Retaining Walls and No Fines Concrete (NFC)
- First of all, what is No Fines Concrete (NFC)?
- Basically it is just what the name suggest, concrete without any fine aggregates or sand. It consists of generally an aggregate (gravel), cement and water. The aggregate is coated with the cement slurry binding it together, it dries with the strength of concrete but with voids or air pockets. This makes the NFC light weight and allows water to pass through its honeycomb texture.
- NFC can either be mixed on site for smaller areas or purchased from a reputable concrete supplier and trucked in for larger commercial applications. NFC is mixed at a 6:1 ratio by volume of 20mm max size clean aggregate and cement. Water content should be such that the cement slurry evenly coats the aggregate and retains a wet/glossy appearance without excess slurry running off, this is typically around 40 litres per 100kg of cement.
- With the use of NFC we are able to build Block Retaining Walls in areas and situations where normal construction methods would not work. Some of these situations are:
- In areas where excavation behind the wall is limited either due to being on a boundary or close to other structures or footings.
- To construct a wall to a greater height than standard gravity wall construction methods
- By using NFC you are basically increasing the depth of your retaining wall. Most masonry blocks would be an average depth of 200-250mm, by using NFC you are increasing that depth of your solid masonry block from 200mm up to 500mm (Infill depth) or more depending on the height of your wall.
- It is always recommended that every third or fourth block should have part of the back edge removed. This would give a far better adhesion tying the NFC infill layer and the NFC core filled blocks creating a far stronger structure.
- Contact your nearest Australian Paving Centre for your friendly free advice on how to use NFC.