Recommended Method for Driving Concrete Posts in the Ground
The prestressed concrete fence post is designed for tough conditions and are driveable with a standard post driver.
Percussion drivers. pneumatic drivers and standard thumpers are all able to be used to drive the concrete fence post.
Australian Concrete Posts recommend that a thick rubber material be used to cushion the direct impact on top of the post when driving them in. Australian Concrete Posts have designed a driving cap to be placed on top of the post. Before cramming in hard ground we recommend a pilot hole.*
Recommended method to hit in a concrete fence post
- Drill a pilot hole about 80 to 100 mm to the depth you require the post to be placed into the ground
- Ensure the pilot hole is vertical.
- In drought conditions wet the post or the ground with about a litre of water. (Old fencers trick to make the concrete post slide into the ground easier).
- Place the driving cap with the appropriate rubber over the post to prevent the metal driver hitting the post.
- Gently tap the post into the ground using small strokes of the driving hammer.
The table below shows the recommended height the driver hammer should be lifted to depending on the hammer head weight.
In some circumstances you are able to hit the posts directly into the ground without using a pilot hole. This will depend on numerous factors like soil condition, how wet the soil is, if there are rocks, your experience at driving the concrete posts into the ground and the way you use your driving hammer. Therefore, we recommend you use a pilot hole which is drilled vertically to the depth you require the concrete posts put into the ground.
What about in rocky country?
If you’re in rocky country, then by using a pilot hole you can judge the depth the post can go into the ground by the depth of the pilot hole drilled.
Remember concrete is not like timber where you just hit the post into the ground and cut the top off and drill the holes.
You have to think backwards and cut the bottom of the post off, to the required length before hitting into the ground. Therefore, measure how deep the pre-drilled hole is and cut the bottom of the post off.
Cutting the post to the desired length is easily done using a concrete cutting blade on a grinder. Click to get some tips on how to on this link.
What about using a percussion driver?
A percussion driver is much more violent on the concrete fence posts. You can usually order one for your machine by your driver machine manufacturer or many contractors have them custom made for their machine by a fabricator. Our ACP Driving Cap is not designed to be used with a percussion driver.
Take the time to get the settings right before you bash the posts and you will save plenty of time in the long run. The percussion driver requires MORE rubber or plenty of high impact polyurethane in the post guide cap to minimise the impact on the post. Usually the rebound pressure should be turned right down on the driver as well. You will perhaps need a few trials to get the right balance and pressure.
MUNRO & El-GRA DRIVERS
Visit your local Munro dealer or website to find information about using a Munro or El-Gra Driver on your prestressed concrete post.
Here's some tips and links to review where you can find the rebound pressure adjustments on an EL-GRA and a MUNRO post driver.
- You will need to adjust, (usually turn down) the Rebound pressure on your percussion drivers to suit driving concrete fence posts.
- Essentially your MUST ensure there is a heavy duty belt rubber or polyurethane layer between the post driver head and the top of the post to minimise the violent impact on the posts.
- Watch this video that demonstrates how to adjust pressures with a Munro Post driver.
- Watch this video that demonstrates how to adjust pressure with an El-Gra Driver
- Click this link to go to Munro Drivers web page
- Click this link to go to El-Gra Drivers web page.
Thousands of posts are driven into the ground across all sorts of ground across Australia. The variations between locations and conditions and machines it will require a bit of patience and trial and error to get it just right for your fence line. There are many contractors who use percussion drivers every day - they are listed on our website - contact any of them for expert advise about how they install concrete posts using their machines!
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