Form · 75–200 mm
Cementitious — indicative fig. M·11
Fire A1 Non-combustibleEmbodied carbon 0.20kgCO₂e/kg LowCompressive 20-48MPa StructuralDesign life 50yr
Pneumatically applied structural concrete achieving 20-48 MPa compressive strength (ACI 506R), enabling formwork-free construction on curved, vertical, and overhead surfaces including tunnels, retaining walls, slopes, and structural repairs at 75-200mm application thickness.
01 Physical
Density 2400-2500kg/m3
Specific gravity 2.40-2.50
Porosity 10-18%
Water absorption 4-8%
Hardness 6-7Mohs
UV resistance excellent
Chemical resistance good
pH tolerance 12-13pH
Surface roughness 500-5000um
02 Mechanical
Tensile strength 1.6-2.5MPa
Compressive strength 20-48MPa
Flexural strength 4.0-7.0MPa
Shear strength 2.0-5.5MPa
Poisson's ratio 0.15-0.20
Impact resistance good
Creep resistance moderate
03 Thermal
Thermal conductivity 1.4-1.8W/mK
Specific heat 840-1000J/kgK
Thermal expansion 10-12x10^-6/degC
04 Compliance & Fire First question
Combustibility class Non-Combustible
Fire resistance level 1-3+hours
Ignition temp Not applicabledegC
Flame spread index 0
Smoke dev. index 0
Heat release rate 0kW/m2
NCC group number 1
05 Sustainability & Health
Embodied carbon 0.197kgCO2e/kg
Carbon footprint 472kgCO2e/m3
Embodied energy 1.08MJ/kg
Water footprint 2200L/m3
Recyclability 25%
Recycled content 10%
Renewable content 0%
End-of-life pathway Demolition to crushed concrete aggregate (CCA) for road base or fill. Landfill for contaminated rebound waste.
Circular score 3/10
VOC emissions 0 (cured)ug/m3
Toxicity rating low
LEED contribution 1-3points
06 Durability · Cost · Logistics
Expected lifespan 50-100+years
Maintenance interval 5-10years
Warranty period 1 (contractor); 50 (design life)years
Material cost (range) 270-380AUD/m3
Material cost (per unit) 270-320AUD/m3
Lead time 1-4weeks
Lifecycle cost 100-250AUD/m2
Annual maintenance 0.50-2.00AUD/m2/year
Market availability Widely available
07 Assessment
Advantages
- Formwork-free application eliminates 30-50% of conventional concrete structural costs
- Compressive strength 32-40 MPa standard, up to 48 MPa — equivalent to AS 3600 N32-N40 structural concrete
- Immediate self-support: accelerated mixes achieve 5-12 MPa within 8 hours for same-shift tunnel advance
- Conforms to any geometry — curved, domed, vaulted, and irregular surfaces at no premium
- Bond to existing concrete and rock: 0.8-2.0 MPa tensile bond for structural repair and rock stabilisation
- Steel fibre reinforcement achieves EFNARC Class E600+ energy absorption — ductile post-crack behaviour
- Non-combustible (AS 1530.1): suitable for all NCC fire resistance applications and all BAL zones
- Rapid deployment: mobile batching and pumping enables remote site access including underground
- Early strength gain enables rock face exposure periods of <4 hours in weak ground
- Australian supply chain maturity: Hanson, Holcim, Boral supply premix across all capital cities
Constraints
- Rebound waste 5-15% (wet-mix walls) to 25-50% (dry-mix overhead) adds 20-40% material cost premium over equivalent poured concrete
- Requires ACI 506.3R-certified nozzlemen — unskilled application produces laminations, voids, and cold joints
- Dry-mix process generates fine silica dust — Safe Work Australia RCS standard 0.05 mg/m3 TWA requires respiratory protection
- Surface quality limited to AS 3610.1 Class U3-U4 as-sprayed — not suitable as architectural-grade finish without treatment
- Accelerating admixtures (>5% dose) reduce 28-day strength by 10-20% and increase permeability
- Thickness uniformity difficult to verify without invasive testing (pin gauges, cores)
- Shrinkage cracking 0.04-0.06% without fibres causes map cracking in exposed panels
- Wet-mix requires concrete pump (40-80 bar), separate air compressor (10+ m3/min) — significant plant cost
- Working time limited to 60-90 minutes for wet-mix batches before pump line blockage risk
- Not suitable for sections thinner than 50mm or where formwork pressure resistance is needed
08 Applications
A1 Tunnel primary lining Primary ground support in NATM/NMT tunnels. Applied 100-200mm immediately behind the face. Sydney Metro City & Southwest used 165,000 m3 of 32 MPa fibre-reinforced shotcrete for 15.5 km of twin bored tunnel.
A2 Rock slope and embankment stabilisation Applied 75-150mm over cut rock faces with pattern rock bolts. Used extensively on Pacific Highway upgrade (NSW), Toowoomba Range (QLD), and Alpine Way (VIC).
A3 Retaining walls Structural retaining walls to 8m height in 75-150mm shotcrete with mesh or fibres. Eliminates formwork on battered or irregular faces. Common in urban rail corridors and road embankments.
A4 Structural concrete repair Applied 25-100mm as repair overlay for spalled, carbonated, or chloride-contaminated concrete in bridges, car parks, and marine structures. Bond 1.5-2.5 MPa to prepared substrate.
A5 Underground mining roadway support Applied 50-100mm for coal and metalliferous mine roadways in NSW Hunter Valley, Queensland Bowen Basin, and WA goldfields. Replaces steel sets and timber lagging.
A6 Swimming pool shells Dry-mix shotcrete (gunite) standard for pool construction — applied 200-250mm over steel reinforcement without formwork. Achieves curved geometries at lower cost than precast alternatives.
A7 Dam face protection and repair Applied to upstream dam faces and spillway aprons for erosion and cavitation repair. 150-200mm on ANCOLD-regulated dams. Used on Hume, Dartmouth, and Serpentine dam rehabilitation.
A8 Architectural feature walls Wet-mix over steel armature and polystyrene formers for sculptural walls and rockwork. Trowelled and bush-hammered finishes. Used in theme parks and resort landscapes.
A9 Fire protection to steel structure Applied 25-50mm as passive fire protection to structural steel, providing 60-120 minute FRL. Used where board systems are impractical.
A10 Emergency ground support Mobile wet-mix plants allow same-day deployment for landslip stabilisation and emergency embankment repair. Queensland Disaster Recovery routinely engages shotcrete contractors after cyclone/flood events.
09 Sources & Standards
Sources pending — citations for this material are not yet recorded. Verify all figures against manufacturer data and current standards before specifying.