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Postcrete Setting Time

I love using postcrete, it is so much simpler than having to use concrete. But how long does postcrete take to set? Let’s have a look and find out.

how much postcrete to use per post?

So, How long does postcrete take to set?

Postcrete has an accelerant already mixed into the bag. This helps the mixture to set really quick, a lot quicker than a concrete mix would. It depends on the brand used but most postcrete’s will set within 5-10 minutes.

The postcrete I used is blue circle postcrete and this says it has a setting time of 5-10 minutes on the bag. I have always found that it tends to set in around 5 minutes rather than being nearer to 10 minutes.

What can affect the setting time?

There are a few different factors, some outside of your control, that can affect how long postcrete takes to set. One controllable factor is the amount of water you use. If you use a lot of water in your mix then the postcrete will inevitably take longer to set.

This can also be affected by the moisture level in the soil that you have dug your hole into. Wet, damp soils that are holding a lot of moisture will transfer some of this water into your postcrete. This will then increase the amount of time it takes to set.

The humidity in the air can also affect how long your postcrete mix takes to set. The higher the humidity the longer the mix will take to harden. This is true for all concrete materials.

All of the factors above can affect the setting time of postcrete but we are not talking by much, that is unless you have used way too much water. in this case, it may take quite a while longer to set, although it should still set just fine given time.

Fully Cured

Bear in mind that this is just the setting time, that is, the amount of time until the postcrete feels hard. it will have not reached its full strength by this time, far from it in fact.

This is called the fully cured time and can take weeks for the mix to reach. This doesn’t mean it will be weak, it will have a large majority of its strength straight away. it just means that it will take a while longer to reach its peak strength.

How do you use postcrete?

I have a full guide on this here: How to use postcrete but I will also provide a quick breakdown for those of you in a hurry below.

Step 1 – Dig Your Hole

The obvious place to start is by digging your hole for your post.

Step 2 – Fill Your Hole One Third Full With Water

Now add some water to your hole. You want it roughly one-third full and with the water no longer draining away.

In the image, I’m using a bucket to represent the hole.
Fill your hole one third with water
Fill your hole one third with water

Step 3 – Place Your Post In The Hole

Now place your post into the hole, don’t worry about getting it perfectly straight just yet.

Place your post in the hole
Place your post in the hole

Step 4 – Add Postcrete

Now comes the time to add some postcrete, keep adding it until the postcrete comes just above the water level.

Step 5 – Aerate The Mixture

Use a long pole to mix up the postcrete a little. Just jab it up and down into the mix.

Step 6 – Level Your Post

Now comes the time to get your post perfectly straight while the mix is still wet and moveable.

Get your Post Level
Get your Post Level

Step 7 – Keep the Post Straight As The Mix Sets

Now you need to keep the post perfectly straight while the postcrete mix sets. You can do this by either clamping or fixing it to a support structure or just holding it. Fixing it to a support structure is definitely the better way though.The Postcrete Has Just Set

The Postcrete Has Just Set


That’s all there is to it, your post is now set. The postcrete will continue to harden over the next few hours so don’t knock the post as it will still be liable to move a little.

Postcrete vs Concrete, what’s the difference?

again I have a full article on this, find it here: Postcrete vs Concrete

So what exactly is the difference between these two? Well the most obvious, and the one you will notice straight away, is how you use the two. Postcrete is much easier to use than concrete, no mixing is required, just chuck it in your post hole add some water and away you go.

No mixing is required with postcrete

When using postcrete all you have to do is add water to your post hole and then chuck the postcrete in. That’s it, no mixing at all. The postcrete will then proceed to set over 15-20 minutes from my experience.

Contrast this with concrete which you have to pre-mix and mix well before putting it anywhere and you can see that postcrete is much easier to use, when setting posts at least.

For concrete, you also need to order sand and ballast, then mix this in well to make concrete. You will also need a mixer if you are making a lot of concrete. You can use a bucket or even just the floor, but this can be slow or in the case of the floor, messy.
Concrete is stronger than postcrete however. Postcrete only sues very small gravel as ballast whereas in a concrete mix the size and amount of ballast are up to you. Using more ballast in a concrete mix can increase the overall strength of the set concrete.
Concrete made in bulk will also be a lot cheaper than postcrete. This doesn’t include the cost of a mixer or the extra labour involved with making your own concrete. So for just a few small holes postcrete will come out as the cheaper option. But for anything more, such as a full fence with plenty of posts it will be more cost-effective to mix your own concrete.