Block · 390 × 190 × 190 mm
Cementitious — indicative fig. M·21
Fire A1 — AS 1530.1 / NCC Group 1 Non-combustibleEmbodied carbon 0.37kgCO₂e/kg LowCompressive 2.25MPa StructuralDesign life 50yr
CSR Hebel Thermoblok AAC masonry blocks (525–650 kg/m³ dry density) deliver one-fifth the weight of normal concrete, intrinsic R-value up to R1.9 per 190 mm leaf, FRL up to 240/240/240, and loadbearing capacity to three storeys. Laid with 2–3 mm thin-bed mortar per AS 3700 and AS/NZS 4455.1. Australia's dominant AAC manufacturer is CSR Hebel (Somersby, NSW), with the product in continuous production since 1990.
01 Physical
Density 525-650kg/m3
Specific gravity 0.53-0.65
Porosity 70-80%
Water absorption 20-35%
Hardness 2-3Mohs
UV resistance Good with coating
Chemical resistance Moderate — protect from sulphates, chlorides and strong acids
pH tolerance 9.0-10.5pH
Surface roughness Wire-cut smooth, Ra ~1.5-3mm
02 Mechanical
Tensile strength 0.25-0.44MPa
Compressive strength 2.25MPa
Flexural strength 0.44MPa
Shear strength 0.3MPa
Poisson's ratio 0.20-0.25
Impact resistance Limited — protect arrises from mechanical damage
Creep resistance Good
03 Thermal
Thermal conductivity 0.10-0.16W/mK
Specific heat 900-1000J/kgK
Thermal expansion 10x10^-6/C
04 Compliance & Fire First question
Combustibility class Non-combustible — AS 1530.1 / NCC Group 1
Fire resistance level Up to 240/240/240 (system-dependent); all BAL categoriesminutes
Ignition temp Does not igniteC
Flame spread index 0
Smoke dev. index 0
Heat release rate 0kW/m2
05 Sustainability & Health
Embodied carbon 0.37kg CO2-eq/kg
Carbon footprint 14-20kg CO2-eq/m2 wall (190mm)
Embodied energy 3.5-5.5MJ/kg
Water footprint 2-5L/kg
Recyclability 80-100 (as aggregate/fill)%
Recycled content <5%
Renewable content 0%
Circular score 5/10
VOC emissions 0g/L
Toxicity rating Non-toxic
LEED contribution MR, EQ, EA categories (LEED v4); Materials + Energy (Green Star)
06 Durability · Cost · Logistics
Expected lifespan 50-100+years
Maintenance interval 5-10 (coating refresh)years
Warranty period 10years
Sound absorption 0.04-0.08NRC
Material cost (range) 80-160AUD/m2 wall face
Material cost (per unit) 6-12AUD/block
Lead time 2-6weeks
Lifecycle cost 180-350AUD/m2
Annual maintenance 1.50-2.50 (external walls)AUD/m2/year
Market availability Good — national distribution, single manufacturer
07 Assessment
Advantages
- One-fifth the weight of normal concrete masonry (~525 kg/m³ vs ~2200 kg/m³), reducing foundation loads, crane picks and manual handling risk.
- Superior intrinsic thermal insulation (k 0.10–0.16 W/mK) — 190 mm wall achieves R1.19–R1.90 without added insulation.
- Non-combustible (AS 1530.1) with FRL up to 240/240/240; satisfies all Bushfire Attack Level (BAL) categories including BAL-FZ.
- Loadbearing to 3 storeys under AS 3700 at 2.25 MPa characteristic compressive strength.
- Thin-bed mortar system (2–3 mm joint) reduces thermal bridging, mortar use and construction time compared to standard masonry.
- Easily worked with standard hand saws and power tools — can be cut, routed and drilled on site without specialist equipment.
- Excellent acoustic separation: 190 mm single leaf Rw ~45–48 dB, suitable for intertenancy walls.
- Termite and vermin resistant — inorganic material with no organic content.
- Low embodied carbon (~0.37 kg CO₂e/kg; ~85–100 kg CO₂e/m² for 190 mm wall) versus normal-weight concrete masonry.
- 50+ year service life with minimal maintenance when correctly rendered and painted.
- CSR Hebel EPD published under Australasian EPD Programme — verified lifecycle data available for Green Star and NCC J5 reporting.
Constraints
- Brittle and easily chipped at arrises — requires careful storage, handling and site protection.
- High water absorption (20–35%) means external faces must be protected with a vapour-permeable, water-resistant render or coating.
- Lower compressive strength (f'm 2.25 MPa) than clay brick or normal concrete masonry; loadbearing use limited to 3 storeys.
- Low abrasion resistance — not suitable as an exposed, uncoated floor or pavement surface.
- Poor impact resistance — vulnerable to hard impacts from tools, forklifts and construction traffic.
- Single Australian manufacturer (CSR Hebel, Somersby NSW) creates supply chain concentration risk.
- Proprietary thin-bed mortar and accessories required; incompatible with standard brick mortar for laid joints.
- Higher embodied energy than fired clay brick on an equivalent m² wall basis at lower thicknesses.
- Alkaline cutting dust (pH 9–11) requires P2 respiratory protection and eye protection when sawing or routing.
- Not suitable as an exposed external finish without protective coating system in Australian climates.
08 Applications
A1 Loadbearing external walls (residential and low-rise commercial to 3 storeys) AS 3700 loadbearing masonry construction using Thermoblok 190 mm blocks. Characteristic compressive strength f'm 2.25 MPa suitable for walls up to 3 storeys. Structural and fire requirements met in a single material.
A2 Non-loadbearing external cladding AAC blockwork as external skin of cavity wall or as non-loadbearing infill panels. Requires vapour-permeable render/coating system on all exposed external faces.
A3 Internal partition walls Lightweight loadbearing or non-loadbearing internal partitions. Reduces floor slab loads. Easily chased for services. Can be directly tiled, plastered or painted.
A4 Fire-rated separation walls (FRL up to 240/240/240) Fire-rated walls for compartmentation, stair enclosures, lift shafts and intertenancy separation. FRL depends on thickness and system detailing — refer CSR Hebel Technical Manual.
A5 Intertenancy acoustic walls — Class 2 apartments 190 mm AAC blockwork wall achieves Rw ~47–50 dB rendered, meeting NCC acoustic separation requirements for apartment buildings when combined with appropriate linings.
A6 Bushfire-resistant construction (all BAL categories including BAL-FZ) Non-combustible AAC blockwork satisfies all Bushfire Attack Level categories under AS 3959. Suitable for external walls in BAL-FZ zones without additional protection.
A7 Thermally efficient residential construction 190 mm Thermoblok wall achieves R1.9 intrinsic thermal resistance, significantly reducing additional insulation requirements. Suitable for NCC Section J compliance in temperate Australian climate zones.
A8 Community and institutional buildings Schools, aged care facilities, community centres. Combines fire safety, acoustic separation, thermal performance and low maintenance in a single robust wall system.
A9 Infill panels in steel or concrete framed buildings Lightweight AAC blockwork infill reduces structural frame loads compared to conventional masonry infill. Requires isolation joints to frame for differential movement.
A10 Acoustic screen and boundary walls AAC masonry for external acoustic barriers alongside roads, rail or industrial uses. Non-combustible, durable and effective acoustic attenuation. Render to protect from weathering.
09 Sources & Standards
Sources pending — citations for this material are not yet recorded. Verify all figures against manufacturer data and current standards before specifying.