How and with what to repair a concrete surface

Concrete is a strong and adaptable material that is used for many different types of construction projects, including floors, patios, and foundations. Even the hardest concrete surfaces, nevertheless, are susceptible to chips, cracks, and other kinds of damage over time. By taking quick action to resolve these problems, you can keep your concrete from deteriorating further and increase its lifespan.

Although fixing a concrete surface can seem difficult, most homeowners can handle it with the right equipment and supplies. To select the best repair technique, it is important to comprehend the kind and degree of the damage. There are easy ways to repair larger damage areas or small cracks in your concrete and bring it back to its original look and functionality.

We’ll walk you through the process of fixing a concrete surface in this post, outlining the supplies and equipment needed for each kind of fix. You will discover how to effectively address a variety of problems, from basic crack fillers to more complex resurfacing techniques. You can restore the original beauty of your concrete surfaces with minimal work and the appropriate method.

Repair Method Materials Needed
Crack Filling Concrete filler, caulk gun, putty knife
Resurfacing Concrete resurfacer, trowel, squeegee
Patching Concrete patch mix, water, mixing bucket
Leveling Self-leveling compound, primer, spreader
Spalling Repair Repair mortar, bonding agent, finishing trowel
Reinforcing Steel rebar, wire mesh, epoxy

What are the types of concrete damage and its causes?

You must be aware of the characteristics and makeup of concrete in order to comprehend the sources of damage. Sand, water, and cement are used to prepare it. I use crushed stone as a filler and use specialty additives like fiberglass and plasticizer to enhance performance characteristics. The concrete structure is reinforced with reinforcement for strength.

In other words, the solution contracts as it hardens. The resultant artificial stone is not resistant to tension, but it is strong in compression. Defects arise when such forces are applied to it while it is operating.

Damage may occur in any of the following ways:

  1. Loosening the overall structure. Defects may not be visible visually, but minor damage reduces the strength of the concrete structure.
  2. Surface destruction. The defect appears on the upper layers of concrete in the form of chips, potholes.
  3. Destruction of deep layers. The defect is manifested by cracks that form in loose areas of the concrete structure.

In general, two factors contribute to the destructive process of concrete: a breach in the technology used in its production and aging. Regarding the first factor, there are no queries. The quality of the concrete structure will be comparable if the solution is made incorrectly.

Regarding old age, the following elements affect how quickly the process moves along:

  • excessive mechanical loads;
  • exposure to chemicals;
  • increase in physical processes caused by thermal expansion;
  • corrosion of the reinforcing frame.

It is crucial to fix the old concrete as soon as the first signs of damage are noticed in order to stop more damage from occurring.

Repair compounds for concrete

For artificial stone restoration to be successful, a detailed examination and analysis of the damaged structure must be done prior to selecting a repair composition. The following considerations are made when choosing the mixture:

  • the degree of loading of the structure, its load-bearing capacity;
  • the depth of damage;
  • the conditions of concrete operation (humid environment, temperature conditions, the degree of exposure to aggressive environments);
  • accessibility to the damaged area;
  • the expected volume of work.

It’s crucial to consider aesthetic standards when fixing a concrete surface that will be visible.

Repair of large damages

Fresh concrete mortar is used to fill in a sizable damaged area. The structure’s surface is first cleared of dust and peeled pieces. A sound, clean foundation made of high-grade concrete is required.

A cement composition with sophisticated additives is used for the filling, which enhances the material’s performance properties. Fiber concrete or a quick-hardening polymer solution yield good results.

Establishing conditions for cement mortar’s dependable adhesion to the restored base is critical for the successful repair of concrete. Two approaches are typically used:

  1. The entire area of ​​the structure is continuously filled with a solution more than 100 mm thick. If partial restoration is carried out, the concreting area is deepened.
  2. The best adhesion of old and new layers occurs when the steel reinforcement mesh is fastened to the restored base with dowels.

The surface of the structure that needs to be repaired is coated with epoxy, acrylic, or other adhesive compositions that offer improved adhesion before the solution is poured.

Dry mixes for concrete repair

Cement is a component of all dry mixes for concrete repair, ensuring the best possible compatibility with the concrete structure being repaired. On the construction market, there are numerous compositions from various companies.

The two most well-known manufacturers are Osnovit and Knauf.

On both horizontal and vertical bases, a layer of the repair composition, 5 to 50 mm thick, is applied. A mixture thickness of 30 mm is ideal for restoring the ceiling. Pretreating concrete with a primer or primers ensures better adhesion.

The following categories of dry mixtures are separated based on the type of application:

  • for work at temperatures above +5°C;
  • at negative temperatures;
  • for waterproofing and providing protective properties;
  • for repairs that do not change the geometry and load-bearing capacity of the concrete structure.

Dry mixtures can be used anywhere rapid defect elimination and repairs are needed.

  • good adhesion to the old base;
  • high mechanical strength of the frozen composition;
  • due to additives, the mixture does not shrink;
  • possibility of eliminating defects up to 100 mm deep.

The short shelf life and high cost are the drawbacks.

Thixotropic mixtures

These are essentially better versions of traditional dry mix analogues. Well-known producers include Sika, BASF, and MAPEI. For concrete repair, a thixotropic composition consisting of cement, sand, and complex additives is used. Polymer fiber mixes are thought to be the most efficient.

Thixotropic compositions are applied on a horizontal, vertical, or ceiling surface without the need for formwork, in contrast to conventional dry mixes.

The ideal range for layer thickness is 10 to 30 mm. The mixture is used to restore protective layers, seal joints, and repair monolithic and precast concrete structures.

  • resistance to mechanical stress, abrasion;
  • good adhesion to the base;
  • resistance of the cured composition to moisture, low temperatures.

The expensive price and inability to operate in extremely cold temperatures are the drawbacks.

Epoxy and polymer compositions

The primary goals of the compositions are to organize the protection of a concrete structure from damaging factors, repair self-leveling floors, and perform injection work. Well-known producers include "Elakor," "Technoplast," and "KrasKO."

Concrete cracks can be fixed with acrylate compounds, which can also be used to seal chips and treat the base to increase water resistance. Epoxy mixtures help seal cracks and help artificial stone regain its bearing capacity.

Occasionally, the composition is used to increase the base’s adherence to a fresh layer of repair. Combinations of polyurethane stop leaks and stop water from entering.

  • resistance to mechanical and chemical influences;
  • good wear resistance;
  • high adhesion to the base;
  • good waterproofing properties.

A disadvantage is a short service life.

Repair work technology

Generally speaking, the following actions form the basis of repair technology:

  • preparation of the base for restoration;
  • installation of formwork and moistening of the base (if necessary);
  • preparation of the solution;
  • application of the mixture for concrete repair to the base to be restored.

Next is keeping the area that has been restored maintained.

Preparatory work

The following procedures are used to get the concrete structure ready for restoration:

  1. Mechanical preparation involves the use of a chisel, hammer, drill, or other tool that helps remove unreliable areas of concrete.
  2. Thermal preparation is based on heating the surface of the concrete base with a burner to a temperature of 90 ° C. Firing removes contaminants from artificial stone. Thermal preparation is followed by mechanical or hydraulic preparation.
  3. Chemical preparation involves treating the base with reagents, used where mechanical methods cannot be used.
  4. Hydraulic preparation is based on the use of equipment that creates high pressure up to 120 MPa. The method is used wherever it is safe to increase air humidity.

The removal of concrete damage is the aim of preparation. Making a sample of a layer that is at least 100–150 mm wide and up to 20 mm deep is ideal.

Preparation of the solution

Water is added to the mixture to dilute its dry composition for concrete repair. For large quantities, it is best to use a concrete mixer; for smaller batches, an attachment-equipped drill works well. The instructions will specify how much water to add, but generally speaking, 1 kg of powder is mixed with 0.13 l of liquid.

The components must be mixed in a clean container in order to prepare the composite, sealing, and injection compounds. The instructions provide similar details regarding the proportions.

Every solution’s necessary quantity is calculated with its service life in mind.

Elimination of a large defect using formwork

When fixing significant flaws that builders have left behind, the action is required. Boards and plywood are used to make formwork, and long sections are strengthened with supports to keep them from sagging.

A primer is applied to the base. After manually applying the concrete mortar, it is vibrator-compacted until cement milk forms on the surface. After the cement has completely hardened, a film covering the cemented surface is removed, along with the formwork.

The excess protrusions that result are removed, and the technological gaps are filled in with an injection process.

Repair with composite compounds

When strengthening a structure without adding weight or altering its geometry is required, the technology is applied. The base is first prepared using a grinder or sandblasting, after which an epoxy primer is applied and allowed to dry for up to 12 hours.

Applying the liquid mixture requires using a brush or roller. A trowel or rule is used to level any sand that may be present in the composite composition. The repaired surface is sanded after the epoxy resin has hardened and is rolled on to seal the pores.

Elimination of cracks with a liquid composition, seal and injection

Crack repair is done after waterproofing is restored, the base is fully dried, and the causes of the cracks are removed.

The approach is determined by how deep the defect is:

  • Small web-like cracks are eliminated by applying liquid compositions that form a protective coating.
  • Deep cracks are widened on both sides to approximately 150-200 mm, deepened to 50-70 mm. Dust is blown out of the grooves with a compressor, a polymer composition is injected or a seal is placed, filling the voids with fiber concrete.

The size of the crack determines the injection mixture’s composition and method of delivery. A pneumatic injector generates a pressure of 0.2–0.3 MPa to fill small grooves. Using a hand pump and packers, the composition is injected into cracks that are 450 mm deep.

Although it can be raised to 40 Bar during the procedure, the operating pressure is kept at 20 Bar. Until the mixture exits the neighboring packer that is installed in the crack, it is supplied.

Large cracks are filled in with anchors, and the entire base is covered in a 20 mm-thick layer of mortar following the injection of the channels.

Thixotropic torquetting method

After preparation, the base needs to have a rough texture for thixotropic mixtures to stick to it firmly. When the concrete surface gets wet, it is heavily saturated with water and covered in soil.

Thixotropic concrete repair is done by hand in small spaces. Utilizing a spatula, trowel, or trowel, the mixture is applied. The gunning method is used on large areas. Pneumatic concrete pumps or compressed air are used to supply the thixotropic mixture.

Applying a layer as thick as 30 mm is one cycle. Over the repaired base, the mixture is leveled. The project determines both the quantity and thickness of the layers.

Conclusion

In order to repair concrete structures, stepladders, ladders, and scaffolding are used. Workers wear safety belts when operating at heights. Both SNiP 12-03-2001 and SNiP 12-04-2002 include safety standards.

Concrete surface repair may seem like an overwhelming task, but it is doable with the correct equipment and methods. Your concrete will last longer and look better if you take the time to properly address any problems, no matter how minor they may be or how serious they may be.

To start, evaluate the damage to decide on the best course of action. A basic patching compound is often sufficient for small cracks. A more durable repair technique, like employing a concrete mix that can fill and bond the damaged areas, might be required for larger cracks and holes. To guarantee good adhesion, the surface must be properly cleaned before beginning any repairs.

When choosing supplies, go for items made especially for fixing concrete. These substances are designed to withstand the particular pressures and circumstances that concrete surfaces encounter. For optimal results, mix and apply according to the manufacturer’s instructions.

Lastly, before reusing the repaired area, don’t forget to give it enough time to dry and cure. If this process is rushed, the repair’s longevity may suffer. Your concrete surface can be brought back to a functional and aesthetically pleasing state with time and careful attention to detail.

When repairing a concrete surface, one must determine the kind and degree of damage, thoroughly clean the affected area, and choose the appropriate repair materials, such as epoxy, polyurethane, or concrete patching compounds. It’s crucial to use the right application methods to guarantee a seamless and long-lasting repair. The correct materials and techniques can be used to repair cracks, spalling, or surface deterioration while preserving the strength and aesthetics of the concrete. This will prolong its life and keep it functional.

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Anna Vasilieva

Journalist with a technical education, specializing in construction topics. I can explain complex technical topics in simple and accessible language.

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