What is Shotcreting?

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What is Shotcreting?

Shotcreting is a method of concrete work that involves applying concrete mixture in layers onto a surface with compressed air pressure. Shotcreting is performed using a shotcrete machine.

Shotcreting is commonly understood as the mechanized application of concrete and compositions with a non-cement compound (such as fire-resistant coatings, or linings) in a formwork-free method. The term ”shotcrete” can be used to simplistically refer to a shotcrete layer.

Shotcreting has been known for almost a century, and its applications have been growing steadily around the world. The process was first used in 1907 by Carl Akeley during the restoration of the façade of the Field Columbian Museum in Chicago.

The difference between the shotcreting and plastering, which is also often performed in a mechanized way, is in a high degree of compaction as a result of using special equipment and compressed air pressure of at least 4 atm and a volume of at least 3 m3/min. There is also a distinction between shotcrete (maximum aggregate diameter up to 10 mm) and spray-on concrete or sprayed concrete (a fraction over 10 mm).

Good compaction makes the applied layer more durable and less porous, eliminating possible leaks, voids, and so forth. This significantly improves the mechanical properties of the applied layer, increasing the durability of the layer and the structure as a whole.

Compared with manual application of concrete, shotcreting allows you to get a layer with:

  • high density
  • high mechanical strength, even immediately after application
  • low water absorption, high water and frost resistance
  • high level of adhesion to various substrates
  • durability
  • increased resistance to chemical, fire, and physical factors

Requirements for shotcreting:

  • Special shotcrete equipment, which in one way or another enables the movement of the shotcrete mixture in the spraying nozzle.
  • Source of compressed air to accelerate the shotcrete mixture and give it the necessary speed for its subsequent application on the surface and compaction.
  • Source of mixing water (for dry mix shotcrete process).
  • Trained shotcrete operator to apply shotcrete mix on the surface
  • Special formula shotcrete mixture that is made taking into account the requirements of shotcrete properties and the specifics of the shotcrete equipment.

Shotcreting is used:

  • for repair and renovation: for example, concrete repair, strengthening of reinforced concrete structures, elimination of construction defects, restoration of protective coating;
  • in mining: for rock consolidation works, such as the consolidation of mine vaults;
  • for strengthening of soil in surface construction: construction pits, slopes, declivities, coastlines;
  • in construction: in the construction of hydraulic structures and tanks, swimming pools, shells, thin-walled structures (such as domed structures, structures made of 3D panels);
  • in tunnel construction: tunnel and collector vault lining;
  • in waterproofing and sealing;
  • in processing industry: application of fire-resistant and lining compositions in metallurgical, cement, glass, and chemical industries;
  • in construction of artistic objects: artificial rocks, non-linear buildings;
  • In the context of shotcreting users often search for “shotcrete”, “gunite”, “sprayed concrete”, “nozzled concrete”