Concrete is a versatile building material. It has unique strength characteristics and is used for the construction of buildings and structures in industrial and civil engineering. Concrete structures, although they are durable products, they also begin to collapse under the influence of various loads and as a result of atmospheric influence. The process of destruction of concrete substrates begins with the appearance of cracks and chips, and therefore the timely elimination of these problems will significantly increase the service life of the structure.
Deformation of concrete products occurs for the following reasons:
- change in the characteristics of the material in connection with shrinkage processes;
- mechanical impact;
- sudden changes in temperature;
- corrosion of internal fittings.
To make repairs with your own hands at various objects (garage, industrial buildings, utility rooms, apartment, country house, cottage), use the following compounds:
- DSP, to remove small cracks;
- mixtures of which epoxy resin is included;
- sealants and self-expanding linear products;
- solutions with the addition of water glass;
- ready mixes for construction and finishing works.
Epoxy resin
Repair compositions for filling cracks in concrete based on epoxy resin are used to eliminate small cracks in a monolithic base, and this mixture can also be used to repair the foundation in a private house.
The execution of works to eliminate defects consists of three stages:
- Cleaning the area from small fractions.
- Drying the problem area.
- Filling the crack with epoxy.
Cleaning the problem area is done with a hard metal brush. It is necessary to process the inner part and the surface around the gap. The removal of fine fractions and dust is carried out by blowing, after which you can dry the area with a construction hairdryer.
Before closing cracks in concrete on the street with the use of epoxy compounds, it is necessary to place special nozzles along the entire length of the problem area with a spacing of 30 cm. Installation of nozzles along the height of the wall begins from the bottom of the crack, departing from the level of the blind area 30 cm.
Epoxy adhesive is formed by mixing the resin with the hardener. This mass is injected into the fault through nozzles, starting from the lowest. The solution gains full strength within five days, after which the nozzles are removed (cut), and the surface of the repaired area is wiped using an epoxy solution.
Liquid glass
To eliminate small cracks in the screed, as well as to mask the joints between the floor slabs, it is recommended to use the mixture for filling cracks in concrete with the addition of liquid glass.
Prepare a special solution:
- water glass - in the amount of 20% of the total mass;
- cement - in the amount of 20% of the total mass;
- sand - in the amount of 60% of the total mass.
All ingredients are thoroughly mixed with added water until the desired consistency is formed. The mixture should be quite thick and viscous.
Sealants
Effectively eliminating a crack of almost any size is possible using sealant for cracks in concrete. The elastic material tightly clogs the defect, expanding in volume.
The preparation process also involves cleaning the problem area from large and small fractions, but before using the sealant, it is necessary to moisten the base and cut small grooves for better adhesion of the sealant to concrete.
Self-expanding cords
This method is used to carry out repairs in the bowls of outdoor pools, to restore monolithic foundations and restore the integrity of the outer walls in industrial premises.
For the work, you will need to prepare the site, having cleaned it of small fractions and dust, measure the depth and width of the crack and choose a suitable self-expanding cord or tape that is suitable in size.
In a pre-prepared seam, lay the cord and fill the remaining space with polyurethane sealant from the mounting gun. Excess sealant is leveled with a spatula, and after rising up the material, the surface of the problem area is sanded.
This method of eliminating defects in concrete surfaces allows you to choose a cord to seal any crack, which ensures complete tightness of the seam and a long service life. An important feature of the method is the possibility of performing work at low temperatures.
Concrete additives
For monolithic foundations designed to work in humid environments, as well as for the installation of bowls of outdoor pools, special additives are used in concrete.
The hydrophobic Penetron Admix crystals used in the preparation of concrete in a humid environment form an impenetrable barrier to water, so you can not be afraid of the appearance of small and medium-sized cracks, which can lead to serious violations of the integrity of the entire base.
Jointing Methods
The following methods are used to repair cracks in concrete:
- injection by feeding the solution using special mechanisms into the depth of the crack;
- the use of special solutions based on CPS with additives from polymers, followed by treatment of the repaired surface with polyurethane sealants;
- gunning using special mixtures based on DSP with bituminous additives.
The most effective way to fix the problem is injection. This method involves pre-drilling deep holes that are directed at an angle to the problem area.
With special devices, a solution based on synthetic resins is injected into these holes, which, when building strength, eliminates defects and significantly extends the service life of the structure.
To combat small cracks (up to 4 mm) at personal facilities (cottage, apartment, balcony), repair mixtures based on DSP and epoxy adhesive are used. With proper preparation of the solution, it sets quickly, as a result of which the defect is eliminated.
To strengthen the structure, in which a crack is found that is wider than 4 mm, the use of a solution based on liquid glass is required, for which one part of cement, three parts of water and sand, and one part of concrete are mixed.
Better to use
The type of repair composition depends on the location of the defective surface (vertical or horizontal), the purpose of the room and the operating conditions of the concrete surfaces, as well as the time of year at which the repair is necessary.
Almost any mortar is suitable for repairing horizontal screeds, and only viscous and thick mortars or self-expanding cords are suitable for fixing a problem on a vertical wall. If it is planned to restore the concrete base in rooms with high load (boxes for trucks), compositions with high strength characteristics will be required.
Information on the packaging of the finished repair mixture will help to avoid problems.
Work Implementation Technology
Before closing cracks in concrete, it is necessary to prepare:
- heavy hammer;
- bit;
- a stiff brush with a metal pile;
- putty knife;
- brush;
- one and a half;
- trowel;
- pieces of reinforcement up to 10 cm long.
Work order:
- At the first stage, it is necessary to carefully check the damaged area and eliminate the emerging chips with a chisel and hammer. The cleavage site is trimmed, the crack is roughly processed along the entire length, slightly expanding it.
- Small and large fractions of concrete are removed from the crack using a rough brush, then they are cleaned of dust with a vacuum cleaner. An additional deepening of the seam is made with a spatula to prepare the surface for a firm setting of the repair mortar.
- If the crack width exceeds 4 mm, it is recommended to use local reinforcement, for which, using a grinder, saw transverse overlapping grooves up to 10 cm in length, into which pieces of reinforcement from 4 mm thick are laid. In the same way, through cracks in the base of the floor or ceiling slabs are prepared for repair.
- If reinforcement outcrops are found during the preparation of the problem area, it is necessary to clean the metal parts with sanding paper and then treat it with a solution that protects the metal from rust.
- Before applying the repair composition, the surface is treated with a primer.
- The next step is preparing the repair solution. More often, expanding cement is used to seal cracks made of DSP with an additive of liquid glass. This mixture is applied to the area and moistened. When filling deep cracks, it will be necessary to apply the solution several times, waiting for each previous layer to rise.
- After the repair composition has dried, the joint is grouted, leveling the surface of the problem area.
- Filling of cracks in horizontal surfaces is performed in excess of the level of the repair mortar above the level of the screed, since when rising, the mixture shrinks. Excess mortar is removed with a grinder.
Work on the repaired surface (laying of roofing material on the roof, flooring of the topcoat on the bulk floor, facing the external wall with brick) is carried out no earlier than 72 hours later.