What is sprayed concrete

1
What is sprayed concrete

• Shotcrete or sprayed concrete
• is concrete conveyed pneumatically through a
  hose and sprayed at high velocity onto a surface.

2
Sprayed Concrete

• Other terms
• Shotcrete containing aggregate gt 6 mm
• Gunite contains aggregate lt 6mm
• Spraycrete
• Gunned concrete

3
Sprayed Concrete

• Uses
• Tunnel linings
• Swimming pools
• Sewers
• Prestressed tanks
• Earth embankment stabilisation

4
Sprayed Concrete

• Process
• Dry spraying
• Wet spraying

5
Sprayed Concrete

• Process
• Dry spraying
• Cement damp (/- 3) aggregate
• Fed through a hose to a nozzle
• Water added through a manifold under pressure
• Sprayed at high velocity onto the surface
• Sometimes accelerators are added

6
Sprayed Concrete

• Dry spray pump

7
Sprayed Concrete

• Dry spray pump

8
Sprayed Concrete

• Process
• Wet spraying
• Cement aggregates and water mixed to slump
• Pumped through hose to a nozzle
• Accelerators added at nozzle
• Air injected at nozzle to increase velocity
• Sprayed at high velocity onto the surface

9
Sprayed Concrete

• Wet spray pump

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Sprayed Concrete

• Factors to consider
• Surface preparation
• Surface must be clean
• Rebound
• Peculiar to spraying waste material
• 10 to 50
• Curing
• Important due to low water content

11
Sprayed Concrete

• Spraying

12
Sprayed Concrete

• Factors to consider
• Surface thickness
• Build up must be controlled or falls off
• Fibre reinforced
• Common practice to improve toughness
• Testing
• In situ by drilling cores and crushing
• Spraying test panels for coring

13
Sprayed Concrete

• Spraying examples

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Sprayed Concrete

• Spraying examples

15
Sprayed Concrete

• Spraying examples