Gunned concrete - features of the production of dry and wet

Technology торкретбетона не является новинкой, она используется в строительных работах достаточно давно. Но, в последнее время интерес к ней значительно возрос. В статье расскажем о ее особенностях и применении.

The shotcrete of concrete is a layered application of concrete solutions under high pressure, as a result of which:

• tight interaction of the prepared surface with particles of the composition is provided;
• filling cracks, small pores and voids.

Equipment and technology features

The method provides for dry or wet gunning, it depends primarily on:

• assigned tasks;
• type of equipment;
• possibilities of preparation and delivery of concrete mixwhere GOST is applied to the torque-mix.

Wet way

When using this technology, a ready-mixed concrete solution is supplied to the sprayer (nozzle). It is supplied by special hoses in a continuous flow, thanks to a rarefied air flow or a concrete pump.

Advice: it is not always possible for you to drill concrete goods with your own hands, in this case, special diamond drilling of holes in concrete with the necessary crowns for the diameter will help.

Dry way

In this case, the technology involves the use of a dry mix consisting of cement and fillers. The shotcrete is fed to the nozzle through separate hoses with high pressure water. Materials are mixed directly in the sprayer.

Equipment for gunning concreting consists of:

• specialized complex installations with forced action concrete mixers;
• concrete pump or compressor;
• set of necessary hoses, sleeves and working nozzles.

Technology

Preparation of the solution

1. Depending on the operational requirements for a concrete surface or structure, the composition of a dry shotcrete mixture may have a ratio of cement and sand:

• with mechanical action - 1 to 3;
• atmospheric - 1 to 4.

Tip: observe exactly the time between the preparation of the mixture and its application, as it is limited to 3 hours, otherwise it will begin to clump, and the cement will lose its active properties.

1. When using plasticizing or other specialized additives, they should be diluted in water in the right proportions or added to the dry mixture in a powdered state.
2. The instruction prohibits the use of waste generated during the rebound of the material for the preparation of the solution.

Surface preparation

1. Sand the surface before applying the primary layer of the shotcrete mix using a sandblasting, hydro-abrasive or hydrodynamic method. Make sure that it does not remain:

• concrete delaminations;
• plaster;
• old paint;
• oil and fat stains;
• dust;
• mud.

Also remove rust from the reinforcement.

1. Give a reinforced concrete surface roughness, thereby increasing its adhesion.
2. Divide narrow shells and crevices, leaving no sharp corners on them to reduce rebound.

Tip: for working with concrete products is well suited for cutting reinforced concrete with diamond circles.

1. Install beacons to control the uniform distribution of concrete over the surface.
2. Install once, if reinforcement is necessary, grids with cells from 100 mm. When the size of the latter is smaller, the mesh should be drowned in the first ball of the shotcrete.

1. Blow the prepared surface with compressed air and rinse with a stream of water at a pressure of approximately 0.3 MPa right before the concreting process.

Drawing

Produce torkretirovanie poslojno.

The minimum thickness is 5–7 mm, at the same time the maximum depends on:

• on the type of solution used;
• the location of the surface to be coated;
• метод торгиррения.

Usually this value is 20-50 mm.

Tip: even if the thickness specified by the project is in the range of 20-25 mm, it should be in 2 layers.

Control the height of the layer lead by beacons or probe.

During spraying, move the nozzle along a spiral path, while placing it under 90? to the surface. You can slightly change the angle when filling the armature space or deep sinks.

Apply the layers in horizontal stripes, departing from the surface by about 1 m, covering at once the whole of its area. Do not forget to overlap the docking of adjacent strips by at least 200 mm.

If you apply clean cement mortars that do not contain additives, apply a second layer after 2 hours. In this case, the distance to the surface can be reduced to 800 mm, since a large rebound is no longer expected.

With the introduction of specialized plasticizing and setting accelerating additives into the solution, the interval can be reduced:

• on horizontal surfaces - up to 20 minutes;
• ceiling - up to 40 minutes.

After application, the finished gunning coating should be moistened during the first week (the first time - after 24 hours), if the temperature of the surrounding space is above 5? С.

Tip: during the work must be timely remove the rebound, until he grabbed.

After completion of work or at long breaks, clean the equipment from the remnants of the mixture, rinse and blow with a jet of air until it is completely dry.

Conclusion

The use of gunning concrete technology makes it possible to quickly cover large areas, thanks to the uninterrupted supply of the solution with a concrete pump or compressor over the sleeves. There are two methods of application - wet (can be used in closed rooms) and dry (allows the mixture to be fed over long distances). The video in this article will help you find additional information on this topic.