Brickwork injection process

Injection is one of the most effective types of repair and restoration work and is widely used to remove and renew brickwork. This technique prevents further destruction of the wall and can significantly extend the life of the structure.

Violation of the external and internal integrity of the brickwork occurs for many reasons. The most common of them are incorrect calculation of the maximum permissible load on the foundation and violation of construction technology. In addition, the masonry begins to collapse with soil heterogeneity, the absence of expansion joints and the close occurrence of the upper aquifers. And also among the reasons note the shrinkage of the foundation, violation of the depth of its foundation and deformation processes in the beams arising from the effects of moisture.

Excessive weight load of the snow cover also affects. A thick layer of snow exerts significant pressure on the supporting structures, resulting in their weakening and destruction. Leaking roof is often the reason for the beginning of the violation of the integrity of the masonry. Water penetrates into the brick walls and has a destructive effect on the material.

The destruction of the masonry occurs gradually, and the tension arising at its first stage is absolutely imperceptible to an outsider's view. Only a professional can feel that something is wrong, who, by the appearance of microcracks, will be able to recognize the beginning of destructive processes. Over time, microcracks grow, interconnect, form a network and attack vertical seams, which, in turn, threatens a serious violation of the integrity of the building. The most negative consequence of such processes is the unhindered passage of cold air inside the walls, which entails their freezing.

With the onset of heat, the brick begins to thaw, as a result of which the wall becomes damp and becomes a favorable environment for the appearance of mold. In addition, the decorative coating also begins to crack and flake off, and plaster and ceramic tiles begin to fall off. At the initial stages of the destruction of masonry, when visible deformation processes are not yet observed, rusty spots may begin to appear on the walls. This indicates ongoing corrosion processes on fittings or embedded parts located inside the wall. To combat the destruction of brick walls, as well as to increase their strength and durability, they use the injection method - sequential injection of various materials into the masonry.

The essence of the method lies in the fact that certain compositions are fed into the brick wall through the holes made - boreholes - under high pressure. The mixtures are pumped through thin pipes equipped with packers (injectors) and is carried out using construction syringes or pumps. The mixtures penetrate into the problem area and fill all voids, pores and cracks. As a result, a reliable barrier is created for the penetration of water inside, and the destruction process stops.

The solidified mass has a moderate reinforcing effect and enhances the insulating properties of the bases of grounded objects. The injection method avoids the re-laying of the main walls and prolongs the life of the structure.In addition to repair work, the method is used for the arrangement of in-wall waterproofing during the construction of subway tunnels, storage facilities with drinking water, underground parking lots, swimming pools and sewers.

To restore brickwork, five mixtures are used, differing in the method of application, operational properties and functional purpose.

Microcement mixtures are widely used for injection and are compositions based on finely ground granular cement clinker. This composition occupies all micro-voids inside the wall, and after hardening forms a substance similar in its performance characteristics to concrete. The advantages of such mixtures are absolute ecological purity, due to the absence of poisonous and toxic impurities in their composition, simplicity of solution preparation and low cost. In addition, microcement mixtures are fully compatible with silicate and polymer resins, which allows them to be used for particularly complex repairs of the lower row of masonry. The disadvantages of the material include a long solidification time of the solution. In some cases, it can reach four hours - the time depends on the outside temperatures and the consistency of the prepared mixture.

Polyurethane resins are represented by moisture-curing compounds, consisting of hydroactive polyurethane, and are capable of effectively eliminating water leaks. This is due to the ability of the material, at the slightest contact with moisture, to instantly foam and form a spongy structure. According to the intensity of foaming, resins are divided into two types. The first is represented by one-component formulations that can increase their original volume by 50 times. Resins of the second type have a two-component design and are used when it is necessary to form an elastic filling with minimal foaming, but high rigidity. Such compositions are somewhat inferior to resins of the first type in terms of the amount of foam obtained, they are able to increase their volume by only 20 times.

The advantages of polyurethane resins are high adhesion to most surfaces, the ability to adjust the intensity and rate of polymerization, resistance to chemicals and absolute harmlessness to human health. In addition, the material does not shrink and is quite resistant to vibration. There are no particular drawbacks in polyurethane resins. The material copes well with the functions assigned to it and has only positive reviews.

Epoxy resins are two-component, low viscosity mixturesconsisting of polyester polyols and modified isocyanate. The material does not contain solvents and cures within 24 hours. The composition is used to seal the external seams of the facade, eliminate cracks, reinforce the masonry and restore the integrity of the walls. The advantages of epoxy resins are high adhesion properties, no shrinkage and high mechanical strength. Among the disadvantages are the high cost of the material and the long time for complete polymerization.

Methyl acrylate gels are capable of increasing their volume during curing and are used to restore brick walls and increase their waterproofing properties. Acrylic injection is able to renew in places, and in the early stages of destruction, even even out the masonry. The advantages of the mixture are good adhesion, resistance to acids and solvents, the ability to work on wet surfaces, good fluidity and low cost of the compositions. The downside is the ability to use the product only at the initial stages of masonry destruction.

Silicate resins are two-component compounds based on water glass. The product is resistant to shear deformation and perfectly resists the effects of alkalis, salts and acids. Silicate injection can be used to partially repair the masonry without having to dismantle it. The advantages of the material include low cost, fast curing and no shrinkage. There are no particular drawbacks in the material, with the exception of the installation process, which consists of two separate stages, in the first of which it is necessary to fill the cracks with liquid glass, and in the second - with calcium chloride.

Repair of brickwork by injection begins with the preparation of the working surface. Grease, plaster, bitumen, paint should be removed from the wall, cleaned of dirt and dust, and, if necessary, sanded. Loose cracks with crumbling edges must be embroidered, and the entire area must be abundantly moistened with water. Wetting is best done with a sprayer or, if not available, with a wet cloth or sponge.

After the water is completely absorbed into the surface, you can start forming holes. They need to be done at an angle of 60 degrees to the wall surface at the rate of two pieces per crack. The diameter of the holes is usually 20 mm, and the depth varies from 5 to 15 cm. When filling the entire masonry with mortar, the distance between adjacent holes should not exceed 15–20 cm. After all holes have been formed, they should also be moistened.

When the composition hardens, you can start filling the cracks using a construction syringe or a hand pump. The choice of tool depends entirely on the volume and complexity of the work. So, to eliminate small cracks using epoxy resins, it makes no sense to purchase a special pump, while repairing serious damage to masonry using cement mortars cannot be done without its help. It is recommended to pump in from the bottom up, moving from the center of the working area to its edges. Then, after the time required for the composition to harden, the fixing devices should be carefully removed from the holes, the grooves should be covered with cement mortar and the finish should be made.

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