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CEMIX FASTCRETE is a concrete designed exclusively for post hole applications, which require a fast setting time. It is a mixture of sands, aggregates, Portland cement and admixtures. When used in accordance with manufacturer's recommendations, it attains a compressive strength of 20MPa after 28 days.


Used for applications including:

• Fence Posts • Letter Box Posts


• Fast setting

• Easy to use - no mixing required


1. To prevent damage caused by ongoing ground water, apply CEMIX

 BITUPROOF PLUS to the posts (wooden and aluminium), prior to installation.

2. Dig a hole. Allow for 1/3 of the post to be underground.

3. Immediately prior to pouring the bag contents, pre-soak the hole to compensate for any drainage that might soak up the prescribed water. Line the hole with plastic if the soil is particularly sandy or porous.


Do not mix in a wheelbarrow or concrete mixer. See APPLICATION.


1. Pour clean water into the hole containing the post. Bag contents to water ratio: - 20kg: 1.9L to 3L - 25kg: 2.5L to 3.75L

2. Immediately, but slowly and evenly, pour the bag contents into the hole around the post, at a rate of 30 to 45 seconds per bag. Do not empty the bag too quickly as this may lead to dry patches.

3. Prod the dry and wet contents with an up and down movement, using a thin timber or metal rod to ensure adequate water penetration is achieved. If necessary, top up with a small amount of water.

4. Position the post in the centre of hole. After a few minutes it will hold up on its own, allowing you to move to the next post. Do not disturb the post once it is upright.


After 15 minutes the hole can be filled with topsoil. After an hour the post will be able to withstand light work.

Supplier Item#

20 KG - 20981

Download the Data Sheet for full information:

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