Shotcrete fiber
Fewer metres of mesh, more metres of tunnel per shift
In sprayed support the binding constraint is rarely material cost — it is cycle time. Less mesh handling, faster support cycles and a smaller crew turn straight into advance rate.
The expensive problem
Fixing mesh is the slowest part of the cycle
It is also the part that keeps people under freshly exposed ground for longest.
- Mesh sheets cut and bent to a profile that is never quite regular
- Crews working at height under partially supported ground
- Rebound trapped behind the mesh, wasting sprayed material
- Shadowing behind the bars, leaving voids in the lining
- Every fixing hour is an hour the face is not advancing
- Plant and crew standing while the support cycle catches up
The Polyguard solution
ShotGuard PG SC-48, dosed in the sprayed mix
ShotGuard is shaped and sized to pump and spray cleanly, with low rebound and no blocking at the nozzle. The reinforcement arrives with the concrete, follows the excavated profile exactly, and takes the fixing operation off the critical path.
- Grade
- PG SC-48
- Fiber length
- 48 mm
- Typical dosage
- 4–9 kg/m³
- Application
- Wet and dry spray
What comes off the cycle
Operations that leave the critical path
- Mesh cutting, lifting, positioning and fixing
- Working platforms and access set up purely for fixing
- Rebound losses caused by spraying through a mesh curtain
- Void and shadowing rework behind bars
- Crew and equipment standing time between spray passes
- Exposure time under freshly excavated ground
Cost per linear metre
The right unit is metres of tunnel
Price per kilogram of fiber tells you nothing about a tunnel. Divide the whole support package — steel, fixing labour, crew and plant time — by the metres it delivers, and the comparison becomes decidable.
Steel purchaseTransport & storageCutting & lap wasteChairs & spacersPlacing labourSupervisionPlacement delayPolyguard fiber, dosed in the mix
Proportions are illustrative. Fixing rates vary widely with ground class and profile.
Two horizons
Programme now, durability later
During the drive
- Support cycle shortened — more advance per shift
- Smaller crew at the face, less time under exposed ground
- Lower rebound, so less sprayed material wasted
- No mesh delivery, storage or cutting logistics
In service
- No corroding steel in a wet, chloride-bearing lining
- Reinforcement that follows the profile with no shadow voids
- Fewer local repairs to a lining that is hard to access
- Micro fiber can be added where fire spalling is a design case
Worked example — 1,200 m drive, 18 m sprayed perimeter
Illustrative rates. Replace every figure with your own in the calculator below.
- Sprayed area
- 1,200 m × 18 m = 21,600 m²
- Lining
- 120 mm → 2,592 m³
- Mesh at 3.0 kg/m², 0.95 /kg
- ≈ 61,560
- Fixing at 2.40 /m²
- 51,840
- Fixing time at 4 min/m²
- 1,440 crew-hours
- Crew & plant at 85 /hour
- 122,400
- ShotGuard at 6 kg/m³, 3.60 /kg
- ≈ 55,987
- Saving per linear metre
- ≈ 149.8 /m
The fixing hours are the headline. Removing 1,440 crew-hours from the critical path is worth more on most drives than the steel it replaces.
Your numbers
Shotcrete & tunnel calculator
Set your own ground-class fixing rate and crew cost. The output is expressed per linear metre so it can go straight into a tender comparison.
Shotcrete & tunnel calculator
Cost and cycle time per linear metre of tunnel.
CurrencyUSD
Result
- Sprayed area
- —
- Shotcrete volume
- —
- Steel avoided
- —
- Mesh, installed
- —
- Mesh-fixing hours removed
- —
- Crew & equipment time
- —
- Polyguard, dosed
- —
- Saving per linear metre
- —
- Total project saving
- —
Indicative only. Fixing rates and crew costs vary with ground class, profile and method. Confirm the dosage by design and a site trial.
Questions engineers ask
Spray, dosage and acceptance
Wet or dry process?
How is performance demonstrated?
What happens to rebound?
Can it be combined with lattice girders?
Price the whole shotcrete cycle, not just the mesh
Send the drawing, the exposure class and the loading. You get a dosage recommendation, a data sheet and an installed-cost comparison against your current specification.