Injection

When injected, cracks, joints, voids and pores are filled with injection materials. Superfluid low-viscosity compounds spread in the body of the structure and make concrete , brick or masonry stronger by bonding and sealing even the thinnest cracks.

The injection method has been used recently in construction , but due to the efficiency, speed and low cost of work, it has become widespread.

The injection method is used to reconstruct industrial, cultural, public, public and residential buildings. With the help of injections, the integrity of beams, columns, walls, lintels, floor slabs and other structures is restored. In cases where it is necessary to increase the bearing capacity with the use of external carbon fiber reinforcement systems, cracks are injected first to ensure the normal operation of concrete.

They also resort to technology as a waterproofing measure. Injection compounds can seal any joints and voids to harden concrete or brickwork to prevent moisture and leaks. In this case, injection acts as a cut-off waterproofing, and the injected polymers become membranes , which, when bound to the soil, create an anti-filter curtain. Injection can be used to isolate the input of engineering systems .

The injection method has become widely used due to the fact that it makes it possible:

• perform instant sealing and waterproofing;
• maintain the integrity of the structure without changing the architecture of the building;
• restore hard-to-reach sections of the structure;
• carry out reconstruction without land work;
• carry out work at any time of the year.

An important advantage of injection formulations over rolled materials is their much easier penetration into any cracks and joints.

For injection mixtures, special requirements are put forward:

• reduced viscosity ;
• high penetration;
• high adhesion ;
• resistance to corrosion ;
• minimal shrinkage after hardening;
• long term of operation .

The following types of compositions correspond to these conditions: epoxy and polyurethane resins, microcements and specialized waterproofing solutions.

Resins

Resins are used to inject cracks of not more than 0.5 mm. They fill the microscopic pores, completely restore the bearing capacity and strength of concrete.

Polyurethane Resins

Polyurethane resins are used to fill cracks and create additional waterproofing. Such compositions are used for the treatment of wet joints, the restoration of reinforced concrete monolithic structures. Injection with polyurethane resins allows waterproofing communications and stop pressure and pressureless water inflow.

Epoxy Resins

Epoxy compounds are characterized by high chemical resistance and a quick setting process of the material. Such resins are injected into dry cracks or joints, where they completely restore the bearing capacity of the structure. Upon contact with water, epoxy increases in volume by 2-3 times, creating a layer of waterproofing. The advantage of epoxy resins is the absence of solvents in the composition and good adhesion with different materials.

Microcements (polycements)

Microcements or polycements are used to eliminate more serious damage, cracks with an opening of more than 1 mm. They are Portland cement specially developed for injection, which is distinguished by a particularly high degree of grinding with a fine aggregate fraction, so that the composition easily penetrates into all pores and cavities. Sometimes special additives are introduced into the composition of microcements, which give it additional properties, for example, the ability to control the solidification time.

Polycements are also used to reinforce emergency buildings with reinforced concrete columns - injection piles . Cement compounds are also used to fill shrinkage cracks and stop water inflows.

Waterproofing Compounds

As a composition for waterproofing injection, polyurethane , which is resistant to moisture penetration, is most often used. Seams and joints between monolithic elements are treated with polyurethane, wet areas are restored and holes and cracks in sewer and water networks are isolated.

For waterproofing, low viscosity acrylic gels are used, which increase in volume in a humid environment. The good fluidity of acrylic allows you to quickly create waterproof barriers, fill in cracks and dry the space around them.

All of the above compounds are pumped into a concrete monolith using special tools:

• Injection pumps. They are used for supplying injection compounds to building structures under pressure for repair and waterproofing.
• Packer. A device with a collet, pin-shaped or flat head with a built-in valve for injecting injection formulations into stone, reinforced concrete and other structures. Depending on the working pressure and the compositions used, the packers can be steel, aluminum and plastic. According to the installation method, injection packers are divided into expandable, driven and adhesive.

Injection work is carried out in several stages:

• Preparation of problem areas and grinding cracks.
• Sewing and caulking of cracks and joints with repair compound.
• Drilling injection holes ( holes ) and intersecting cracks.
• Installing packers in drilled holes.
• Injection of the repair compound with constant pressure and flow control.
• Flushing tool.
• Removal of packers after solution polymerization.
• Choking holes with plugging repair compound.

Injection reduces the risk of subsequent shrinkage of the structure and increases the strength characteristics of the foundation and elevated structures.

1. Ministry of Construction of Russia. SP 349.1325800.2017 “Concrete and reinforced concrete structures. Repair and reinforcement rules "
2. GOST 32016-2012 Materials and systems for the protection and repair of concrete structures. General requirements.

• Recommendations for reinforcing reinforced concrete structures of buildings and structures of reconstructed enterprises / Kharkov PromstroyNIIproekt. - Kharkov, 1985
• SNiP 2.03.01 - 84. Concrete and reinforced concrete structures, M., 1985.
• SP 349.1325800.2017 “Concrete and reinforced concrete structures. Repair and reinforcement rules "
• GOST 32016-2012 Materials and systems for the protection and repair of concrete structures. General requirements.