The correct rock infill is required, in terms of quality, shape, hardness and size.
We offer you specialized support regarding the appropriate rock type to fill your gabions and river mattresses. It is necessary to take the time ensuring that the rock provides the best solution for the installation. Experienced advice is offered regarding the best rock specifications for your particular needs.
Rock for gabions must be un-weathered and solid type without flaking or excessive weathering.
Correct size :-
Gabions – 100-250 mm minimum (0.5 and 1m high baskets).
River mattresses – 100-2/3 the mattress thickness(to achieve at least two layers of rock).
Do not use smaller rock fragments on the surface of either gabions or mattresses in river course situations. As the high water speed will remove any material that can pass through the mesh opening. Try to ensure that the rock size used is always a bit bigger than the hexagonal mesh opening.
You may use smaller rock within the centre of a gabion basket, this should not be a large amount so that the strength of the filled gabion is compromised.
The use of softer rock and brick fragments to fill gabions or river mattresses are not reccomended due to their water absorbing capacity and thus soften over time, flat rock particles are usually inadequate as they do not provide the same mechanical interlock within the gabion which is found using blasted angular rock, rounded river rock can be used, however is can harm the environment after removal and it is much more difficult to obtain a flat gabion facing during erection of the gabion facing.
Rock density necessary for gabions and mattresses should be a minimum of 2.6 tons/m3, normally offering a void ratio of 35%. When you add the 35% for waste/fines when dump rock is ordered we recommend ordering 2 tons of rock per m3.
During gabion erection rock should be placed as close to the infill position as possible, when offloaded from the truck to reduce time wasted re-handling the rock into the final position on sites.
Labor rates allowed for are 1-3m3 per man per day, however to be realistic generally allow for 1 man/m3/day.
Rock supply, manual labor prices and gabion/geotextile amount to approximately 33% each of the final completed gabion cost, for PVC coated baskets, we suggest allowing about 20% extra to the overall cost of Class A Galvanised gabions.
Different coloured and types of rocks are available, depending if the wall is in the dry or wet situation.