Resources · A–Z reference
Concrete glossary.
An A-to-Z reference for Sydney concrete terms. AS standards, slab types, finish classes, site-shorthand — the language we use on quotes and drawings.
A
- AS 2870
- Australian Standard for residential slabs and footings. Every Sydney house slab is built to this — covers soil classification, slab type selection, reinforcement, thicknesses.
- AS 3600
- Australian Standard for structural concrete design. Governs suspended slabs, columns, walls and beams in commercial buildings.
- AS 3610
- Australian Standard for formwork. Classifies off-form concrete finishes from Class 1 (architectural smooth) through Class 5 (general structural).
- AS 3727
- Australian Standard for pavements — residential and commercial driveway and footpath construction.
- Aggregate
- The crushed stone or pebbles that make up most of concrete by volume. Exposed aggregate finishes reveal these stones at the surface.
- Air entrainment
- Adding microscopic air bubbles to concrete (4–7% air) for durability against freeze-thaw and improved workability.
B
- Backfill
- Material placed against a structural element after construction — typically against a retaining wall or basement.
- Bleed water
- Water that rises to the surface of fresh concrete as it settles. Excessive bleed compromises finish quality.
- Bondek
- Profiled steel sheet used as permanent formwork for suspended composite slabs. Acts as bottom reinforcement; concrete poured over the top.
- Boom pump
- Truck-mounted concrete pump with articulated boom for placing concrete at distance or height. Essential for tight Sydney sites.
- Burnished concrete
- Finish achieved by repeated power-trowelling at the right cure stage. Sits between plain trowelled and polished.
C
- Cantilever
- Structural element supported at only one end, projecting freely. Cantilevered pool coping is a common Sydney architectural feature.
- Capping beam
- Reinforced concrete beam cast on top of a pile or sheet-pile wall to tie elements and distribute load.
- Class 1 finish
- AS 3610 highest off-form finish — smooth, uniform, no patching, all joints flush. Architectural use.
- Class 2 finish
- AS 3610 standard architectural off-form. Minor surface variation acceptable but no major defects.
- Cold joint
- Joint between two pours where the first pour has already set. Visible in finished concrete unless detailed carefully.
- Control joint
- Saw-cut or formed joint placed at regular intervals to control where shrinkage cracking occurs. Standard practice on every slab.
- Cover
- Distance from the surface of concrete to the nearest reinforcement bar. Critical for durability — too thin and the bars corrode.
- Crack control
- Combination of joint placement, reinforcement design and curing regime aimed at controlling shrinkage cracking.
- Cure / curing
- Process of keeping concrete moist after placement so it gains strength. Most strength gain happens in the first 7 days.
D
- Dowel bar
- Smooth steel bar that crosses a joint, transferring load between slabs while permitting longitudinal movement.
- DLP
- Defects Liability Period — typically 12 or 24 months after practical completion during which the contractor returns to rectify defects.
- Drop slab
- Slab section poured below the main level — often used for showers, planter boxes, garage floors.
E
- Edge beam
- Thickened perimeter of a slab providing additional structural depth around the edge.
- Engineer's details
- Structural drawings issued by the project engineer showing reinforcement, slab thickness and structural detailing.
- Exposed aggregate
- Finish where surface paste is washed off to reveal decorative aggregate. Slip-rated, durable, popular Sydney driveway finish.
F
- Falsework
- Temporary support holding up formwork during pour and initial cure.
- Float / floating
- Initial smoothing of fresh concrete surface using a magnesium or wood float.
- Footing
- Concrete element transferring building loads to the ground. Strip, pad, or raft depending on building type.
- Formwork
- Temporary mould holding concrete in shape until it cures enough to be self-supporting. Stripped after.
- FRP
- Formwork, Reinforcement and Pouring — typically combined as one subcontract package on commercial builds.
G
- Galvanised mesh
- Steel mesh treated with zinc coating for corrosion resistance — used in exposed or marine environments.
H
- Honed concrete
- Finish achieved by diamond-grinding the cured slab to expose a smooth surface. Less reflective than polished, slip-rated for wet areas.
I
- In-situ
- Concrete formed and poured in place (as opposed to precast). Most Sydney slabs are in-situ.
- Integral colour
- Pigment added to concrete at the batching plant so colour goes through the full depth. Permanent, no fade.
J
- JSA
- Job Safety Analysis — task-by-task safety document. Required before commencing work on most commercial sites.
K
- Kerb
- Edge restraint along the boundary of a road or driveway. Standard Sydney profiles: barrier, layback, dish, mountable.
L
- Layback
- Kerb profile that ramps down to road level, allowing vehicle access. Standard for residential driveway crossings.
M
- Mesh (SL)
- Steel reinforcing mesh designated by stock size. SL72 (light), SL82 and SL92 (heavier) are common in Sydney residential.
- MPa
- Megapascals — concrete strength unit. N25 = 25 MPa compressive strength at 28 days.
N
- N-class concrete
- Normal-class concrete designation — N20, N25, N32, N40, N50. Number is the 28-day compressive strength in MPa.
- NATA
- National Association of Testing Authorities. NATA-accredited testing of cube strengths is standard for commercial work.
O
- Off-form finish
- Concrete finish achieved purely from contact with formwork (no patching, plastering or grinding). AS 3610 classes apply.
P
- Pad footing
- Isolated concrete footing supporting a single column or post.
- Pier and beam
- Foundation system using deep piers and connecting beams instead of a continuous slab.
- Polished concrete
- Mechanically polished concrete floor — series of progressively finer diamond grits. Architectural finish.
- Post-tensioned slab
- Suspended slab with steel tendons stressed after concrete cures. Allows longer spans and thinner slabs.
- PPE
- Personal Protective Equipment — boots, hi-vis, hard hat, gloves, glasses. Mandatory on every site.
Q
- QA pack
- Quality Assurance documentation — pour records, slump tests, cube results, curing records, NATA certificates.
R
- Raft slab
- Continuous slab covering the building footprint, with edge and internal beams. Common Sydney residential.
- Rebar
- Reinforcing bar — deformed steel rod for concrete reinforcement. Sold by bar size (e.g. N12, N16, N20).
- Retaining wall
- Wall holding back earth. Cantilever, gravity, counterfort, or block-and-fill types. AS 4678 governs design.
- RFI
- Request for Information — formal query from subcontractor to engineer/architect requiring clarification.
S
- Screed
- Process of leveling fresh concrete to specified height — using a straight edge or laser screed.
- Set-out
- Marking the position of structural elements on site before construction. Critical accuracy task.
- Setting (concrete)
- Transition of fresh concrete from plastic to rigid. Initial set typically 2–4 hours, final set 6–10 hours.
- Site classification
- Soil classification per AS 2870 (Class A through P). Determines slab design.
- Slump test
- Field test measuring concrete consistency. Higher slump = wetter mix = more workable but lower strength.
- SWMS
- Safe Work Method Statement — task-specific safety document. Required for high-risk construction work in NSW.
T
- Tilt panel
- Precast concrete wall panel poured horizontally on site, then tilted up into place. Common for industrial buildings.
- Transfer slab
- Slab transferring load from upper-level columns to a different column grid below. Heavy reinforcement.
- Trowel
- Both noun and verb. Tool for finishing concrete; also the act of finishing.
U
- Upstand
- Concrete element rising above slab level — typical for shower hobs, planter walls, balcony edges.
V
- Vibrator
- Tool for consolidating fresh concrete — releases trapped air, ensures dense pack around reinforcement.
W
- Waffle pod slab
- Slab system using polystyrene pods on a grid, with concrete ribs over and a top slab. Common Sydney suburban.
- Water-cement ratio
- Ratio of water to cement in a mix. Lower w/c ratio = stronger, more durable concrete.
- WHS
- Work Health and Safety — NSW legislation governing safety on construction sites.
Y
- Yield
- Volume of finished concrete from a given batch — usually measured as m³ per m³ of mix design.
Z
- Zero-tolerance
- Specification term meaning no deviation permitted. Rarely truly zero in practice — usually means ±1–2mm.