Forums: Climbing Information: The Lab: glue in pull test, weird results??: Edit Log


Apr 15, 2010, 7:17 AM

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Registered: Apr 8, 2008
Posts: 351

glue in pull test, weird results??
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well, a friend showed up the day before yesterday at my house with some glue in anchors he wanted to pull test. so we went to a huge boulder (not climbable, just a big rock) near my home, and drilled a 1/2" hole. we had never installed glue ins before, so we did as the instructions said. we drilled a 1/2" hole to install a 3/8" bolt (it was actually 10 mm). then cleaned the hole very well, poured in the glue, and inserted the bolt as if we were screwing it in. the bolt looked like a 100 mm piece of threaded rod, but wa sold as "glue in anchor" for about $1.50 each. then we let it rest for 24 hours.

so yesterday, we went there with my jeep, which has a Warn M8000 winch rated @ 8000 lbs, and weights a little more than 2 tons. we installed a Fixe hanger rated @ 22 kn, and then we oriented the jeep to pull in almost perfect tension, straight out. as i began pulling, the jeep's suspension lowered a lot. then, the jeep began pulling forward, even with the brake pedal completely at the bottom. after the jeep was pulled about 4 feet, i decided it was enough for my jeep, i was actually afraid of messing with the brakes or something. so i stopped the winch. but my friends told me to pull a little more. so i did, and all of a sudden something let go. i was sure the bolt had unglued and was out of the stone. but as i was exiting the jeep, someone yelled "come and see, we broke the hanger!!"

i have read and heard a lot of concern about quality of the rock, quality of the bolts, proper installation, etc. it seems to me that the risk is if you mess with the installation of a good bolt, maybe braking the stone around it, or braking the bolt by overtorque. or, if you install a bad bolt in a good location and with good technique. however i had never heard nor read anything where they mention possibly braking a hanger while the bolt remains intact.

and, the bolt and glue were purchased locally from a hardware store. the glue is like $25 and the threaded rod is like $1.50. yesterday morning my friend got a 1 meter rod of 3/8 SS for $5. so yesterday after braking the hanger, we did another hole and glued a 100 mm piece of that SS. today we are going to pull it to see how it holds...

so, what do you think?? why did the 1 ton glue held while the 22 kn (about 2.2 ton) hanger broke??

heres the video:

EDIT TO ADD: we live in Mexico, and we found the materials locally. and, english is my second language, so if anything is confusing or something, let me know and ill try to rephrase it or explain it better...

(This post was edited by shu2kill on Apr 15, 2010, 7:19 AM)

Edit Log:
Post edited by shu2kill () on Apr 15, 2010, 7:19 AM

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