More and more people are looking for an alternative to the classic wooden fence and are becoming aware of gabion fences. These are wire cages in different sizes and shapes that are filled with gabion stones and thus look like an elegant stone wall. Property owners and gardening enthusiasts who decide to use gabion stones should pay attention to the appropriate stone size and its filling quantity.
Gabion stones in detail
Gabion stones are stone wall variants that are easy to set up and can be set up and filled without any knowledge of wall construction. The fences consist of a wire basket that is filled with rubble stones in various grain sizes, giving the impression of a wall. Not only quarry stones are used here, but also gravel, which is quite coarse-grained and can therefore be used for the gabions without any problems. The following stones are ideal and have established themselves as filling material:
- granite
- dolomite
- Sandstone
- quartz
- basalt
- limestone
- Greywacke
- Ornamental gravel
- Glass chunks (not rock, but often used for gabions)
- marble
- Sugar stone
- Shell limestone
Because of this diversity, it is necessary to know how general filling quantities for gabion fences are calculated, as each stone has a different density and even fracture shape. You cannot order the same amount of marble as basalt because the two rocks are fundamentally different and it could easily happen that you receive too much or too little delivery. This should be avoided at all costs, otherwise you will incur unnecessary costs. The difference between the different gabion stones becomes even clearer when you choose a specific one Desire shape, for example very flat or roughly chipped stones with clearly visible stones Edge.
Tip: Before choosing the stones you should find out in which colors they can be supplied. Perhaps you like a rose quartz in delicate pink tones more than typical greywacke stones, which is important for the respective project
Stone size
The correct size of the gabion stones is crucial for the necessary order quantity, as this determines how close together the stones are in the wire baskets. The size is also important so that the stones do not simply fall out of the holes in the gabion cages as soon as they are filled. For this, the dimensions of the respective mesh size are required, which you should look up when buying the cages to find out the necessary stone size. The mesh size describes the distance between the wires. Typical mesh sizes are:
- 50 x 50 mm
- 50 x 100 mm
- 50 x 200 mm
- 100 x 100 mm
But there are other mesh sizes that range from small 30 x 60 mm to large 150 x 350 mm and also influence the size of the stones. The stone size is measured based on the mesh size. For a gabion fence with a mesh size of 50 x 100 mm, you should choose stones with a grain size that corresponds at least to the shortest width of the mesh. In this case, these would be gabion stones, which have a grain size of 50 - 120 mm, for example, and cannot fall out during filling. However, the size can be influenced by the fineness of the grain:
- Coarse stones: usually larger, further apart, as the edges are more misshapen, fewer stones are required
- Fine stones: thanks to their smoother edges, lie close together, the shape of the stones is consistently similar, more stones are required
You also have to make sure that the size of the stones is usually based on a sieve. This means that the size given is only an orientation, as natural stones are not identical in size, unless they are processed. The following problems can occur:
- The length, width or density of some stones do not match
- these can either not be used at all or only after repeated attempts
- often fall out
- in extreme cases cannot even fit into the fence
This problem does not occur with machined stones that are uniform in shape. These can be stacked in the gabion baskets without any problems, but they do not appear as natural as the other stones. An example of this would be paving stones, even if they are rarely used for gabions.
Tip: If you no longer know what the dimensions of the mesh size of your gabion fence are, you can simply measure them with a tape measure or ruler.
Filling quantities
After you have decided on the right size of the stones, you then have to calculate the filling quantity. This information is important so that you have enough stones available to fill your gabions and the optimal filling quantity saves you time and money. The following quantities are required for the calculation:
- Height of the gabions in meters
- Width of the gabions in meters
- Length of the gabions in meters
- Weight of the stones per cubic meter (m³) in tons
Many people have problems with this because they do not know how much the individual stones weigh. This information is easier to find than you think, because each manufacturer has to specify the corresponding weight per cubic meter for the specific gabion stones. For example, a cubic meter of basalt 60 - 300 mm weighs 1.5 tons per cubic meter, while a cubic meter of Jura chunks 45 - 56 mm weighs 1.4 tons. It looks like a small difference, but it is crucial for the calculation. The formula is as follows:
- Length x height x width x weight = result in tons
That is, if you have a gabion fence with the dimensions 10m x 2m x 1m and the above mentioned Jura If you use chunks, you have to fill 20 m³ of fence, which corresponds to a filling quantity of a whopping 28 tons. Spending between 1,200 and 1,500 euros for Jura chunks in this amount. Please make sure that, despite this exact calculation, you always order around 20 percent more stones, as some can be damaged during transport or not completely the fence due to their shape to complete. It can also happen that more stones are needed to fill corner joints. This is typical for this type of filling and it is therefore important not to forget this point.
The invoice looks like this:
- Result in tons + 20% = final filling quantity
With a quantity of 28 tons, 20 percent corresponds to 5.6 tons and so you end up with a filling quantity of 33.6 tons. The delivery costs differ depending on the dealer.
Tip: If you have problems with the percentage calculation, you can simply divide the result in tons by 5. The result is 20 percent.
Round gabions
When calculating the filling quantity for round gabion fences, it can often be a little more difficult. Since this is not a cuboid, but a cylinder, the filling quantity must be calculated accordingly. Thanks to the circle number Pi (
- Radius of the circle
- Height of the fence
The formula is as follows
- Circle number Pi x radius² x height = volume
With a circular gabion fence with a height of two meters and a radius of one meter, you have a room volume of 6.3 cubic meters. Now you have to calculate this value together with the specific density of the stones per ton, so:
- Volume x weight = filling quantity
If you take the above-mentioned Jura chunks 45 - 56 mm, which weigh 1.4 tons per cubic meter, you get a filling quantity of 8.8 tons.
Hollow cylinder
However, since not every gabion fence is used as a pure cylinder, but rather as a hollow cylinder, you have to use a different formula for this:
- Volume of the outer cylinder - volume of the inner cylinder = volume of the hollow cylinder
With a gabion fence that has an outer radius of two meters, an inner radius of one meter and a height of two meters, you get a room volume of 18.8 cubic meters. Then multiply this value by the weight of the stones per ton and you arrive at the filling quantity. For the Jura chunks already mentioned, that would be a filling quantity of 26.3 tons.
Elliptical cylinder
As a third variant, there are elliptical cylinders, i.e. gabions, which are oval in their basic shape and therefore allow even more freedom in design.
The formula is:
- Circle number Pi x radius of the long side x radius of the short side x height = volume
If the same radii and heights are used as with the hollow cylinder, you get a volume of 13.6 cubic meters. Multiplied by the weight, this results in a capacity of 19 tons.
Tip: Since round gabions are never as accurate as straight variants, you should order between 20 and 25 percent more stones here so that the curves can be balanced out.
