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Do I need to mix Rapid Set Postmix before putting it in the post hole?

Quick Answer

No. Our Rapid Set Postmix is a pre-blended material designed to be poured into the prepared post hole and activated with clean water, so separate batching of cement and aggregates is not required.

No. Rapid Set Postmix is supplied as a pre-blended 20kg post-setting material and is designed to be poured into the prepared post hole before being activated with clean water.

That means there is no need to batch separate cement and aggregates or use separate mixing equipment before the product goes into the hole. The supplied instructions are specifically based around this pour-and-activate method.

The sequence matters because the mix begins setting quickly once water is introduced. The supplied product guidance gives an initial set of approximately five to ten minutes. The post should therefore already be positioned, aligned and ready to remain steady before the water activates the mix.

Rapid Set Postmix is intended for setting suitable timber, metal and concrete posts. It is specifically a post-setting product rather than a general-purpose concrete mix.

For quantity planning, the supplied guidance recommends around two bags per post as an initial allowance, although the actual requirement depends on the hole and installation. The post mix calculator can be used for a project estimate.

ECF
Answered by East Coast Fencing on 24th August 2026 East Coast Fencing product knowledge and guidance.