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Very often in gardening or landscaping there is a need to dig deep excavations. These can be narrow holes for setting in posts or trenches for other purposes such as drainage.
Most of the time digging the ground can be a consistent process. As you dig down deeper soil is normally moist making the work relatively easy.
However, every now and then when digging you may encounter a sizable piece of concrete. Removing buried concrete from the ground can be extremely challenging and awkward at the best of times!
This is particularly the case when excavating out narrow post holes. In this article I will explain what to do if you encounter buried concrete when digging.
This includes some of the best tools to use with tips and tricks of the landscaping trade.
Best tools for removing buried concrete
When it comes to any landscaping task, success relies on using the right tools for the right job. Digging out buried concrete is no exception!
Working loose sections of concrete under the soil can be very challenging. Soil particles can become completely compacted around the concrete making it extremely difficult to work loose.
The tools you will need to remove buried concrete need to serve three functions. These will include excavating out compacted soil, breaking up the concrete and applying leverage to the concrete.
The best tools for digging out buried concrete are:
Digging out buried concrete
The first priority when encountering buried concrete is excavating around the subject.
This will enable you to discover how large and cumbersome the concrete is. As you excavate around the obstruction it will become clear how challenging it will be to remove.
If you have excavated around the concrete and can’t move it in any way you will need to try and break it into sections. First, you will need to get an idea of how large and solid it is.
This can be done by applying the vibration test.
The vibration test
The 'vibration test' involves involves striking the concrete with a bar or chisel to see how solid it is. The best tool for this is with a digging bar.
Once you have exposed the concrete on one side strike it head on. If you feel a strong vibration shock in your hands then the concrete is probably large and deep.
If there is less shock and a hollow sound to the impact then the concrete will be easier to remove.
Expose the concrete fully
Regardless of how large the concrete appears to be you will need to expose the subject fully. This means excavating a trench around the concrete so you can expose it on all sides.
This will reduce compaction around the concrete's mass. If the ground is dry and difficult to dig empty a bucket of water into the hole and wait for it to seep into the soil.
This will help to lubricate surrounding soil particles making it easier to dig. The extra give in the soil may even provide an opportunity to start to work the concrete loose.
Find an edge
One of the most fundamental parts of removing buried concrete is finding an edge. This will enable you to excavate deeply around the concrete which will help you to dislodge it.
The best way to start to work buried concrete loose is by applying leverage to an edge.
The most effective way to apply leverage to the concretes edges is with a digging bar or grafting spade.
Drive the shaft deeply around the concrete and use your body weight to try and dislodge it! Slowly you should be able to see some amount of movement to the concrete.
Once the concrete is moving a tiny amount it is easy to slowly work it lose. Once you have forced the concrete over one side then try to lever it back over to the other side. Eventually the concrete will work itself loose.
You may find you may need to excavate out more soil from around the concrete to dislodge it. However if you still cannot even move the concrete you will need to break it!
The crack technique
Very often it is the case that buried concrete is wide and flat or too large to remove in one piece. In such an event you will need to crack it.
This can be done with a masonry chisel or breaker. You can chip off sections of the concrete but the best strategy is to crack it down the middle.
This allows you to then expose the crack by driving in a digging bar or grafting spade. The long shafts of these tools will provide great leverage to start to move and dislodge the concrete.
Excavate a drop hole
One of the most effective ways to remove stubborn, buried, concrete is using its own mass to your advantage. The best way to do this is by excavating a drop hole.
This involves digging around and under the buried concrete. By creating such an underlying void the concrete becomes easier to move and dislodge.
Digging such a strategic hole can be timely and challenging but very effective! Be prepared to dig slowly and accurately, a digging bar or grafting spade is a good tool for this process.
If the ground is excessively dry and compacted water can always be added to soften it.
Use a breaker
If there is no other way of moving or dislodging the concrete you may require more extreme measures. Breakers are a great power tool for shattering and breaking up buried concrete.
These powerful tools are designed to break and dislodge any dense masonry work. Some of the most convenient are electric hand held breakers.
These are perfect for breaking though previous post holes and awkward underground obstructions.
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Paul Nicolaides has over 30 years of recreational gardening and 20 years of professional landscaping experience. He has worked for landscape contractors including design and build practices across London and the South East. In 2006 he qualified with a BA Hons degree and post graduate diploma in Landscape Architecture. In 2009 he founded Ecospaces an ecological landscaping practice which aims to improve social cohesion and reduce climate change through landscaping. In 2016 he founded Buckinghamshire Landscape Gardeners which designs and builds gardens across Buckinghamshire and the South East. This blog aims to provide easy problem solving information to its audience and encourage others to take up the joy of landscaping and gardening.