mineral / Cementitious / Concrete/Masonry
Concrete Block — Various Finishes (Split Face, Honed, Shotblast)
Architectural CMUs in split face, honed, and shotblast finishes. Standard 390 x 190 mm module in 90–290 mm widths. f'uc ≥ 15 MPa. Non-combustible AS 1530.1 Group 1. FRL 60–240 min structural adequacy per AS 3700 (width and wall-system dependent). Available with oxide pigments from Adbri, Austral Masonry, National Masonry, and Boral.
Atlas code
MIN-CEM-CMU-003
At-a-glance signals
Architectural CMUs in split face, honed, and shotblast finishes. Standard 390 x 190 mm module in 90–290 mm widths. f'uc ≥ 15 MPa. Non-combustible AS 1530.1 Group 1. FRL 60–240 min structural adequacy per AS 3700 (width and wall-system dependent). Available with oxide pigments from Adbri, Austral Masonry, National Masonry, and Boral.
Overview
Executive summary
Architectural concrete masonry units (CMUs) with decorative surface treatments are load-bearing and non-load-bearing masonry products that combine structural performance with designed aesthetic character. Three principal finishes define the range: split face blocks are fractured along a predetermined plane during manufacture, exposing a rough, striated aggregate face that varies naturally in texture and depth; honed blocks are ground smooth after curing, removing the outer cement paste to reveal the aggregate matrix in a flat, low-sheen surface; and shotblast blocks are treated with an abrasive media blast to lightly erode the surface, producing a matte texture with subtle aggregate exposure intermediate between split face and honed. All three finishes are produced to the standard 390 x 190 mm face module in series widths of 90, 140, 190, and 290 mm, enabling consistent coursing with standard hollow CMUs. Compressive strength f'uc is typically 15 MPa minimum per AS/NZS 4455.1. Fire resistance ratings under AS 3700 are wall-system dependent, ranging from FRL 60/60/60 for 90 mm walls to 240/60/60 structural adequacy for 290 mm walls. Manufactured in Australia by Adbri Masonry, Austral Masonry, National Masonry, and Boral Masonry, with oxide pigment additions available across the palette.
Best when…
- Non-combustible Group 1 material — no contribution to fire load.
- Three distinct finishes (split face, honed, shotblast) eliminate need for applied cladding.
- Standard 390 x 190 module integrates with hollow CMU coursing.
- f'uc ≥ 15 MPa structural compressive strength.
- FRL structural adequacy 60–240 min per AS 3700 (system dependent).
- Oxide pigments are UV-stable and factory-integrated.
- Minimum 50-year service life with no applied coating required.
- Suitable for all BAL ratings including BAL-FZ when exposed masonry is used.
- Manufactured nationally by multiple suppliers ensuring availability.
Top advantages
- 01 Non-combustible Group 1 material — no contribution to fire load.
- 02 Three distinct finishes (split face, honed, shotblast) eliminate need for applied cladding.
- 03 Standard 390 x 190 module integrates with hollow CMU coursing.
- 04 f'uc ≥ 15 MPa structural compressive strength.
- 05 FRL structural adequacy 60–240 min per AS 3700 (system dependent).
Top limitations
- 01 Fire resistance values are wall-system and slenderness-ratio dependent; verify FRL with manufacturer for specific configuration.
- 02 Product data is manufacturer-specific and subject to change; always confirm specifications before specifying.
- 03 Heavier than lightweight alternatives (AAC, hollow brick); requires adequate structural support.
- 04 Split face finish is difficult to repair or patch invisibly if damaged.
- 05 Honed finish requires sealing in wet areas to prevent efflorescence and staining.
Technical
Physical ·9
- Density
- 1900-2100 kg/m3 Typical for solid and partially grouted architectural CMUs; hollow units lower.
- Specific gravity
- 1.90-2.10 Derived from density range.
- Porosity
- 20-35 % Standard moulded mix; honed surface has lower surface porosity than split face.
- Water absorption
- 7-12 % Per AS/NZS 4456. Split face higher than honed/shotblast due to exposed aggregate voids.
- Hardness
- 5-6 Mohs Approximate surface hardness of cured concrete matrix.
- UV resistance
- excellent Oxide pigments are iron/chromium/titanium oxide — UV-stable and non-fading. Cement matrix bleaches slightly over decades but pigment colour is retained.
- Chemical resistance
- good (sealed) Good resistance to dilute acids and alkalis when sealed. Susceptible to sulfate attack in high-sulfate soils without appropriate cement blend.
- pH tolerance
- 12-13 (fresh); 9-11 (cured) pH Alkaline material; not suitable for contact with acid solutions without protection.
- Surface roughness
- 0.5-20 (finish dependent) mm Split face: 5-20 mm peak-to-trough. Honed: <0.5 mm. Shotblast: 0.5-2 mm.
Mechanical ·7
- Tensile strength
- 0.3-0.6 MPa Masonry is weak in tension; reinforcement required for tensile loads.
- Compressive strength
- >=15 MPa Austral Masonry Architec Designer Masonry lists f'uc = 15 MPa for split face and smooth/shotblast/honed/polished blocks per AS/NZS 4455.1.
- Flexural strength
- 0.2-0.5 MPa Per AS 3700 characteristic flexural tensile strength parallel/perpendicular to bed joint.
- Shear strength
- 0.2-0.4 MPa Mortar bed joint shear per AS 3700 design provisions.
- Poisson's ratio
- 0.20-0.25 Standard concrete masonry.
- Impact resistance
- moderate Split face surface offers moderate impact resistance; honed surface more susceptible to chipping at corners.
- Creep resistance
- good Low creep under normal masonry compressive loads.
Sustainability & Health
Embodied carbon & energy ·7
- Embodied carbon
- 0.12-0.18 kgCO2e/block Industry-average estimate per 390x190x190 mm CMU. Varies by manufacturer, cement content, and supplementary cementitious material (SCM) use. Fly ash substitution (20–40%) reduces EC by 10–20%.
- Carbon footprint
- 35-55 kgCO2e/m2 (wall face) Estimated for 190 mm single leaf wall, ungrouted, including blocks and mortar. Grouted or reinforced walls higher due to concrete infill.
- Embodied energy
- 0.8-1.4 MJ/kg Estimated range for standard concrete masonry units inclusive of manufacture and transport to site.
- Water footprint
- 0.3-0.8 L/kg Water used in block manufacture for mixing and curing. Closed-loop water recycling is used by major Australian manufacturers.
- Recycled content
- 10-30 (fly ash/GGBFS SCM content typical) % Many Australian CMU manufacturers incorporate fly ash (10–30%) and/or ground granulated blast-furnace slag (GGBFS) as partial Portland cement replacement, reducing embodied carbon and improving long-term strength. Recycled aggregate is not standard but is used by some manufacturers. Check individual manufacturer SDS/EPD for declared recycled content.
- Renewable content
- 0 % No renewable content — mineral product.
- Circular score
- 5/10 /10 Recyclable as crushed aggregate for road base, drainage fill, and low-grade concrete. Cannot be melted and recast into equivalent product. Demolition masonry is commonly crushed and recycled as road base in Australia.
Compliance & Fire
Fire performance ·6
- Combustibility class
- Non-combustible — Group 1 (AS 1530.1) Non-combustible per AS 1530.1. Classified as Group 1 building material per NCC. Suitable for use in all NCC Type A, B, and C construction without cladding exemption restrictions.
- Fire resistance level
- FRL 60/60/60 to 240/60/60 (system and thickness dependent) minutes FRL per AS 3700 is system-specific and depends on wall thickness, grouting, reinforcement, and slenderness ratio. Indicative FRLs (structural adequacy / integrity / insulation): 90 mm wall: 60/60/60; 140 mm wall: 120/60/60; 190 mm wall: 180/60/60; 290 mm wall: 240/60/60. Fully grouted and reinforced walls achieve higher ratings. Confirm with Austral Masonry, Adbri, or National Masonry system data for specific configuration. Compliance demonstrated per AS 1530.4 or via deemed-to-satisfy tabulated data in AS 3700 Appendix.
- Ignition temp
- N/A — does not ignite °C Mineral material — does not ignite.
- Flame spread index
- 0 Non-combustible per AS 1530.1; flame spread index = 0.
- Smoke dev. index
- 0 Non-combustible — zero smoke development.
- Heat release rate
- 0 kW/m2 Non-combustible mineral material. Zero heat release.
Cost & Lifecycle
Capex & lead time ·6
- Material cost (range)
- 40-120 AUD/m2 (wall face) Supply only, ex-yard, 2024–2025 AUD prices. Split face 190 mm: AUD 60–90/m². Honed/shotblast 140 mm: AUD 40–70/m². Large-format split face with oxide: AUD 90–120/m².
- Material cost (per unit)
- 3-12 AUD/block Standard split face 390x190x190: AUD 5–10. Honed/shotblast standard: AUD 4–8. Special sizes or oxide colours: AUD 8–12. Prices ex-yard, 2024–2025.
- Lead time
- 2-6 weeks Standard colours and finishes: 2–4 weeks from order. Custom oxide blends, special sizes, or large architectural orders: 4–6 weeks. Allow additional time for regional delivery.
- Lifecycle cost
- 1-3 AUD/m2/year Low annual maintenance cost; primary expenditure is repointing at 20–30 year intervals (AUD 30–60/m²) and occasional sealer application for honed finish.
- Annual maintenance
- 1-3 AUD/m2/year Very low — primarily inspection. Amortised repointing and resealing costs.
- Market availability
- excellent Nationally available through Adbri Masonry, Austral Masonry, National Masonry, and Boral distribution networks across all states and territories.
Service life & durability ·3
- Expected lifespan
- 50-100+ years Masonry structures commonly achieve 50–100+ years with periodic repointing. Many post-war CMU buildings in Australia remain structurally sound after 60+ years.
- Maintenance interval
- 10-20 years Inspection and repointing of mortar joints. Honed surfaces may require resealing every 5–10 years in harsh environments.
- Warranty period
- 10 years Manufacturer structural warranty typical; check individual manufacturer documentation.
Layer D
Where it's used
External architectural facades
Internal feature walls
Fire-rated wall assemblies
Boundary and retaining walls
Bushfire-resistant construction
Gymnasium and sports halls
Healthcare and institutional corridors
Acoustic separation walls
Residential feature elements
Commercial and industrial construction