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Temporary Lining:
Steel Fiber Reinforced Shotcrete
Steel fiber reinforced shotcrete is a composite of cement, aggregates, water, steel fibers and plasticizers, which is sprayed through a compressed air nozzle on the surface.
Shotcrete is applied:
- Without formwork
- For consequent layers
There are two common methods to produce shotcrete:
- Dry mix method, water added during projection
- Wet mix method, water added to concrete mix before projection
Both methods are compatible with fiber reinforced concrete technology.
The main advantages of steel fiber reinforced shotcrete are:
- Improves toughness, flexural resistance, increase tensile strength and shear resistance
- Reduces shrinkage cracking
- Improves safety: it doesn't require man labor for the welded mesh reinforcement and reduces the risk of unexpected collapse or failure of the vault
- Optimizes sprayed lining thickness
- Reduces rebound
- Reduces tunnel lining construction time
Final Lining:
Cast or Pumped in Situ Steel Fiber Reinforced Concrete
Steel fiber reinforced concrete can be used in the tunnel final lining. Steel fiber reinforced concrete is cast or pumped directly inside the formworks. It can be used in final lining in these situations:
- When the lining has requirements of tensile and flexural stresses in the concrete
- To avoid or optimize the traditional steel bars reinforcement
The main advantages are:
- Reduces tunnel lining construction time, avoiding man labor for the steel bars reinforcement
- Optimizes sprayed lining thickness
- Reduces shrinkage cracking
- Reduces permeability
- Improves safety
- Improves toughness, flexural and shear stress
A blend of WIRAND® steel fibers and FIBROMAC® synthetic fibers can also be used in tunnel linings. The synthetic fibers are added as fire protection for the concrete lining.
Maccaferri offers free design assistance. Contact our Technical Department at tunnel lining design support.
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