What is the solution to replacing bolts in the future?

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Messages 61 - 65 of total 65 in this topic << First  |  < Previous  |  Show All  |  Next >  |  Last >>
deuce4

climber
Hobart, Australia
Aug 25, 2016 - 11:53pm PT
Here's my 1988 "treatise" on 1/4" bolts.
http://www.bigwalls.net/climb/bolts.pdf
clinker

Trad climber
Santa Cruz, California
Aug 26, 2016 - 07:42am PT
ps - I made those orange etriers I am clipped into way back in 1974!

Bruce, I hope your harness is newer ;-)
WyoRockMan

climber
Grizzlyville, WY
Aug 26, 2016 - 09:17am PT
Single-stem bolts have a unfortunate characteristic that very occasionally they come slightly loose, we call these "clickies". I´ve seen five in my time.


I suspect this is a result of the resin distribution within the hole.

I've pull tested thousands of resin rebar bolts (spent a few years doing geotechnical work in underground facilities). Bolt failures below the rated strength of the bolt are always due to either; insufficient rock strength (poor choice of placement) or improper resin distribution (usually not enough, crews will try to use less resin as a shortcut to speed). A typical resin rebar bolt is 22mm put into a 28mm hole, leaving a 3mm annulus for the resin. These bolts are much larger than we use climbing but the installation principle is the same. Full resin encapsulation is key to proper strength.

The smaller annulus (by proportion to bolt diam) used in recreational setups is an issue to achieving full strength of the system.


JimT

climber
Munich
Aug 27, 2016 - 04:53am PT
Yes and no! All the bolts we´ve removed were correctly installed and we assume the ones we couldn´t were also, we know the people involved. the hassl is the problem is so rare and occurs years or even decades after the installation that there´s no real way to get a common factor. We´ve tried to replicate it in the workshop with repeated heat cycles with no result.
The resins used are for up to 2mm gap and all the holes were the correct size except for some which were smaller. It´s a bit annoying though, you install a couple of thousand bolts and one decides to move after 5 years!
All we can think is the relative temperature when they were installed compared to expansion of the rock in the sun makes them come a bit loose and the elasticity and shrinkage of the resin plays a role.
ionlyski

Trad climber
Polebridge, Montana
Nov 22, 2017 - 10:27am PT
The link to the Access Fund conference held in Vegas and posted upthread does not work. Anybody have a current URL?
Thanks,
Arne
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