Atlas index
Sheet · Sizes pending
Cementitious — indicative fig. M·05

Standard reinforced concrete floor and roof slab, 100–250 mm thick, 20–50 MPa characteristic strength — the single most widely used structural element in Australian construction, compliant with AS 3600 and NCC Volume One.

01 Physical

Density 2400kg/m3
Specific gravity 2.4
Porosity 8-14%
Water absorption 3-6%
Hardness 5-7Mohs
UV resistance excellent
Chemical resistance good
pH tolerance 12.5-13.5pH
Surface roughness 5-200μm

02 Mechanical

Tensile strength 2.2-4.2MPa
Compressive strength 20-50MPa
Flexural strength 2.7-5.1MPa
Shear strength 0.8-3.5MPa
Poisson's ratio 0.2
Impact resistance moderate
Creep resistance moderate

03 Thermal

Thermal conductivity 1.5-2.0W/m·K
Specific heat 840J/kg·K
Thermal expansion 10-12×10⁻⁶/°C

04 Compliance & Fire First question

Combustibility class Non-combustible — AS 1530.1 Group 1
Fire resistance level 60/60/60 to 240/240/240 depending on thickness and support conditionsminutes
Ignition temp N/A°C
Flame spread index 0
Smoke dev. index 0
Heat release rate 0kW/m²

05 Sustainability & Health

Embodied carbon 0.10-0.18kgCO₂e/kg
Carbon footprint 36-80kgCO₂e/m²
Embodied energy 0.8-1.5MJ/kg
Water footprint 150-300L/kg
Recyclability 100%
Recycled content 0-50%
Renewable content 0%
Circular score 6/10
VOC emissions 0μg/m³
Toxicity rating Low (hardened); Moderate hazard (wet/fresh)
LEED contribution 1-3points

06 Durability · Cost · Logistics

Expected lifespan 50-100+years
Maintenance interval 5-10years
Warranty period 1-2years
Material cost (range) 200-350AUD/m³
Material cost (per unit) 36-70AUD/m²
Lead time 1-7days
Lifecycle cost 50-120AUD/m²
Annual maintenance 0.5-2AUD/m²/year
Market availability excellent

07 Assessment

Advantages

  • Exceptional compressive strength: 20–50 MPa providing load-carrying capacity for any building type
  • Excellent fire resistance: non-combustible, FRL up to -/240/240 achievable per AS 3600 Table 5.3.2 at 200 mm
  • High thermal mass: 2,400 kg/m³ × 840 J/kg·K reduces diurnal temperature swing by 8–12°C in Australian climates
  • Long service life: 50–100+ years per AS 3600 design life with appropriate exposure class selection
  • Unlimited span adaptability: one-way, two-way, flat plate, post-tensioned and banded configurations to 15 m span
  • Readily available: all capital cities and most regional centres have multiple ready-mix suppliers within 45 min haul
  • Universal compatibility: all finishes applicable — tiles, carpet, polished concrete, coatings, raised floor, screed
  • 100% recyclable: crushed concrete aggregate (CCA) suitable for sub-base, drainage layers and new concrete (≤30% replacement)
  • Reduced storey heights vs. beam-and-slab: flat plate construction saves 200–400 mm per floor in high-rise
  • Cost certainty: competitive tendering environment and standardised mix designs give reliable AUD 200–350/m³ supply pricing

Constraints

  • High embodied carbon: 0.10–0.18 kgCO₂e/kg, or ~240–430 kgCO₂e/m³ for a 200 mm slab
  • Long curing cycle: 28 days to design strength; soffit formwork cannot strip before ~14–21 days
  • Heavy self-weight (2,400 kg/m³) increases foundation and column loads significantly
  • Shrinkage cracking: drying shrinkage 400–800 microstrain requires control joints every 4–6 m
  • Skilled formwork and concrete placement crews required; defects difficult to remediate once set
  • Poor thermal insulation: R-value ~0.10 m²·K/W per 150 mm; additional insulation always required
  • Wet trades on critical path: weather delays, hot weather concreting protocols add programme risk
  • Moderate acoustic performance without topping or floating floor: STC ~50–54 for 150–200 mm slab
  • Demolition generates large volumes of hard waste; crushing required for recycling as aggregate
  • Susceptible to chloride-induced reinforcement corrosion in coastal/industrial exposure classes without adequate cover and concrete grade

08 Applications

A1 Suspended residential and apartment floors 150–200 mm N32–N40 flat plate or flat slab with band beams; the dominant floor system for medium and high-density housing in Australian cities, valued for speed of construction and flat soffit appearance.
A2 Commercial office and retail floors 200–250 mm post-tensioned flat slab providing spans of 8–12 m in open-plan offices; typically N40–N50 in high-rise construction for combined structural efficiency and fire resistance.
A3 Multi-storey carpark decks 200 mm N40 PT slab with 65 mm cover (B2 exposure class) for open carparks; requires waterproof membrane or crack-control detailing at exposed upper decks to prevent chloride ingress.
A4 Ground-supported slab-on-ground 100–150 mm N25–N32 slab on compacted fill with D500L mesh; used in housing, warehouses, and retail; design per AS 2870 for residential and AS 3600 for commercial applications.
A5 Industrial warehouse and logistics floor 150–200 mm N32 slab designed for forklift and racking loads; power-trowelled surface with joint layout to AS 3600 and proprietary joint filler; often uses higher-strength concrete for abrasion resistance.
A6 Transfer slabs and podium structures 300–600 mm N50 post-tensioned transfer slabs redistributing column loads at podium level in mixed-use towers; engineering-intensive design requiring detailed deflection and creep analysis.
A7 Roof slabs and green roof bases 150–200 mm slab with waterproof membrane for flat or low-pitched roofs; thermally exposed position requires expansion joint planning at 15–20 m centres; suitable base for planted green roofs.
A8 Basement floors and raft foundations 300–500 mm raft slab in C2 exposure class concrete (N40–N50, 65 mm cover) for basement construction; post-tensioned rafts minimise cracking and enable long spans between core walls.
A9 Bushfire-resistant construction Concrete slab on ground and roof slab meet all BAL ratings including BAL-FZ under AS 3959; combined with concrete masonry or steel-clad walls provides fully non-combustible building envelope.
A10 Educational, health, and public buildings 200 mm N40 slab standard in NCC Class 9 buildings; combined fire resistance, acoustic performance (Rw ≥ 50 with floating floor), thermal mass, and 100-year design life make concrete slabs the default structural system for public infrastructure.

09 Sources & Standards

Related materials

M·12 Shotcrete/Sprayed Concrete MineralM·17 Concrete masonry unit MineralM·06 Exposed aggregate concrete MineralM·07 Polished concrete floor MineralM·32 Precast concrete column Mineral
MATERIALS ATLAS · CL·AD M·05 · data indicative — verify per project