A wet shotcrete machine with an air compressor is a concrete spraying machine used in tunnel support, slope protection, mining, and underground construction. It combines a wet concrete pump and an air compressor system to spray concrete onto rock or surfaces at high speed.
1. How it works
Wet concrete mixing
Concrete (cement, sand, aggregate, water) is mixed before entering the machine.
Pumping
The machine pumps the wet concrete through a hose to the spray nozzle.
Compressed air assistance
The air compressor provides compressed air (usually 0.6–0.8 MPa) that accelerates the concrete at the nozzle and sprays it onto the rock surface.
Accelerator injection
At the nozzle, an accelerator is added to make the concrete set quickly on the tunnel wall.
2. Main components
A wet shotcrete machine with an air compressor usually includes:
Concrete hopper
Hydraulic or piston pump
Spraying hose and nozzle
Accelerator dosing pump
Air compressor (integrated or external)
Control system (manual or remote)
Some machines have a built-in air compressor, making them easier to move and operate on construction sites.
3. Typical technical parameters
Example ranges for wet shotcrete equipment:
| Parameter | Typical value |
|---|---|
| Output capacity | 3–30 m³/h |
| Air pressure | 0.6–0.8 MPa |
| Air consumption | 10–20 m³/min |
| Max aggregate size | 15–20 mm |
| Spraying distance | up to 100–300 m horizontally |
The air compressor ensures the concrete is sprayed with enough velocity for good adhesion and reduced rebound.
4. Advantages of integrated air compressor
No need for a separate compressor on site
Stable air pressure
Easier transportation between working faces
Faster setup in tunnels or mines
5. Typical applications
Tunnel lining and support
Hydropower tunnel construction
Underground mining support
Slope protection
Foundation pits and retaining walls
