How Long For Postcrete to Set?
Postcrete, a pre-blended cement used to set fence posts in the ground, dries extremely fast, within about ten minutes when mixed with water however, this very much depends on the conditions so do read the instructions on the pack. Fast drying times are hugely competitive compared to one to two days for standard concrete and means that you can move from one fence post to the next very quickly.
The mixture is suitable for fixing fence posts made of wood, concrete or metal, and will begin to set in just one or two minutes, becoming fully dry within five to ten minutes.
What Factors Will Impact How Quickly Postcrete Sets?
The primary reason your Postcrete might not be set properly is that you have added too much water to the mixture. Postcrete comes in sealed, waterproof bags, normally 20 kg or 25 kg.
It's important to follow the dilution instructions carefully because weak Postcrete will:
- Take longer to set.
- Have reduced strength.
- Last a shorter period.
- Potentially crack through shrinkage.
Overly damp Postcrete is vulnerable to damage since the moisture content dries, and often means the concrete mixture will show large cracks. The compressive strength of dried Postcrete mixed with excess water is massively reduced.
Temperatures can also have an impact, and it's not advisable to use Postcrete in conditions colder than 3 °C.
However, it is a fine balance because it is equally essential to keep Postcrete damp during application. The hardening process will slow or stop altogether if the solution is too dry or the atmosphere absorbs too much water.
How Are Postcrete and Concrete Different?
Traditional concrete usually takes 24 to 48 hours to set and up to a week to cure, reaching optimal strength after around four weeks.
The benefit of Postcrete is that it is a pre-blended mixture of concrete ingredients, which you simply add water to and use without any further handling.
Postcrete has pros and cons in that it is ideal for fixing fence posts and other small jobs such as filling potholes.
If you need to lay concrete, screed flooring, or render brickwork, most professionals will recommend concrete since it offers a higher level of the compressive strength we mentioned earlier.
The very fast drying times also mean that you need to move quickly when working with Postcrete, keeping the mixture damp but never allowing it to dry out or become too wet.
Concrete needs to be levelled, so Postcrete isn't appropriate for some jobs since it allows little time to be levelled off to an exact degree.
Installing a Fence Post With Postcrete
Postcrete is very easy to use, and you can usually calculate the number of bags of Postcrete required accurately, depending on how many fence posts you need to fix and the depth of the post holes.
Most Postcrete products come in 20 kg or 25 kg bags, with an average of one to 1.5 bags required per fence post.
To apply Postcrete:
- First, dig your fence post holes, and insert the post to the correct depth for the fence height.
- Fill the hole with around one-third water, and empty a standard 20 kg bag on top.
- Mix the content slightly to ensure the Postcrete is wet throughout.
- Add any remaining required bags evenly around the edges of the fence post hole, ensuring you have sufficient water to wet all Postcrete used.
- Cover the Postcrete with soil to provide a neat, tidy finish.
This straightforward process makes Postcrete convenient for fencing projects since there is little risk of getting the mixture wrong, provided you double-check the instructions on the product packaging.
Postcrete is suitable for fixing concrete, wood or metal posts.
Frequently Asked Questions - How Long for Postcrete to Set?
Let's work through some of the commonly asked questions about working with Postcrete and ensuring it has dried to an optimal consistency!
How Many Bags of Postcrete Will I Need Per Fence Post?
You should always dig fence posts down to at least 30% to 50% of the eventual height of the fence panels above ground.
The deeper the fence posts, the more stable the foundations of the fencing, and the more durable the finished result.
To calculate how many bags of Postcrete you need, you'll need to look at:
- The number and size of the fence posts and the required depth to dig down to.
- How wide each hole will be, and then the remaining volume when deducting the fence post size from the total cubic area.
- The size of the Postcrete bags you are buying.
As a rough guide, most fencing projects require at least one Postcrete bag per post, but possibly two.
One pack will normally fill a hole of 8 x 30 inches, with a standard 4 x 4-inch fence post.
What Can I Use Postcrete For?
As the name suggests, Postcrete is designed to fix fence post panels, but you can use it for various non-structural or weight-bearing projects, such as:
- Installing outdoor washing lines.
- Fixing gate posts for gates up to a metre wide.
- Filling small potholes on domestic driveways.
How Quickly Does Postcrete Dry?
Postcrete dries in a very short timeframe and under 15 minutes provided the weather conditions and water concentration are suitable.
You should still leave it for around two hours before applying any load to ensure the mixture has set through.
Applying Postcrete immediately is essential, especially if you have mixed it with water before applying, since it may be set before you have used it.
How Long Does Postcrete Last?
Properly installed fencing should generally last for around 20 years and up to 40 years, so getting the Postcrete application right is important.
Much depends on the type of posts you're using since the posts are more likely to begin to wear down or deteriorate than the Postcrete.
A pressure treated fence post will last around ten years in the soil.
Wooden fence posts tend to come treated with waterproofing solutions, but the wood remains a degradable material susceptible to rot, damp and insect infestations.
Concrete foundations will last for decades, so they are usually much stronger and more durable than any alternative.
References:
- https://cementanswers.com/can-i-use-Postcrete-as-concrete/
- https://askinglot.com/how-long-does-it-take-Postcrete-to-set
- https://www.jacksons-fencing.co.uk/the-edit/the-benefits-of-using-Postcrete
- https://www.withamtimber.co.uk/blog/Postcrete-vs-concrete
By Johnny Fuller
Home Improvement editor at NWrenovations.com
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