Dry repair mixes for concrete. Repair mix for concrete: overview, characteristics, application Mix for repairing concrete surfaces

Sika manufactures repair mortars for concrete, buildings and structures of any type, including bridges, pipes, waterworks, residential and public buildings.

Reasons for the destruction of concrete

Despite all its strength, like all building materials, artificial concrete stone is subject to destruction under the influence of a number of external factors.

External static and shock influences can lead to the formation of shells, chips and cracks. Cycles of freezing and thawing provoke peeling of the front layers of concrete structures. Corrosion of steel reinforcement caused by exposure to chlorides, carbonization or other factors leads to an increase in internal stresses in the protective layer of concrete, which in turn causes cracks and bare reinforcement.

In addition, concrete stone is also subject to biological corrosion caused by the vital activity of microorganisms, fungi, algae and moss.

As a result of all these negative impacts, the bearing capacity decreases and the service life of the reinforced concrete structure is reduced.

How to choose mixes for concrete repair

The complex structure and low maintainability of concrete impose increased requirements on the compositions for the repair of reinforced concrete structures.

Compositions for concrete repair must have:

• high mobility to fill all cavities in a defective structure,
• high strength,
• high adhesion even without the use of adhesive compounds,
• high brand for water resistance and frost resistance,
• low shrinkage
• resistance to carbonation.

All these requirements are met only by specialized repair mortars for the restoration of concrete structures that meet the requirements of GOST R 56378. These materials include one-component cement mortars and corresponding to the class R4 and R3.

Technology of repair of reinforced concrete structures by pouring into the formwork

One of the main ways to repair concrete and reinforced concrete structures with a high degree of destruction - from 40 mm and above - is the method of pouring into the formwork.

Before pouring the repair mortar, concrete surfaces must be carefully prepared. Peeling, weak and damaged concrete must be removed, and a strong and rough concrete base must be moistened. The surface of the formwork is coated with a lubricant that reduces the absorption of moisture from the solution and facilitates its dismantling.

Ready mortar is poured into the formwork continuously without the use of vibrators.

Dry mixes for the repair of reinforced concrete structures by pouring into the formwork

Sika manufactures cement-based ready mixes for the structural repair of concrete and reinforced concrete.

structures. Corresponds to class R3 according to GOST R 56378.

One-component cement-based mortar

self-leveling type, designed for structural repair of reinforced concrete

structures. Corresponds to class R4 according to GOST R 56378.

Among the features of structural repair mortars are low shrinkage, the possibility of manual and mechanized application, high strength, adhesion and frost resistance.

Comments:

Both old houses and new buildings often require concrete repairs. Cracks on it may appear due to non-compliance with the filling technology, and sometimes from old age. Almost all concrete and reinforced concrete structures shrink and shrink when dried, and such a property of concrete as a low tensile strength contributes to the appearance of defects.

Cracks in concrete occur due to non-compliance with the rules of pouring, and sometimes from old age.

In addition, cracks in concrete appear:

• in case of mechanical damage to the material (accidents, excessive loads, vibrations, seismic activity, water wear);
• due to chemical damage (exposure to alkalis, salts and acids);
• due to physical processes (liquid leakage, temperature changes, erosion);
• against corrosion of fittings caused by carbonization, exposure to salts, humidity or carbon dioxide.

Regardless of the nature of the damage, they are subject to immediate liquidation, because. serve as a source of further destruction of the concrete surface. Do not despair, all the work can be done by hand.

Repair mortars for concrete and their application

Before starting work, you need to visually inspect the damage and choose the right method of repair and select the necessary components. Repair compounds for concrete should be selected taking into account the operating conditions of concrete structures (weather conditions, frequent exposure to chemicals and detergents, temperature conditions). Experts recommend repairing concrete surfaces using mixtures of a domestic manufacturer, since their composition is designed taking into account the weather and climatic conditions of our country.

As a rule, before applying the repair composition, it is required to moisten the surface well.

The quality and cost of repair mixtures depend on the presence of such properties as the ability to quickly thicken, high adhesiveness (the ability to firmly adhere to the surface), thixotropy (an increase in the viscosity of the composition that does not experience mechanical stress).

High-quality repair mixes for concrete contain polymer fibers and fine-grained filler, which make it possible to increase the thickness of the pouring layer up to 100 mm, reduce consumption by up to 10%, and prevent further delamination. They have anti-corrosion properties for reinforcement, resistance to the aggressive influence of salts and sulfates.

All compositions for concrete repair are conditionally divided into 2 main categories: self-leveling (casting), used for horizontal concrete coating, and thixotropic, suitable for vertical concrete walls and structures, ceiling surfaces without formwork.

Non-shrinking concrete mixes have an interesting feature - they are absolutely waterproofed thanks to specific additives added at the factory. A monolithic structure filled in this way will last not 20-25 years, but at least 50.

It does not react to moisture and liquid and, in addition, has some elasticity and additional physical resistance to mechanical stress. Non-shrinking concrete mixes come in different types. Some are designed for construction, others are fundamentally for repair work. When applied, they perfectly set, and after hardening do not differ from the original surface. It should be borne in mind that the repair of concrete of a large area (more than 5 m²) must be carried out using reinforcement, which further strengthens the structure. It is necessary to fasten the reinforcing mesh only on dowels, otherwise the result of the work may come out unexpected.

Concrete structures that experience significant loads may have an insufficiently strong surface (screeds, floor slabs and other monolithic structures). They can be reinforced with a deep penetration primer. During repairs, exposed reinforcement may be found, which must be treated with an anti-corrosion primer. Restoration of concrete in particularly critical areas must be carried out using special mixtures for quick repair, which contain fiber that improves the reinforcing characteristics of the composition.

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How to make a concrete repair compound yourself?

With a small area of ​​damage, you can make a repair compound for concrete with your own hands. It includes:

1. Cement.
2. Quartz sand.
3. Small gravel.
4. Ground limestone.
5. Fiberglass polypropylene.
6. A complex of modifying additives, the composition of which depends on the characteristics of the old concrete and operating conditions. These can be regulators of rheological properties, processes of setting and hardening, special purpose (frost resistance, moisture resistance, heat resistance), polyfunctional action.
7. Water.

In the simplest version, the ratio of cement: sand: crushed stone: water is taken as 1: 2: 3: 0.8 (when kneading by hand, more water will be required).

It is preferable to use a table of component ratios (Fig. 1), since in order to obtain concrete of a higher or lower grade, it is necessary to change the ratio of all components. The dosage of modifying additives is indicated on the packaging and usually does not exceed 1% of the volume of cement.

Figure 1. Table of component ratios for concrete repair.

All dry ingredients must be mixed. After it, pour the required amount of clean water into an empty container and add the loose composition to it, constantly stirring the mixture. To form a homogeneous mass, it is desirable to use a perforator with a mixer attachment. If concrete repair is carried out in hot weather with low air humidity, the volume of water can be increased by 2-3%. If the temperature is below +5 degrees, then water with a temperature of 30-40 degrees is used to prepare the solution.

Mixing the dry mixture with water must be carried out for at least 4 minutes. The prepared solution should be used up within 1 hour.

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Foundation preparation

Restoration of concrete should begin with high-quality preparation of the base. Initially, dust, dirt, remnants of old paintwork, etc. must be removed from the surface. Damaged concrete layer must be beaten off and completely removed. The work area must be completely degreased, oil contamination should be removed with a solvent. Exposed reinforcement must be cleaned of corrosion.

If the repair of concrete structures is carried out at positive temperatures, the surface is thoroughly moistened with a wet rag. You can use a hydrojet. In cold weather, it is not necessary to moisten the surface, but snow and ice must be removed with a burner.

Next, the wetted surface must be primed with a solution with a high adhesive content. The mortar layer should be 1-3 mm thick. Especially carefully it is necessary to coat the cracks and recesses with a primer and process the bare reinforcement. This will not only improve adhesion, but also provide additional anti-corrosion protection. In frost, it is not necessary to prime the surface.

Concrete repair technology often becomes the only effective way to restore the coating of building structures, concrete blocks, pillars, flights of stairs, slabs and areas of knocked down concrete pavement at the entrance to the house at minimal cost. Timely restoration of the chipped part of the surface with a special mixture, at least, prolongs the life of the steps or structures.

Difficulties in the concrete repair process

Concrete repair has to be resorted to in a situation where the reinforcement is opened, or the spilled concrete crumb opens the crushed stone filler of the slab, steps or sidewalk. In any case, if urgent measures are not taken and concrete repairs are not made, the matter will end in injury or the collapse of the building.

It is very difficult to repair with a conventional cement-sand mixture due to two fundamental qualities of concrete:

• The dense structure of the cement grain practically does not absorb aqueous solutions, so the usual masonry mixture almost does not stick to concrete;
• A thin layer of repair mixture based on liquid concrete shrinks, peels off, and, as a result, repair with a conventional mortar ends with chipping of the laid layer.

Therefore, to restore concrete chips and wear, special repair mixes for concrete are used. Due to special additives, the concrete repair compound retains plasticity, strength and high adhesion to a dusty concrete base.

To restore concrete, repair mixtures are used based on three basic compositions:

• Polymer-cement dry and ready mixes;
• Fibropolymer compounds based on sand, cement and acrylic binder;
• Compositions based on epoxy resins.

Not all repair mixtures are the same; for each specific case, its own composition is used, which is best suited to restore the original characteristics.

What should be the mixture for repair work

All high-quality compounds used for repair work with concrete cavities and chips have the same general properties:

• The repair mixture before laying on concrete has a high viscosity;
• Thixotropy of the repair composition;
• High fluidity and fine composition;
• The presence of organic substances that remove air microbubbles and effectively wet dusty surfaces;
• No shrinkage and extremely fast hardening.

Why is it impossible to fill a chip or pothole in concrete with masonry cement-sand mortar? You can, most negligent builders do just that. As a result, if the mix is ​​too thin, the repair patch will shrink and have low strength, and if the repair is to be done on vertical or inclined surfaces, the mix will simply flow out of the mould.

If you knead a thick mortar, then the repair mass will not really stick to the chipped concrete, a mass of air bubbles will remain on the contact surface, and after a couple of months the patch will fall off.

The repair mass must have good thixotropic characteristics. When poured, such a mixture behaves like a liquid pouring cement-sand mortar used to strengthen the gravel blind area of ​​\u200b\u200bthe foundation. Thanks to special additives, the repair mixture penetrates into all microcracks, chips and cavities on the concrete surface. The adhesion of the material to concrete is 2-3 times higher than that of a conventional masonry mixture.

After pouring into the mold, the process of self-compacting and displacement of excess water from the solution begins almost immediately. After a short period of time, the water leaves, and the repair patch turns into a dense and at the same time viscous mixture, securely held in the damaged area.

Materials for the repair of concrete surfaces

Most repair mortars available on the market for the average consumer can be divided into four main categories:

• Materials for the restoration of high-strength loaded structures made of concrete;
• Repair mixes with increased resistance to abrasion load;
• Insulating compounds, in addition to restoring the lost part of the surface, the mixture must reliably protect the internal structure from the penetration of moisture and air;
• Universal sand-cement compositions used for sealing small damages and manufacturing defects.

The price of repair materials directly depends on its composition. The most expensive two-component finished masses based on epoxy resins can cost several thousand rubles per package. Whereas the repair mix for concrete Ceresit 83 costs 500-700 rubles. per pack of 25 kg.

Repair mixes Ceresit

The most famous repair mixture is rightfully considered the finished mass of Ceresit 83. It is Knauf's products that most often repair chipped and crumbling parts of porches, steps, flights of stairs, canopies and parts of balconies. Ceresit TsN 83 is recommended for repair work on unloaded concrete structures and for pouring floor screed. Ceresite can be poured into concrete damage only in cases where the destruction process is blocked and stopped, there are no signs of cracks and chips.

The material is produced on the basis of fine sand, high-strength cement and water-dispersed polymer additives.

Before laying the repair mixture, the concrete surface must be pre-cleaned of any dirt, traces of paint and oil. If there are cracks on the repaired surface, they must be expanded and cleaned of dust with a stream of compressed air.

In the case of repair work on chips of especially dense concrete, it is recommended to pre-prime the surface with a mixture from the proportion: 3 parts of water and 5 parts of CH 83 are taken for 1 part of CH 17. You can step on the patch after six hours, complete curing occurs after three days.

Mix for repair work Penetron M500 Skrepa

Of the dry repair mixes of Russian production, one can single out the products of the Penetron "Skrepa" company. The recipe for the preparation of a dry mix for repair work on concrete includes:

• Finely dispersed quartz sand, which has undergone special processing;
• High-strength Portland cement M500 with extra fine grain;
• Polymer additives that improve the fluidity of the repair mixture;
• Mineral fibre.

The dry powder is mixed with water in proportions: 170 ml of water per 1 kg of the mixture. The material is prepared and laid at a temperature not lower than +5 ° C. Before pouring the repair mixture on the damaged areas of concrete, the surface is washed and saturated with water to the maximum achievable limit.

With an optimum consumption of 1.8 kg per square, a layer thickness of 1 mm is achieved. For one laying, it is possible to form a repair patch with a thickness of 5 to 35 mm. The next layer can be laid after four hours. Tack-free setting time - 10 minutes, setting with a set of preliminary strength levels is 120-150 minutes, depending on the air temperature.

After 28 days, the repair patch acquires a water resistance index of W14, with a strength of 50 MPa and adhesion of 1.3 MPa.

Mixes for repair work of the trade mark Parade

For situations where urgent repair work is required, it is possible to offer the use of concrete mixes produced by the Belarusian company Parade. The manufacturer positions its products as an effective material for winter work;

The first and main advantage of the Belarusian cement-sand "repairman" is the high setting speed and the enormous strength of the filled patch. Already after 24 hours the static strength of the concreting layer is 20 MPa, after a month the strength increases to 70 MPa, with frost resistance class F200.

Note! Despite a significant amount of additives and mortar delamination stabilizers, PC516 is allowed to be used for casting and repairing potable water tanks.

The scope of PC516 covers the entire range of repair of building structures made of concrete, from grouting the foundations of buildings, concreting anchors, driving joints in prefabricated structures, hydraulic and road structures. According to road services, RS516 is successfully used for high-quality patching of asphalt concrete roads.

The only drawback is its high cost, at least 4000 rubles. per pack of 25 kg.

Imported repair mixes

To repair complex structures made of concrete, subject to significant deformations and deflections, high-strength patches made of cement-polymer mixtures filled with elastic metal fibers are most often used. For example, the highly thixotropic mass Mapegrout MF, manufactured by the Italian company Mapei, can be used.

The repair material is used primarily for the restoration of vertical concrete surfaces without additional formwork and shotcrete. Italian concrete, even after full curing, retains high plasticity, so there is no danger of developing fatigue stresses and rebounding of the patch from the base.

Mapei's products can even repair rebars that have been exposed from under concrete. Provided that the degree of corrosion damage is not more than 15% of the exposed metal.

The price per package is 1300-1500 rubles.

For less loaded building structures made of concrete, you can use the Vimacret cement-sand mass, manufactured by the Greek company Vimatec. The strength and wear resistance of the hardened patch approximately corresponds to the characteristics of Ceresit 83, but the plasticity and moisture resistance are not inferior to PC516 and Mapegrout.

The use of Vimacret is aimed at the arrangement of water conduits and sanitary hydraulic structures. A distinctive feature of the material is its resistance to the formation of fine hairline cracks. Vimacret is successfully used for casting tanks, conduits, repairing slabs and voids in castings, plastering and skirting boards in entrances, gluing lining and tiles on porch steps.

The practice of using repair mixes for concrete

Proper use of repair mortars for concrete provides for the fulfillment of three conditions:

The material can be applied by pouring with obligatory compaction with a vibrator or by gunning the surface from a manual apparatus. When carrying out restoration work on vertical and ceiling surfaces, the overspending of the mixture increases by 20-30%.

Conclusion

The use of repair mixes for concrete allows solving two complex problems at the same time - to restore the bearing capacity of concrete structures and save huge amounts of money for their overhaul. Most patches laid in compliance with the repair technology can last at least 30-40 years.

Concrete is a material used in all areas of construction, the main advantages of which are high strength, reliability and durability. But over time, even concrete structures are destroyed. There can be several reasons for the appearance of cracks, chips, deformations: violation of the ratio of elements during mixing, mechanical influences, environmental influences, loads, and so on. To restore the material, special mixtures are used.

Repair mixtures are used for quick restoration of various concrete structures, restoration of their geometric parameters and performance characteristics.

Repair compositions for concrete are of two types:

• casting;
• dry.

To fill pre-prepared cracks and recesses, casting mixes for concrete are used. They have the ability to expand and a high degree of adhesion to concrete, stone and reinforcement, and when solidified, they practically do not shrink. Filling all the free space, the solution reliably seals and strengthens the repaired surface. Casting mixtures are used in the restoration of horizontal surfaces.

Restoration of concrete and strengthening of monolithic structures is also carried out using dry compounds. A high level of frost resistance and strength allows the use of dry mixes for the repair of products exposed to the negative effects of natural phenomena and cyclic loads. Due to the good characteristics and moisture resistance of the hardened substance, concrete is often waterproofed with it. The material is completely non-toxic, so it is used, for example, to repair drinking water tanks.

Dry formulations are used:

• for the restoration of load-bearing surfaces, floors, stairs;
• for the restoration of roads;
• to protect concrete from corrosion.

The listed species are presented on the domestic market in a wide range. The cost depends on their quality, characteristics and manufacturer.

Overview of popular manufacturers

The requirements for casting and dry mixtures are as follows:

• high degree of adhesion with the restored surface (concrete, stone, rebar);
• exclusion of shrinkage.

Often the main aspect influencing the choice of the buyer is the price of the product. Especially if you need to purchase a large batch for concrete repair.

A brief overview of popular brands will help you make the right decision.

Emaco

The Russian company Basf manufactures and sells Emako compositions used to repair concrete damage of varying degrees of complexity: from small cracks to complex deformations.

• "Emako" N 5100 is used for the first degree of damage: the presence of dirt, cracks, shells.
• With the help of "Emaco" N 900, N 5200 damage of the second degree is repaired: crumbled or peeled off surface areas, as well as small chips.
• Emaco S 488 PG, S 488, S 5400 perfectly cope with rust and cracks up to 0.2 mm and a depth of not more than 40 mm (third degree).
• Cracks larger than 0.2 mm, bare reinforcement, a high level of carbonization - the fourth degree, depth up to 100 mm - are restored with Emako T1100 TIX, S 466, S560FR compositions.
• Heavily damaged concrete structures with bare reinforcement and chips more than 200 mm deep are restored using non-shrink (Emaco A 640) and anti-corrosion (Emaco Nanocrete AP) mixtures.

You can buy "Basf" on the official website of the company. The cost varies from 850 to 1700 rubles per package of 25 kg, depending on the components of the composition.

"Birss"

The mixture for the restoration of concrete bases "Birss" is produced in Russia and is designed to perform repairs of any degree of complexity.

• Birss 28, 29, 30, 30N - simple repair of cracks and flaky surfaces.
• Birss 30 C1, 58 C1, 59 C2 (restoring) are used in the second degree of deterioration of concrete.
• In the third degree of damage, the compositions "Birss" 59C3, 59 C are used.
• To correct larger defects, the following Birss mixtures are used: Concrete spatula, RBM or 600 VRS (non-shrinking).
• With the help of "Birss RSM" complex destruction of concrete structures is restored.

The frost resistance of Birss compositions allows repairs to be carried out at low temperatures. They have high adhesive strength, elasticity, density and water resistance.

The advantage of the material is the affordable cost: from 400 to 450 rubles per 50 kg.

Another representative of domestic production is the Bars Consolit repair mixture, which is excellent for the restoration of vertical and horizontal structures. Bars quickly gains the required strength and does not shrink. The mixture has a high level of adhesion to concrete.

There are bulk and thixotropic compositions. The former differ in the thickness of the applied layer, the angle of inclination of the surface to be repaired, and the cost. The price of bulk mixtures varies from 800 to 1,000 rubles per 30 kg.

Thixotropic solutions "Consolite Bars" are:

• reinforcing (113 V60);
• finishing (115 V50);
• repair non-shrink (111 V30).

A moisture-resistant coating is created with a mixture of "Consolit Bars 100", which has an expansion function.

The price varies from 900 to 1,500 rubles per 30 kg, depending on the components of the composition and the region of sale.

Ceresit CX5

Repair of concrete structures in conditions of high humidity is best carried out using a mixture of "Ceresit" ("Ceresit CX5"), which, when solidified, does not shrink and forms a moisture-resistant and frost-resistant coating that reliably covers all defects.

It costs "Ceresit", which has high technical characteristics, quite expensive - about 2,700 rubles per 25 kg.

"Knauf"

Concrete waterproofing is usually carried out with the Knauf Flahendicht mixture, which, in addition to leveling the surface, gives it moisture resistance and vapor permeability. The advantage of the composition is the absence of toxic additives and convenient packaging of 5-6 kg. The Knauf solution can be used both outside and inside the premises. Price - from 350 rubles per 5 kg.

"Found"

A novelty on the Russian market - "Founding Innoline NC60" from "INDASTRO". This is a grouting compound used to repair vertical and horizontal surfaces. The mixture is used not only for restoration work, but also for the installation of equipment on a concrete base. The mixture costs about 800 rubles for 25 kg.

With the help of the dry leveler "Osnovit Selform T-112" they repair floors and walls made of concrete of various types. It has a high level of adhesion and water-repellent properties. It costs from 160 rubles for 20 kg.

"Alit"

The composition of dry mixtures "Alit" (SDR-UR, SDR-U, SDR-UM) includes fine quartz sand, hydraulic binders and non-toxic polymer additives. The composition evens out large cracks and chips, with a depth of 2 to 20 mm, formed on concrete bases, load-bearing structures, stairs.

Possessing resistance to negative temperatures, "Alit" allows you to carry out repairs in the winter.

The price of the mixture is from 1,100 rubles per 25 kg.

mapei
Quick and convenient concrete repair is guaranteed by Mapei dry mix manufacturers. Solutions do not shrink during solidification, do not crack, exclude cavitation, erosion and abrasion. Repair compositions "Mapei" are presented on the Russian market in a large assortment:

High-strength material is used for floor restoration in industrial workshops, repair of airfield slabs, roads, canals and tunnels.

The cost of mixtures depends on the components included in the composition, and varies from 850 to 1,300 rubles per 25 kg.

SW

"SW" is a dry mix used for the repair of reinforced concrete products. The advantages of "SW" are resistance to adverse external factors: mechanical and dynamic loads, high and low temperatures. Moisture-resistant and durable composition is suitable for repair work as soon as possible. The solution, when solidified, forms an anti-corrosion protective coating and is an excellent waterproofing agent.

The price for 25 kg is from 240 to 260 rubles.

How to choose the right repair material

In order to choose the right mixture for concrete repair, it is necessary to follow a certain algorithm of actions.

• Determine the parameters of the repaired area: type of surface, amount of damage, load during operation.
• Choose the type of mixture: cast or dry.
• Select the type of mortar (good adhesion, fiber reinforced).
• Compare prices, mix components and choose a manufacturer.
• Calculate the amount of material needed to complete the work.

Before ordering and buying a mixture, you need to pay attention to the following characteristics:

• hardening time;
• mixture consumption per 1 m2;
• protective functions of the solution;
• shrinkage (you should choose non-shrink compositions).

The market offers a huge number of different repair compounds for the restoration of concrete structures that have lost their original characteristics. They differ from each other in composition, functionality, consumption, price, quantity in the package.

The right choice of repair mix guarantees many more years of safe service for concrete structures.

The cost of concrete repair mixes

Approximate prices for restoration compositions are shown in the table below.

Exposed concrete is subject to permanent exposure to snow, rain, sun. From season to season, structures experience temperature fluctuations, the magnitude of which can reach 100°C. Sadly, statistics show a very extensive experience of the fragility of the protection used.

Literally a year later, the seams and layers crack, leaks occur, and fluid accumulates in the protective layer. With the next freeze / thaw cycle, peeling of the finish coat may occur. Therefore, the most serious requirements are imposed on the complex of repair and restoration work.

Long downtime during concreting can cause poor setting of new and old concrete

Structures made on the basis of artificial stone are destroyed under the influence of the following factors:

• chemical reactions- arise due to an increase in the level of carbon in an artificial stone. They cause a violation of the proportions of the w/c ratio in the solution;
• chemical reactions that occur under the action of chloride ions. Chlorine is found in road salt, which affects reinforced concrete pavements. Reinforcement oxidation begins in the structure;
• moisture liquid is able to seep into the pores of concrete. At sub-zero temperatures, it crystallizes, which causes the destruction of concrete, cracking;
• mechanical loads- dynamic impacts, impacts exceeding the allowable loads work on the destruction of concrete;
• natural disasters, seismic activity, fires;
• carries a serious risk non-compliance with technological standards at the construction stage. Here we can talk about the formation of cold seams, which during operation damages the strength and aesthetics of the structure.

Purposes and methods of repairing concrete on the street

Repeated repairs carried out without observing the technology and with the participation of illiterately selected materials can lead to further degradation of the structure, loss of bearing capacity and significant financial costs.

Restoration of concrete structures should be well planned, taking into account the following goals:

• restoration of the bearing capacity of the structure;
• protection of fittings from corrosion;
• reinforcement of concrete by means of composite materials.

Repair steps can be summarized as follows:

• inspection of the concrete structure;
• identification of the causes that led to the destruction;
• planning of repair activities;
• selection of compositions and technologies;
• repair implementation;
• care;
• quality control.

Concrete floor repair materials

Objects can be industrial outdoor areas, beams, ceilings, roads and other surfaces that are subject to strong dynamic loads.

When choosing a material, the degree and nature of damage, the technical characteristics of concrete, and the specifics of operating conditions are always taken into account. It is necessary to monitor the compatibility of the repair composition and concrete, the degree of responsibility of the structure, the depth of destruction, the position and accessibility of the repaired surface.

Depending on the nature of the damage and the purpose of the repair, the following types of mixtures are used:

• repair compounds used to restore the bearing capacity of concrete structures;
• compositions for non-structural restoration. In this case, small defects are repaired and the surface is leveled.

In addition, it is customary to distinguish:

• compositions for anti-corrosion protection of fittings;
• materials for the repair of non-reinforced and reinforced concrete;
• waterproofing compounds;
• leveling compounds;
• epoxy resins for repairing cracks by injection;
• finishing protective and decorative coatings.

Thixotropic mixtures (materials for structural repairs)

These are dry mixes intended for the restoration of concrete and reinforced concrete structures on the street. The material is reinforced with polymer fiber and is characterized by compensated shrinkage. We can talk about a high degree of adhesion, water resistance, frost resistance, mechanical strength.

Thixotropic mixtures are applied manually or mechanically, in a layer of 10-35 mm. Thanks to its thixotropic characteristics, the working the solution works on vertical and horizontal bases, without requiring the use of stationary formwork.

Scope of application: mixtures are most often used for structural repairs (restoration of bearing capacity) of vertical and horizontal foundations, when smoothing open reinforcing bars, filling traces from formwork, repairing upper layers.

Fluid solutions

Scope of application: structural restoration of reinforced concrete columns, viaduct steps, floor slabs and beams, industrial floors, roads, filling gaps and cracks between slabs

These are dry mixes used for the repair of concrete by pouring into the formwork. This option is indispensable where, due to the specificity and depth of damage, a high fluidity of the solution is required. The material is used in the restoration of road surfaces, when filling areas between concrete structures, etc.

The thickness of the application layer is 10-40 mm. When mixing with water, a solution is formed that is resistant to abrasive loads, delamination, and low temperatures. Plus, waterproofing properties are realized.

Typical technical parameters

Solutions for the repair of concrete destroyed by corrosion of reinforcement

Such compositions are characterized by average strength and controlled shrinkage. They are used to repair concrete destroyed due to corrosion processes in reinforcement. Layer thickness 5-35 mm. Formwork is not required.

Solutions of this type can be applied to vertical surfaces. In order for all the properties of the material to be able to fully work on open concrete sites, it is recommended to use additional additives. The material is not suitable for structural repairs.

Scope of application: restoration of concrete destroyed by corrosion of reinforcement, balconies, beams, pillars, alignment of defects on vertical surfaces, in technological, rigid seams.

Typical Specifications

Compounds with fast curing

The aggregate size in grout mixtures can vary from 3 to 10 mm

These dry mixes not only quickly gain strength, but are also designed to eliminate serious defects. This is a good solution for heavily loaded bases where long downtimes are not possible (industrial facilities, roadways, runways, bridges). Some varieties can be used at low temperatures. Layer thickness 20-300 mm.

Gravy mixtures can be attributed to this group - they do not shrink and are characterized by rapid hardening. The material is necessary for high-precision grouting and installation of equipment, including outdoors.

Scope of application: repair of road, airfield pavements, where urgent work is required, repair of concrete industrial sites, filling of hard joints, installation of fences, concrete pillars.

Typical technical parameters

Anchor mixtures

It is a fluid, expanding concrete mix that quickly gains strength and is not subject to shrinkage. It is used for anchoring industrial equipment and fixing bases, filling technological cavities and seams.

Typical technical parameters

Injection solutions

To repair cracks, a cement binder can be used, on the basis of which an injection mortar is prepared.

The injection material is suitable for filling rigid joints, cavities, cracks, compacting foundations, strengthening structures

Typical technical parameters

Waterproofing materials

Compositions of this type are used for waterproofing and secondary protection of concrete structures.

The material can be divided into two groups:

• elastic compounds for protection against weathering and water load. These are ready-to-use two-component mixtures based on a special cement binder, synthetic polymers, and additives. After curing, a waterproof elastic layer with high adhesion is formed. The optimal application thickness is 2 mm;
• rigid waterproofing to protect structures in case of negative and positive water pressure. These are ready-to-use one-component mortars based on cement binder, fine sand, and additives. After mixing, a plastic solution is formed. In the cured state, a tough waterproof layer with high adhesion is formed. The optimal application thickness is 2-4 mm.

Typical specifications:

Rigid waterproofing layer is able to withstand pressure up to 1 atm

Equipment, tools and equipment

Professional equipment and tools are required at every stage of repair and restoration work.

A typical set that should be on site:

• base preparation equipment: in the open air, sandblasting or shot-blasting installations, high-pressure apparatuses (hydraulic installations), compressed air compressors are used. To connect the equipment, mobile power plants of the required capacity may be required. For jointing defects and cracks, perforators, jackhammers are used, the reinforcement is treated with metal brushes;
• equipment and tools for applying solutions: manual application may require spatulas, brushes, trowels. For mechanized application, shotcrete installations are used;
• equipment and tools for preparing solutions: concrete mixers are taken to work. You may also need a construction drill with a mixing nozzle, a shovel, a clean container, a measuring tool, devices for determining the viscosity of the solution and searching for reinforcement;
• means of individual protection, overalls.

Foundation preparation

The edges of defects, recesses are worked out with diamond disks, acting with the tool perpendicular to the surface. Work to a depth of at least 10 mm. With a needle gun or light perforators, concrete is selected from the defect.

The walls of the processing area must be vertical, the base itself rough and even. If the surface is smooth, create a roughness with recesses of at least 5 mm.

Concrete must be cleaned of cement laitance, paint, grease, oils. For final cleaning of the surface, compressed air of a compressor or high-pressure apparatus is used.

Surface cleaning can be implemented in several ways, depending on its actual state and working conditions:

• hydraulic method- the technology does not work in cases where it is required to exclude an increase in air humidity. Otherwise, it is a versatile and effective method that can be applied to almost any concrete;
• thermal- they work with burners when the concrete is heavily contaminated with petroleum products, rubber, oils. The method is effective at a small depth of damage (up to 5 mm). The heating of the base should not exceed 90 degrees;
• mechanical- one of the universal methods of preparation. Concrete is cleaned using sandblasting equipment, perforators, jackhammers, but mechanical processing is excluded where high dustiness should be avoided;
• chemical- an alternative to mechanical processing. The work site is treated with special compounds, after which it is washed with water.

Do not forget about cleaning the fittings from rust. To do this, use a metal brush to work manually or use a mechanized method (sandblasting).

With full exposure of steel, the gap between the surface and the rods should be at least 20 mm

If a thixotropic compound is applied, the prepared concrete must be damp. Excess liquid is removed with compressed air or a sponge. Good moisture should be achieved, but the substrate should not be wet.

Preparation of solutions

The technology of work depends on the type of mixture used. Of paramount importance is the amount of mixing water and the sequence of kneading.

Preparation of thixotropic solutions:

• for proper mixing of the working mixture, use the material in a whole container. The packaging is opened immediately before mixing;
• an accurately measured amount of water is poured into the concrete mixer (3.75 l - with manual application, 3.9 - with mechanical application);
• the mixer is switched on, after which the dry mixture is continuously introduced into it. The kneading lasts 1-2 minutes;
• the equipment stops for a minute, the walls are cleaned of adhering dry mixture;
• if required, water is introduced, not more than 200 ml;
• then kneading continues for 2-3 minutes until a solution with a homogeneous consistency is produced;
• if it is impossible to provide proper moisture care for concrete, it is recommended to introduce moisture-retaining additives. The amount is taken as 0.25 kg for every 100 kg of dry mix;
• if it is required to prepare a small amount of mortar, it is permissible to knead with a construction drill with a paddle nozzle. Thixotropic mixtures are not mixed by hand.

Preparation of flowable cement mortars:

• the working composition is prepared in a concrete mixer. Pour the required amount of water into the bowl of the equipment. To ensure medium fluidity, 3.6-3.7 liters of liquid per 25 kg of dry powder will be required, for highly fluid - take 3.8-4.0 liters per 25 kg;
• After adding water, the stirrer is started, the dry powder is continuously introduced. The kneading lasts 1-2 minutes;
• the finished mixture should be liquid, without lumps;
• It is permissible to use an electric drill with a nozzle. The composition is kneaded by hand in exceptional cases, prepared in small portions for 5-6 minutes.

Dry mixes for the repair of concrete affected by corrosion of reinforcement, fast curing compositions are prepared in an identical way

Preparation of injection solution:

• 6-6.4 l of water is poured into the concrete mixer and 20 kg of dry mix is ​​introduced. The solution is mixed for several minutes until a homogeneous fluid mass without lumps is formed.

Preparation of elastic waterproofing:

• liquid component B is poured into a clean container;
• component A is slowly poured and the mixture is kneaded with a construction low-speed mixer;
• the kneading lasts several minutes. Control the thoroughness of mixing at the bottom and walls of the container;
• waterproofing can be prepared in a concrete mixer equipped with mortar sprayers. With this method, you should make sure that the mixture is homogeneous and without lumps. So it will calmly pour into the sediment funnel.

If it is necessary to prepare a rigid waterproofing, water is added to a clean container, a dry mixture is introduced in portions. The composition is mixed with a low-speed mixer for 2-3 minutes. The material must stand for 10 minutes, after which it is re-mixed and goes to work.

Application of solutions

Repair of concrete structures can be carried out using special equipment or hand tools.

Application of thixotropic mortar:

• thixotropic mixtures are applied to vertical or horizontal structures by hand using a trowel or spatula. It is possible to involve a mechanized method with the help of special equipment (shotcrete installations);
• the allowable thickness of one layer is taken as 35 mm. The layer-by-layer exposure time should be 4 hours;
• before applying the material, the reinforcement must be cleaned and coated with an anti-corrosion compound;
• the temperature of the base during the repair should not be lower than +5 degrees. In case of rain and strong wind, the composition is not applied;
• average consumption - 19 kg of dry powder per m2 of surface when developing a layer of 1 cm;
• during the day, the repaired area is moistened.

Application of fluid solution:

• the finished solution is continuously poured into the formwork, the concrete is pre-impregnated with water. Formwork before starting work is treated with appropriate materials (lubricants) to prevent the absorption of water contained in the solution;
• in the process of pouring do not use vibrolaths, vibrators, etc.;
• the material must fill the entire volume of the formwork. If there are hard-to-reach places, the solution is applied there manually;
• in hot weather, cold water is used to prepare the mixture, the filling is protected from solar radiation. Average consumption - 20 kg / m2 per 1 cm layer.

The use of mortars with a rapid set of strength:

• the prepared material is poured onto the prepared surface without the use of vibration;
• the composition is evenly distributed over the entire area of ​​\u200b\u200bthe repaired area with the help of a trowel, spatula, trowel. Smoothing is carried out immediately after leveling.

The internal parts of the formwork are treated with grease for subsequent easy dismantling

If the solution is poured into the formwork, it is continuously fed from the selected side (it must be one). This will help prevent air entrapment. Surface care is required within 24 hours.

Application of injection solution:

• make sure that the base is structurally resistant to injection pressure. Otherwise, it is required to strengthen the concrete;
• the solution is introduced under a pressure of 1-2 atm, through pre-installed packers (tubes);
• work begins with the lower packer, gradually moving up until all defects are filled. Typical consumption is 1.6 kg to fill a cavity with a volume of 1 liter.

Application of elastic waterproofing:

• after preparation, the solution must be applied within 1 hour;
• if manual application is intended, spread the material with a smooth spatula. The second layer is applied on top of the fresh first layer. The thickness of the two-layer system should not exceed 2 mm;
• with a large amount of work, the composition is applied by spraying;
• if it is required to waterproof critical structures (intense loads), a fiberglass reinforcing mesh is pressed into the fresh layer. After that, the surface is leveled and after 4-5 hours a second layer is applied.

Rigid waterproofing is applied by spraying, brushing or spatula. If a brush is used, 2-3 layers are implemented in compliance with layer-by-layer drying (5-6 hours). When using a spatula, it is still recommended to apply the first layer with a brush.

When spraying, the waterproofing is applied in two layers, after waiting for the partial hardening of the first. The final thickness of the coating should be 2-3 mm. In windy and hot weather, the base is protected from the rapid evaporation of moisture with a polyethylene film.

Reinforcement corrosion protection

Reinforcement bars must be cleaned of corrosion. In the course of the work, the possibility of applying an anti-corrosion compound to the rear side of the reinforcement is evaluated. When preparing a working solution, the amount of water used is controlled. The thickness of the applied layer is measured with a caliper (before and after application).

When the reinforcement is processed, a solution with anti-corrosion properties is applied. Application on vertical surfaces is carried out manually using a spatula or trowel. The maximum layer thickness is 35 mm. Mechanized technology with the help of special equipment is acceptable. The exposure time of each layer is 4 hours.

Repair of concrete floor screed

To restore such bases, thixotropic solutions are successfully used. With their help, you can eliminate minor defects, large cracks, and carry out major repairs. The principles of surface preparation and solution preparation remain typical. Before repairing defects or pouring a new screed with a thixotropic mixture, priming is carried out.

Quality control

After the repair and restoration work is completed, quality control is carried out, for which special equipment and visual inspection are used. Most often, structures are checked by mechanical means: adhesion meters, sclerometers, hammers, devices that determine the quality of the floor screed.

After measurements, the obtained characteristics are compared with regulatory documents

Safety precautions when repairing concrete on the street

Persons of full age (18+) are allowed to carry out the work. All workers must undergo appropriate instruction, medical examination and training. Provision of personal protective equipment is required. Repair compounds may cause irritation on contact with skin and mucous membranes. If such contact occurs, the affected area is abundantly cleansed with water and medical attention is sought.

The cost of work

The average financial costs for the restoration of structures for various purposes start from 2.5 tr. per cubic meter. This price includes preliminary preparation of the bases, the main stage of work and maintenance.

findings

The choice of material for the repair of artificial stone should have an integrated approach. The use of a particular technology depends on the operational characteristics of the bases, the condition of the concrete, and the degree of its damage.

Modern cement mixes, with which the market is so filled, are considered a universal solution for the repair and restoration of concrete structures. Thixotropic compositions have successfully proven themselves in restoring the bearing capacity of even the most critical objects.

Flowable, anchoring and fast-setting mortars are used in any repair practice for leveling and sealing damage on concrete that is not subject to high loads.

An example of repairing concrete structures on the street is shown in the video: