Chemical anchors can often be overlooked when searching for a fixing solution as users shy away from these seemingly complicated products; when in reality an exceptional fixing performance can quickly and easily be achieved with benefits which outweigh the traditional methods.
Unlike the widely used but intrusive expansion anchors or plastic plugs, chemical anchors make the fixing an integral part of the substrate as the load is spread throughout the entire area, removing the stress caused within the substrate when these anchors or plugs are ‘tightened’ up.
Because chemical anchors flow into the hole they allow for an infinite combination of diameters of fixing and setting depths, and provide a far greater surface area which spreads the load more evenly and re-enforces the fixing area.
Chemical anchors are usually based on a two part product, combining a ‘resin’ and ‘hardener’ packed together in the required ratio to provide rapid curing (usually 10 parts resin to one part hardener).
Traditional products use a co-axial cartridge where the resin is packed into a cartridge which contains a central inner section that holds the hardener. Application is carried out using a special co-axial gun and a ‘mixer’ nozzle that blends the two parts together before they reach the end of the nozzle.
A more convenient and easier to use packaging format, available on some anchorset products, is the ‘twin bag’ system, where the contents are contained in two separate polythene bags in a one piece cartridge that allows application using a standard sealant cartridge gun; and also provides a much easier flow.
How are they used?
The hole is drilled to the required diameter dependent upon the threaded bar to be used, and the loading it has to take. Full tables of relevant hole diameter sizes and loading strengths can usually be found on all packs and technical data, but for example for an M8 fixing a 10mm diameter hole would normally be used in concrete.
Where are they used?
In addition to the more critical structural applications chemical anchors also provide a more robust fixing solution in many day to day building applications such as:
- satellite dishes
- heavy pipes
- sanitary fixings
- wall ties
- fire surrounds
- steel structures
- kitchen wall cupboards
- towel holders
What types are there?
There are several different types of chemical anchors, with the most popular being polyester resin and polyester styrene-free resin.
A general purpose economical resin based on styrene, recommended for external use due to its hazardous nature. Products such as Anchorset Red 300 or Red 380P from Everbuild are great examples of this type of product and are ideal for medium duty applications; offering a fast cure hardening in around six minutes and taking full load strength in only 30 minutes. This type of chemical anchor would typically achieve 67kN pull out strength on an M12 threaded rod in solid concrete.
Polyester styrene-free resin
Styrene free-resin is the safer option with a low-odour formula making it ideal for both internal and external use. Everbuild’s Anchorset Green 150 or Green 300 are classic examples of a styrene free product providing a chemical resistant finish. This type of chemical anchor would typically achieve 67kN pull out strength on an M12 threaded rod in solid concrete.