 4 – destruction contour.
The choice of mixtures for depends on several parameters: the type of damage, surface defect, as well as operating conditions.
Strengthening the concrete surface. Often concrete surfaces bearing heavy loads have a weak surface (floor slabs, screed, etc. monolithic structures). In such cases, primers should be used deep penetration for concrete.
Leveling the surface. Uneven surfaces are one of the most common defects concrete structures. IN in this case Deep penetrating primers are also great. For vertical surfaces, thixotropic dry mixtures should be used; they adhere well to the surface, do not blur and adhere well to vertical planes. In addition, they have high strength, are frost and water resistant and have minimal shrinkage.
When repairing particularly critical areas, it is necessary to use reinforced fiberglass. There are also special compounds for quick repairs that harden in a minimum amount of time. In this case, the thickness of each layer should not exceed 35 mm.
Exposed reinforcement in concrete structures must be treated with an anti-corrosion primer.
Dry casting mixtures are used to level horizontal surfaces. Such compositions have a more liquid consistency, unlike thixotropic ones, and are poured onto the surface. The thickness of one layer can reach 10 cm. The mixture has minimal shrinkage, high coating strength and quick setting.
Repair of cracks. Another common defect of a concrete surface is cracks. To repair cracks, as a rule, the same compounds are used as for leveling the surface.
When choosing a composition for concrete repair, it is worth taking into account the operating conditions. During production, various components can be added to the mixture to impart certain properties, such as frost resistance, water resistance, rapid hardening of the composition, etc.
Floor leveling technology
You can level horizontal surfaces yourself. Although the work is quite labor-intensive and requires knowledge of technology, if you follow all the rules, you can get a perfectly flat plane with your own hands.
To level the floor, a cement-sand screed is required. Before starting work, the surface must be cleaned of dirt, dust and old coating. Then the plane is treated with a primer, which promotes a more uniform spreading of the solution.
Next, you should determine the highest point, according to which the floor will be leveled. After this, beacons are installed, which can be used as metal corners, profiles or pipes. Beacons are installed so that their height is at the same level. For this it is better to use a laser level.
Schemes for sealing expansion joints of concrete dams: a – diaphragms made of metal, rubber and plastics; b – dowels and gaskets made of asphalt materials; c – injection seals; d – beams and slabs made of concrete and reinforced concrete; 1 - metal sheets; 2 – profiled rubber; 3 – asphalt mastic; 4 – reinforced concrete slab; 5 – wells for cementation; 6 – cementation valves; 7 – reinforced concrete beam; 8 – asphalt waterproofing layer.
After installing the beacons, pouring the screed begins. The layer thickness should not exceed 40 mm. A solution pre-mixed in plastic or metal container, poured onto the base, then leveled with a spatula.
After pouring, the screed must dry, this may take up to two weeks. On the second day after pouring, it is necessary to remove the beacons and seal the seams with a grouting solution.
When drying, the screed must be covered plastic film. It is recommended to periodically moisten the surface with water. This will prevent cracking of the surface and give the screed greater strength.
You can also repair horizontal concrete surfaces using a self-leveling mixture. Such compositions are used in cases where the surface has small defects, uneven areas up to 3 mm. The result is a perfectly flat surface.
Pothole Removal
Repair scheme for chipped edge concrete covering at the seam: a – before repair; b – after repair; 1 - existing concrete; 2 – chipped edge and crack in concrete; 3 – crushed stone; 4 – dirt; 5 - expansion joint; 6 – waterproofing; 7 – freshly laid concrete; 8 – polyethylene film; 9 – mortgage board.
Often defects such as potholes appear on the concrete surface. They are eliminated as follows. First, an incision is made along the perimeter of the damage, the depth of which should not exceed 2 cm. To do this, it is better to use a tool such as a grinder with a diamond blade. After the cut is made, the remaining concrete is removed using a hammer drill and chisel.
Next, remove dust and dirt. For better removal Remove all debris using a vacuum cleaner or sandblasting equipment. An epoxy primer is applied to the cleaned surface. It provides better adhesion of the composition to. The pothole is then filled with a special compound to repair the concrete surface.
Excess mortar is removed and the surface is leveled using a rule or lath. After this, the patch is cured required time until it dries completely. During this time, the composition acquires its maximum strength. The final stage– grinding the repaired damage.
For repairs, special dry mixtures should be used, and not a regular concrete solution, since repair compositions have special properties that ensure the strength of the coating.
Repairing cracks in concrete
They can appear due to various reasons. At the same time, they can develop further, which negatively affects the strength of the entire structure, or they may not spread further. In any case, the defect must be repaired.
Depending on the width of the crack and the material used to seal the crack, there are various ways troubleshooting:
- injection. Vertical cracks are always eliminated this way. For injection, special equipment is used - an injection packer, with the help of which the crack is filled with a repair compound under pressure;
- saturation. The saturation (impregnation) method is used to eliminate surface cracks. As a rule, such defects occur on horizontal or inclined surfaces. When infiltrating cracks, the repair compound is pumped into the crack without pressure.
Cracks can also be eliminated in the following way. First, the crack is sawed to a depth of approximately 20-50 mm (depending on the size of the crack) and a width of 10-20 mm. After this, excess concrete is removed, dust and dirt are blown away. Then the cleaned cut is filled with a repair compound. It is worth considering that if the concrete does not generate much dust during operation, then the composition can be used cheaper and simpler. If the concrete crumbles, then you should choose a higher quality and more expensive product.
Concrete is the most popular construction material, characterized by high durability and strength, wide application, absolute non-flammability and low cost. However, violations of the technology of its preparation and installation lead to rapid wear of products and structures. Accelerated destruction of concrete is also facilitated by operation in aggressive environments and increased mechanical loads. As a result, the material loses its design strength and becomes covered with cracks and cavities.
For restoration, a traditional solution is not used, but a specially created repair mixture for concrete with suitable technical characteristics. Such compositions are produced and packaged in the form of a dry powder, which is diluted with water in a certain proportion. To give them special properties (frost resistance, moisture resistance, speed of hardening), various ingredients are added (plasticizers, modifying additives, fractional fillers).
Ready-made formulations for concrete repair are conventionally divided into groups.
By area of application:
- For the restoration of structures and products experiencing increased mechanical loads (beams, columns, floor slabs, load-bearing walls).
- For strengthening reinforced concrete elements susceptible to corrosion.
- For repair road surfaces and floors.
According to the complexity of the composition:
- Single-component (cement with large and small fractions).
- Two-component (epoxy with different degrees of fluidity).
- Multicomponent (liquid polyurethane).
There are also repair compounds for concrete with special conditions Applications:
- Thixotropic - for vertical surfaces.
- Casting - for horizontal planes.
- Fast-hardening - for urgent repairs and eliminating leaks.
- Frost-resistant - for use when low temperatures Oh.
- Industrial and domestic use.
Self-leveling mixtures are used when the thickness of the working layer is no more than 100 mm, and quick-hardening mixtures, which gain the necessary strength after 6 hours, are used up to 40 mm.
Selection method
Correctly selected repair dry mixture for concrete and strict adherence to the technology of its use will ensure the strength and durability of the product or structure. When purchasing a composition, you should take into account the nature of the damage, the size of the affected area and the operating conditions of the concrete. After hardening, the repair mortar should not shrink or delaminate. Its compatibility with the surface being restored and the required level of adhesion to it are extremely important. Almost every manufacturer of repair compounds additionally offers branded deep penetration primers that bind concrete and ensure high adhesion to the solution.
When choosing the type of mixture, the extent of surface damage must be taken into account. Significant potholes, cracks and differences in floor levels are eliminated with solutions with large fractions. To seal small sinks and cracks, it is enough to buy a fine-grained concrete repair mixture with increased plasticity. If the product or structure is used in extreme conditions, then the restorative composition must contain additional ingredients that give it special qualities, for example, frost and water resistance.
Technology of use
Floor repair
To eliminate major damage on horizontal surfaces and differences in concrete floors, inexpensive dry cement-sand mixtures. Before application ready solution The work area should be cleaned of debris and dust, degreased, and then treated with a deep penetration primer recommended by the manufacturer. After assessing the extent of damage, it is determined required amount repair mixture for concrete. The recommended thickness of the cement-sand screed does not exceed 40 mm. Control beacons are set and the solution is drawn out, which will gain strength within 2 weeks. All this time, the surface of the screed, covered with plastic film, should be periodically moistened with water to prevent it from cracking. To eliminate small floor defects, it is advisable to use self-leveling, finely dispersed self-leveling compounds with increased plasticity.
Crack repair
Before using the solution, the cracks in the concrete surface are usually widened. To do this, grooves up to 50 mm deep are cut around them with a diamond wheel or grinder, and then the destroyed material is selected with a hammer drill or chisel. Work area cleanse compressed air from debris and dust, treated with impregnation, after which a repair solution is applied. Cracks on horizontal and inclined surfaces are eliminated using the saturation method without overpressure. To fill vertical cracks, inexpensive and practical repair mixtures MBR 300 and MBR 500 for concrete are often used, which differ in strength characteristics and hardening speed. In some cases, to fill internal voids and deep cracks, they resort to the injection method using a special device - a packer. The repair compound that has come out on the surface under pressure is removed with a lath, and after hardening it is ground.
The choice must be approached as responsibly as possible. After all, if work to restore a concrete foundation is carried out using unsuitable or low-quality materials, the structure only loses strength, not to mention the fact that its cost increases significantly.
What causes concrete to fail?
Concrete structures are destroyed under the influence of the following negative factors:
Chemical reactions caused by increased carbon content in concrete. These processes provoke a violation of the proportions of water and cement content in the solution.
Chemical reactions caused by the action of chlorine ions contained in road salt, which is used in the cold season to protect reinforced concrete road surfaces from ice. As a result of these processes, oxidation of reinforcement in concrete begins.
Action of moisture. Water seeps into concrete cavities. When frozen, it crystallizes and causes destruction and cracking in the concrete structure.
Mechanical factors - shocks and dynamic impacts exceeding permissible loads provided project documentation etc.
Seismic processes.
Natural disasters - floods, hurricanes, etc.
Fires.
Failure to comply with technological standards and violations at the construction stage. For example, long downtimes at the concreting stage can lead to poor adhesion of new concrete to the old base. This entails the formation of working (cold) seams and over time reduces the strength and damages the aesthetics of the structure.
The main stages of concrete repair activities
Work is carried out in the following sequence:
Examination. At this stage, specialists assess the severity of the damage caused and analyze possible reasons who provoked them. To do this, the size of cracks, the thickness of the protective layer, the intensity of carbonization processes, etc. are measured. Based on the results of the surveys and their recommendations, a plan is drawn up repair work and the means intended for this are selected.
Preparatory work. The damaged layer and signs of previously carried out restoration measures are completely removed from the base to a dense, clean and solid base. Its surface is cleaned of all types of dirt, traces of paint, oils, etc.
Processing of reinforcement. Bare reinforcement bars are carefully cleaned from traces of corrosion and covered with protective compounds.
Repair work. Construction mixtures for concrete repair are applied manually, by pouring (for example, into formwork) or by spraying/gunning.
- Recovery by using special means. Protective compounds on an organic or inorganic basis protect concrete from negative impact environment, pollution and other aggressive external factors.
If necessary, apply over the protective layer decorative layer.
Types of mixtures for concrete repair
Depending on the purpose and nature of use, there are the following types compositions:
Compositions used for the restoration of load-bearing concrete structures (floors, beams, highways, floors in industrial premises and other types of coatings experiencing strong dynamic loads).
Compounds used for non-structural restoration of concrete, leveling the surface of the base and sealing minor defects.
When choosing a repair composition for concrete, the nature and extent of damage, the specific operating conditions, technical specifications concrete and other factors.
Concrete repair mixtures from MAPEI
MAPEI offers various materials for a complete and quality repairs reinforced concrete structures:
- Means for anti-corrosion protection of fittings.
- Materials for repair of reinforced and unreinforced concrete.
- Leveling mixtures.
- Waterproofing compounds.
- Epoxy resins for repairing cracks using the injection method.
- Finishing decorative and protective materials, etc.
The most popular materials for complex repair concrete from MAPEI are produced in Russia, at the company’s own factories.
The most popular mixtures for concrete repair from MAPEI
Mapegrout Thixotropic is a dry mixture for the repair of reinforced concrete and concrete structures, reinforced with polymer fiber, with compensated shrinkage. It is characterized by excellent adhesion to concrete and steel, frost resistance, water resistance, and mechanical strength. Applied in a layer of 10 to 35 mm. Thanks to its thixotropic properties, it is suitable for use on both vertical and horizontal bases, without requiring the use of stationary formwork. Gains strength quickly. This dry mixture is intended for surface restoration concrete foundations- for example, for filling formwork marks, smoothing open reinforcing rods, repairing upper layers industrial floors, ramps, etc.
Mapegrout Hi-Flow is a dry mixture for repairing concrete by pouring into formwork. Indispensable where, due to the depth and specificity of the damage, materials with high fluidity rates are required - for example, for restoring road surfaces, filling the distances between elements of concrete structures, etc. Apply in a layer of 10 to 40 mm. Upon contact with water, it forms a concrete mixture that is not subject to delamination, resistant to abrasion, low temperatures and has waterproofing properties.
Mapegrout 430 is a concrete repair material characterized by controlled shrinkage and medium strength values. Used for repairing concrete foundations destroyed as a result of corrosion processes in reinforcement. It is applied in a layer of 5 to 35 mm without the use of formwork on vertical surfaces. In order to ensure the composition can fully expand on open construction sites, it is recommended to use it in combination with the Mapecure SRA additive.
Mapegrout SV-R Fiber is a dry repair mixture that quickly gains strength and is intended for the repair of serious defects where the coating is subject to heavy loads and long-term downtime is not possible (road surfaces, airport runways, industrial premises etc.). Can be used under negative temperature conditions from -5*C. Apply a layer of 20-50 mm.
ARB-10 and ARB-10F are concrete repair compounds that quickly gain strength. Characterized by high stability to mechanical damage, water resistance and compensated shrinkage. Thanks to the presence of steel fibers in the composition, ARB 10F can be used to repair foundations subject to severe loads. These products were developed specifically for the restoration of airport runways, bridges, industrial floors, etc. Apply in layers from 50 to 300 mm
Mapefill and Mapefill 10 are expansive, flowable concrete mixtures that do not shrink and quickly gain strength. Used for base fixation and anchoring of industrial equipment. In addition, it is suitable for filling seams, technological cavities, etc.
Stabilcem is a cement binder for the preparation of injection solutions for repairing cracks in concrete, brick, and stone using the injection method. It is also used to compact foundations and fill hard joints.
Compositions:
Mapelastic is an elastic composition for protection against water load and atmospheric influences, both external (balconies, terraces) and underground parts structures (basement walls, swimming pools, water tanks, etc.), as well as plastered surfaces and old floors.
Idrosilex Pronto - rigid waterproofing for the protection of underground structures: basements, foundations, channels, swimming pools, under positive and negative water pressure
We focused only on the most famous repair compounds from MAPEI. The company's product range is so wide and includes so many materials for different areas construction, that it is simply impossible to list the entire product line in one article.
The process of hardening of all binders in the air is accompanied by an inevitable process of shrinkage.
Deformations that occur during the process of reducing the volume of the cement mixture can cause the formation of cracks in the finished concrete, which will not only negatively affect appearance structure, but will also disrupt its solidity, significantly reducing the operational period.
Dry repair mixtures applied to places where the concrete layer is damaged can correct the situation by restoring the solidity of the concrete structure. This dictates the need to use concrete repair mixtures.
Features of our mixtures for concrete repair
When buying dry mixes for concrete, instead alternative options repairs, the client not only saves own time, but also the budget. The reason for this is the optimal price-quality ratio of our products, which allows us to achieve the first results within 24 hours from the moment of application, which is an order of magnitude faster than traditional analogues.
Among other things, concrete repair is accompanied by an increase in water resistance in the areas where the mixture is applied. This effect is achieved due to the adhesion process that quickly occurs between damaged concrete and a multicomponent non-shrinking mixture.
Concerning temperature regime, the concrete repair composition has high hardening rates, arriving in a temperature range from +5 to +80 degrees Celsius.
The retention period for the consistency of the diluted mixture reaches 60 minutes, which is quite enough for spot application.
Advantages
By choosing our fast-acting materials, the customer enjoys a wide range of benefits. Among them:
- reasonable cost
- Possibility of delivery to the customer's address
- an impressive range of repair mixtures for damage of any type and size
- compliance of materials sold European standards quality, which guarantees durability
Potholes, chips, cracks - all this can happen to any concrete surface. In this article we will tell you how and with what mixtures you can repair concrete.
Types of repair compounds
Concrete is known for its strength, reliability and durability. However, under the influence various factors over time it begins to deteriorate. The reason for this may be poor-quality installation, non-compliance with the proportions of the components, aggressive external environment, mechanical damage. Defects can be eliminated using special repair compounds.
In order to prepare the composition, you need to mix the dry repair mixture with water. It is possible to use special additives that improve some of the characteristics of concrete. Ready-made compounds are used to repair floors, walls, stairs, bridges, roads and other concrete structures.
All repair mixtures can be divided according to their purpose:
- for repairing load-bearing concrete structures, for example, columns, beams, floor slabs;
- for repairing roads and concrete floors;
- to protect concrete structures from corrosion.
The market offers a fairly wide range of repair compounds with different properties, from different domestic and global manufacturers. Accordingly, their quality and price category may differ quite significantly.
Repair compositions must ensure high adhesion to concrete, non-shrinkage and absolute compatibility with it. With their help it is restored load bearing capacity structures, increases water resistance, frost resistance and strength of concrete. In addition, they must be accessible and economically feasible.
According to international and domestic experience, it has been proven that the use of repair mixtures is more effective than the use of traditional cement-sand mortars.
Repair mixtures for concrete are divided into thixotropic and castable. The first ones are used for vertical surfaces, the second ones for horizontal ones. The reinforcing properties can be increased using fiberglass.
How to choose a repair composition
Several factors influence the choice of repair composition:
- type of damage
- defect size
- terms of Use
There are three main types of repair work:
- strengthening the concrete surface
- leveling the concrete surface
- crack repair
To strengthen concrete that carries heavy loads and has a fragile surface (screed, floor slabs), deep penetration primers are usually used.
The most common type of concrete repair is leveling out uneven surfaces. Sealing of vertical surfaces is carried out using thixotropic dry mixtures. They cling perfectly to the surface, stick well to them and do not blur. They have minimal shrinkage and high strength, water and frost resistance characteristics.
Particularly critical areas require the addition of reinforced fiber fiber. Fast repairs are guaranteed special compounds. Their hardening time is up to 6 hours. But they have a limitation on layer thickness - up to 30-40 mm.
Horizontal surfaces are leveled with casting mixtures. They are more liquid and, thanks to this, they are simply poured onto the surface. The mixture sets quickly, has minimal shrinkage and is quite durable. One layer can be laid up to 10 cm thick.
Leveling mixtures are also used to repair cracks in concrete.
The choice of repair composition is influenced by the operating conditions of the structure. If necessary, components can be added to the mixture to enhance various properties, for example, water resistance or rapid hardening.
The most famous manufacturers repair mixtures - BASF, MAPEI, SIKA, from Russian ones - Lakhta, Alit, Consolit, SpetsRemSmes.
Leveling the floor
To level the floor, you need to prepare cement-sand screed. The concrete surface is first cleaned of dust and treated with a primer. After this, they determine the point at which the floor will be leveled, according to laser level beacons are installed.
Next, the screed is poured. Its maximum height should not exceed 35-40 mm. The pre-mixed solution is poured onto the surface and leveled with a spatula. On the second day, the beacons are removed and the seams are sealed with a trowel.
The screed should dry well. This may take up to 2 weeks. The screed is covered with film, and the surface itself is periodically moistened with water. Thanks to this, it will become stronger and will not crack.
Horizontal surfaces can be repaired using a self-leveling compound. They are used in the presence of small defects and uneven areas. The result of use is a perfectly flat surface.
To level the floor I use the following mixtures: “VOLMA-Nivelir Express” (cost: 14 rubles/kg), “Vetonit-2000” (17 rubles/kg), KESTONIT 97 (39 rubles/kg).
Repairing potholes on the floor
At the beginning of work using diamond blade or a grinder, small incisions are made around the damage. Then the remnants of damaged concrete are removed with a chisel and a hammer drill, and the surface is cleaned of dust. For better adhesion of the composition to the concrete, a special epoxy primer is applied to the surface.
After applying the solution, it is necessary to remove its excess and use a lath to level the surface. After complete drying, the composition becomes as durable as possible. The sealed area is sanded.
The following mixtures are suitable for filling potholes: IVSIL EXPRESS-BASIS (cost - 10 rubles / kg), Thomsit RS 88 (30 rubles / kg), "LAKHTA quick repair"(80 rub./kg).
Crack repair
Due to various reasons, cracks appear in concrete. Over time, they can increase, destroying the entire structure. This defect must be repaired.
Vertical cracks are repaired by injection. Using injection method the composition is pumped into the crack using special equipment - a packer.
Surface cracks, which usually form on inclined and horizontal surfaces, are repaired using the saturation method. In this case, the cracks are impregnated with the mixture without pressure.
There is another method for eliminating cracks. At the beginning of work, the crack is sawed 25-50 mm deep and 10-20 mm wide. Excess concrete must be removed and the crack must be blown out of dust and dirt. The cut is filled with repair mixture. If the concrete crumbles, it is worth using a higher quality mixture; if it produces virtually no dust, a cheaper product will do.
To repair cracks, you can use the following mixtures: “LAKHTA basic repair composition” (cost - 57 rubles / kg), BASF MasterEmaco S 488 (33 rubles / kg), Sika Monotop 612 (86 rubles / kg).
Comparative table of technical characteristics of dry repair mixtures:
| Options | "LAKHTA basic repair composition" | BASF MasterEmaco S 488 | Sika Monotop 612 |
| Material consumption, kg/dm 3 | 1,6-1,7 | 1,9 | 2,11 |
| Water consumption, l/kg | 0,13 | 0,145-1,6 | 0,1-0,115 |
| Strength of adhesion to concrete after 28 days, MPa, not less | 1,5 | 2,5 | 1,5-2,5 |
| Bending strength after 28 days, MPa, not less | 8 | 8 | 7-9 |
| Waterproof grade no less | W12 | W16 | W16 |
| Application temperature, °C | from +5 to +35 | from +5 to +50 | from +5 to +35 |
| Cost, rub./kg | 57 | 33 | 86 |
Basic specifications presented in this table will help you choose best option repair mixture for your needs.
The right mixture for concrete repair and quality work guarantee an excellent final result.
Andrey Badovsky, rmnt.ru