Made by Cement Australia
Concrete · High strength
PROSTRENGTH Extra Strength Concrete 20kg
A high strength concrete mix designed for up to 50MPa in lab tests, twice a standard mix. Walk on it after 24 hours.
Comes on pallets of 48 or 84 × 20kg bags.
1 bag (less than a pallet).
Lead time: Approx. 1 to 2 working days
Code: 200842045
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 PROSTRENGTH Extra Strength Concrete 20kg
A rich blend of cement, aggregate and sand for jobs with hard access or a need for more strength. It is designed to deliver up to 50MPa, twice the strength of a standard concrete mix, and gains strength faster, so you can drill it sooner or walk on it the next day.
The 50MPa figure was reached under controlled lab conditions at 23°C, so results on site can vary.
- Strength
- Up to 50MPa (lab, 23°C)
- Water
- 2.0L per bag
- Formwork off
- After 24 hours
- Foot traffic
- After 24 hours
- Yield
- About 110 × 20kg bags per m3
- Temperature
- 5°C to 35°C
- Approved
- TMR MRTS14, frangible support posts
Best for
- Small slabs, paths and footings
- Gate, flag and automatic gate posts
- Bollards, clothes lines and swings
- Uprights for pergolas, playgrounds and decks
- Concrete repairs and landscaping
Not for
- Placing in temperatures under 5°C or over 35°C
- Aluminium posts, unless their maker confirms it suits them
How to use
- Measure 2.0L of clean water per bag. With a mixer the water goes in first and the bag after; with a barrow, tip the bag in, make a hollow and pour the water in.
- Mix thoroughly. If it needs more workability, up to 0.5L extra per bag is the limit. Too much water ruins good concrete.
- Fill the formwork right into the corners and compact. Screed it level, then finish the top with a float or trowel.
- Formwork can come off and foot traffic can start after 24 hours. Keep the surface damp for 7 days to reach full strength.
- For a pergola or deck upright set in a stirrup, the post can be attached after 5 hours.
Storage & safety
Keeps about 6 months from manufacture, sealed, dry and off the ground. Do not use a bag that has gone hard. Wear dust-proof goggles and PVC or rubber gloves. Each 20kg bag is a two-person lift. Storing and handling bagged cement.
How many bags?
About 2 × 20kg bags fill a 200 × 600mm post hole around a 90x90 post, by our estimate (100mm gravel base, 10% extra).
Not sure this is the right concrete? Compare the four bagged concretes.
Documents
The manufacturer's own sheets. Open one to read it on the page, share it or download the PDF.
PROSTRENGTH Extra Strength Concrete questions
Cement Australia designs it to deliver up to 50MPa, twice a standard concrete mix. That figure comes from lab tests at 23°C, so take it as a guide.
The next day. Foot traffic can start after at least 24 hours, the same time the formwork can come off.
Start with 2.0L per 20kg bag. Up to another 0.5L is fine if you need it more workable.
Yes. Mix it in a barrow, fill the hole to just below the ground and tamp out the air pockets. The supports can come off in half the time of standard Concrete Mix, which needs at least 24 hours.
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.
Concrete Mix 20kg
General purpose concrete for small jobs: posts, small footings, pads and garden edges.
PROSTRENGTH Rapid Set Concrete 20kg
High strength rapid set concrete for gates, professional fencing and signs. Supports off after 30 minutes.
Also for this job: Post supports (stirrups)