What is a Chemical Anchor?
"Chemical or resin anchors are generic terms relating to steel studs, bolts and anchorages which are bonded into a substrate, usually masonry and concrete, using a resin based adhesive system. Ideally suited for high load applications, in virtually all cases the resulting bond is stronger than the base material itself and as the system is based on chemical adhesion, no load stress is imparted to the base material as with expansion type anchors and are therefore ideal for close to edge fixing, reduced center and group anchoring and use in concrete of unknown quality or low compressive strength. Although there are many differing variations and delivery systems in the market, all systems operate using the same basic principle with the base resin, requiring the introduction, by mixing, of a second component to begin the chemical curing process, hence the term chemical anchor." citate:constructionfixings.com
It is often difficult for someone new to resin anchors to understand the difference between the array of resins available. For those who specify anchors it is also important to understand this difference to ensure any specification changes are to truly equivalent products.
- Unsaturated Polyester
- Epoxy acrylate also know as Vinyl ester
- Pure epoxy
- Hybrid systems
Unsaturated Polyester - chemical anchor
This is the classic reactive resin used for the production of 2-component injection mortar, whereby both unsaturated polyester resins dissolved in styrene (the original resin type) and styrene-free unsaturated polyester resins with styrene related monomers as a reactive solvent are used. The 2-component injection mortars made from these resins are fast and easy to use and are characterised by a limited chemical resistance ( in alkaline and other media ).
Epoxy acrylate - chemical anchor
These classic vinylester resins and the 2-component injection mortar made from them combine the good thermal and mechanical properties of epoxy resins with the easy and fast processability of unsaturated polyester resins. Vinylester resins of the new generation are styrene-free, whereby dimethacrylates are used as reactive solvents. The Vinylester resins and the reactive resin mortar made from them are charcterised by, among others, a very high chemical resistance, especially in alkaline media.
Pure epoxy - chemical anchor
There are various options when it comes to selecting epoxy resins and the respective hardening components, which in turn enables an exact determination of the properties of 2-component injection mortars manufactured from the two components to be determined exactly and adapted to suit specific requirements. Hardened 2-component epoxy resin injection mortars are characterised by very good thermal and mechanical properties and an outstanding resistance to chemicals. The amount of shrinking due to hardening is very low, and good compound properties achieve outstanding load values in diamond-drilled drillholes and larger annular gaps.
The informed selection of resin anchors is very important to ensure safe and long lived fixings. This selection can be difficult when the properties of the different types of resin are not fully understood. Once this is clear however it enables the best and most suited product to be used. Once a particular type has been selected it should only be changed if the key application characteristics are still satisfied by the proposed alternative.