As a method of adding reinforcement and concrete to existing structures by using high pressure pumping equipment, there are 2 spraying technologies: wet spray and dry spray. We uses dry shotcrete for higher strength, up to C60/75 MPa .
Principles
- Under high pressure, fine particles are retained to create adhesion.
- Larger aggregate particles pop out while compacting the adhered fine particles.
- When the fine grain layer is thick enough, the larger particles will be retained. The cycle repeats itself
- The thickness of each layer of sprayed concrete is about 3-5 cm
- Concrete stress at the connection position: 2 MPa
Advantage
- Effective when dealing with cases of lack of cross-section: punctured floor, excess deflexion, burnt concrete, weathering...
- Ensure solid adhesion, work as uniform components, ensure structural longevity
- Can be used even when the reinforcement is in a plastic state
- Low shrinkage of shotcrete reduces the risk of cracking in concrete
Disadvantage
- Increase the size of the structure, reduce the clearance
- Complex quality control
- The cost is high
