Adhesives (Glues) For Bolting
Ensuring Safety With Correct Product Installation
This is perhaps a bewildering subject in so far as there are many products available on the retail market with standards applicable to civil construction applications only despite many products used for rock climbing purposes.
Adhesives vary significantly in appearance, permeability, dispensing method, reaction time and strength once fully cured. Adhesives used by climbers are ‘borrowed’ directly from industrial fastening applications, so it may come as a surprise that, unlike the anchors, there are no UIAA or EN certifications for the adhesives themselves.
- Gel Time – the period of time in which mixed adhesive can be injected.
- Cure Time – the period of elapsed time required until a load can be safely applied to the anchor.
Both times are important, considering we need sufficient time to install one anchor before ascending or descending to glue in the next anchor and to know when climbing is possible once all anchors are installed.
Faster-reacting adhesives that permit climbing on the same day anchors were installed may seem like the obvious choice; however, operating climate and user experience may necessitate choosing a slower-reacting product.
Note on ETA’s and EOTA
ETA’s are the short form for European Technical Assessment documents and are issued by the European Organisation for Technical Assessment. They provide information about the product and describe its intended use. See the website: www.eota.eu
Construction anchors that are used in “safety-critical applications” where their failure can cause loss of life or serious economic loss are covered by ETA’s. This is very similar to climbing anchors, where a failure can also cause a loss of life. In addition, the EOTA document EOTA GD 002 (Assumption of working life of Construction Products in Guidelines for European Technical Approval, European Technical Approvals and Harmonised Standards) discusses what the design lifetime of construction anchors should be, and a “normal” lifetime is taken to be 50 years.
Whilst many adhesives will achieve acceptable tensile test results with our products, we recommend that developers adopt pure epoxies or vinyl esters as their choice of adhesive. Polyesters have demonstrated poor long-term performance and ultimately lower strength, so it is important to choose premium adhesives given the difficulty with extracting glue-in anchors. We believe that employing adhesives known to perform in the harshest climbing environments is a sound and logical practice.
There is no engineering reason why you should not be able to reasonably expect to get 50 years from a well-placed glue-in anchor, using the right material for the purpose and the right adhesive. The 50 year design life has now been doubled to 100 years in revised standards.
On the subject of slower curing epoxies, the longer cure (and gel) time can be regarded as a disadvantage however glueing in a test bolt at ground level for your first time is an entirely easier exercise than fixing anchors at height thus the advantage of a longer gel time becomes apparent. This is particularly so for those equipping new routes in hotter climates where faster-reacting adhesives can gel in a few minutes rendering their use impractical to most users.
For experienced developers, instead of marking and pre-drilling all the holes first then glueing afterwards, the longer gel time of an epoxy affords time to drill / clean and glue-in each anchor before moving onto the next placement which would otherwise not be possible with other adhesives types that gel fast. This clearly requires absolute confidence in determining placements without pre-marking although with knowledge of the new route gained on first inspection and during cleaning, this strategy significantly improves the efficiency of equipping a new route that would otherwise not be possible without the use of an epoxy.