WHAT IS SHOTCRETE?
Shotcrete is a method of concrete work, in which a concrete mix is applied layerwise on a surface to be concrete under the compressed air pressure. The shotcrete is carried out with the shotcrete machine.
(Great Soviet Encyclopedia, vol. 26. M., Sov. Encyclopedia, 1977)
The process of shotcrete has been known for almost a hundred years, and the field and scope of its use are continuously increasing in the world. The process was first applied in 1907 by Carl Akeley in the restoration of the facade of the Field Columbian Museum in Chicago. In Russia, the first shotcrete machine was delivered in 1916 for testing at the Military Engineering Office.
The difference between shotcrete and plastering, which is also often produced by a mechanical method this is a high degree of compaction due to the use of special equipment and the compressed air pressure of at least 4 at and a volume of at least 3 m3/min. Also, it is necessary to distinguish shotcrete (maximum filler diameter up is to 10 mm) and jetcrete or shotcreting (more than 10 mm graded).
Due to good compaction, the layer applied becomes more durable and less porous, eliminating possible loosenesses, pinhole, etc. This allows to significantly improving the mechanical properties of the layer applied, increasing the service life of the layer and the structure as a whole.
In comparison with manual application, gunning will allow to obtain a layer with:
- high density
- high mechanical strength, including immediately after application
- low water absorption, high water resistance and frost resistance
- high level of adhesion to various bases
- high efficiency of work, cost reduction at large volumes
- increased resistance to chemical, fire, and physical effects
Due to its advantages, the gunite (shotcrete), in most cases, is used as a structural (bearing, power) layer.
Necessary conditions for shotcrete:
- Special shotcrete equipment, which in one way or another provides the movement of the shotcrete mix in the spray nozzle.
- A source of compressed air to accelerate the shotcrete mix and give it with the necessary speed for subsequent application to the surface and compaction.
- Source of mixing water (for dry shotcrete)
- Trained specialist-gunman (nozzleman)—the operator of the shotcrete mix application on the surface
- The shotcrete mix of a special recipe that takes into account the requirements for the properties of the shotcrete and the features of the shotcrete equipment operation.
Shotcrete is used when:
- repair works: repairing concrete, reinforcement of reinforced concrete structures, elimination of construction defects, restoration of protective coating
- mining industry: ground reinforcement, for example, shaft walling
- soil stabilization in overland development: construction pits, slopes, hillslopes, coastlines
- construction: in the construction of hydraulic structures and tanks, swimming pools, shells, thin-walled structures (for example, domed structures, structures of 3D panels)
- tunneling: arrangement of lining of tunnel crowns and collectors
- waterproofing and sealing
- processing industry: application of refractory shotcrete mixes and linings in metallurgy, cement, glass, and chemical industries
- creation of objects of artistic purpose: artificial rocks, objects of nonlinear forms
In the subjects of shotcrete and shotcrete, the customers often search: jetcrete, jetcrete materials, shotcreting, shotcrete support, shotcrete mix, gunning materials.