Made by Cement Australia
Cement · General purpose
General Purpose Cement 20kg
Straight Type GP cement to AS3972 for mixing your own concrete, mortar, render and grout.
Comes on pallets of 48 or 84 × 20kg bags.
1 bag (less than a pallet).
Lead time: Approx. 1 to 2 working days
Code: 200841930
Available to order from Allmat. Click and collect or delivered across Adelaide.
How many bags do I need?
Work it out with the free Allmat concrete calculator.
About General Purpose Cement 20kg
Straight cement, made to the Type GP requirements of AS3972. Mix it with sand and aggregate for concrete, or with sand for mortar and render. Cement Australia makes it for almost any building job, from slabs and driveways to pavers and blocks. Batching your own suits jobs of about 0.1 to 0.5m3; a bigger pour is usually ready-mixed concrete by truck.
- Type
- GP to AS3972
- Made from
- Portland cement clinker, gypsum and limestone
- Admixtures
- Compatible with most
- Render coverage
- About 10m² per 20kg bag plus sand, at 5mm
- Paint render
- Water-based after 14 days, oil-based after 28
- Curing
- Keep moist for 7 days
Best for
- Batching your own concrete for small slabs, paths and footings
- Cement render on brick, block and fibre cement sheet
- Mortars and grouts
- Pavers, blocks and panels
- Structural concrete
Not for
- Jobs that call for rapid setting or high early strength: Cement Australia suggests a more specialised cement
How to use
- Batch the cement, sand and clean aggregate by volume into a non-porous barrow or tub, using a bucket so the measures stay even. Use a mixer for a big job.
- Add clean water gradually while mixing until it is just workable. Excess water ruins good concrete.
- Place it as soon as it is mixed, and keep it damp for 7 days.
Mix ratios
Concrete and render ratios, with the bags of cement per m3, are in our concrete mix ratio table. Mortar mixes are on the mortar calculator.
Storage & safety
- Cement Australia gives grey cement products and lime a shelf life of about 6 months from manufacture, kept unopened, off the ground and away from moisture. Off White Cement keeps about 3 months.
- Open a bag only when you need it, and use the contents that day.
- Bagged cement that has hardened or gone lumpy has reacted with moisture and should not be used.
- Cement dust and wet mixes cause serious eye damage and skin irritation. Wear dust-proof goggles and PVC or rubber gloves, and avoid breathing the dust.
- Cement Australia rates a 20kg bag of any cement-based product as a two-person lift. Use a barrow or trolley to move several.
Documents
The manufacturer's own sheets. Open one to read it on the page, share it or download the PDF.
General Purpose Cement questions
GP is straight cement, made from Portland cement clinker, gypsum and limestone. Builders Cement (Type GB) blends GP cement with fly ash or slag for better workability, later-age strength and a lower carbon footprint, but early strength gain can be slower, so curing matters more.
Almost any concrete job: slabs, driveways and footpaths, structural concrete, pavers, blocks and pipes, plus renders, mortars and grouts.
Mix 1 part GP cement with 3 parts builders' sand and water, and use it within 30 minutes of mixing. Apply 2 to 10mm per coat, inside or out. If another coat follows, scratch the surface within 30 minutes and wait at least 3 days before the next coat. A 20kg bag plus its sand covers about 10m² at 5mm.
Water-based paint can go on after 14 days. Oil-based paint needs at least 28 days.
Yes. GP cement is compatible with most admixtures and supplementary cementitious materials.
Sources and guidance
The product information on this page comes from Cement Australia's published product data sheets, safety data sheets and website (see Documents above). It is general guidance only. Other manufacturers may give different advice for their own products, so always follow the instructions on the bag and the product's data sheet. Structural work, such as footings for buildings, must follow your engineer's design and the relevant Australian Standards.
You may also need
Often ordered with this product. Use + Add to pick the option and quantity and put it on the same quote.
Builders Cement 20kg
Blended Type GB cement for a creamy, easy to work mix with a smooth finish.
Low Carbon Cement 20kg
A direct replacement for GP cement with 30% less embodied CO2, using the same mix ratios.