epoxy vs. expansion
epoxy vs. expansion
(OP)
Could someone help me understand when to use epoxy and when to use expansion anchors for masonry or concrete?
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RE: epoxy vs. expansion
RE: epoxy vs. expansion
1. Overhead applications. You can google the Boston Big Dig Tunnel collapse for information regarding epoxy creep when subject to a constant tension load.
2. Where the anchors need to be installed immediately. Epoxy anchors need some time to set. However, you can get epoxy which sets in less than 1 hour.
3. Where fire-protection is paramount such as steel frame structures which are fixed to and prevent concrete wall panels from falling outwards. I am yet to see a compliance certificate for epoxy used in post-installed anchor situations where it has been shown that the epoxy can withstand exposure to high temperatures for a prolonged period of time.
RE: epoxy vs. expansion
I agree with the other comments above too.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: epoxy vs. expansion
A clear conscience is usually the sign of a bad memory
RE: epoxy vs. expansion
RE: epoxy vs. expansion
Good point. I know of some engineers who are specify pull-tests for epoxy anchors (say 1 in every 10).
RE: epoxy vs. expansion
Keep in mind the method for drilling the holes - core-drilled holes have smoother walls and will affect the effectiveness of the anchor.
Ralph
Structures Consulting
Northeast USA
RE: epoxy vs. expansion
With epoxy, you can use 316 stainless steel threaded rod. Some of the wedge anchors that have been certified for "cracked concrete" are 304, but not 316.
RE: epoxy vs. expansion
Further to your point about epoxy + high temperatures, what are your thoughts on welding to chemset bolts (ie. column baseplate welded to chemset hold down bolts) assuming the hold down bolts are low carbon steel that can be welded.
The temperature passed through the epoxy during the welding process is high, but over short period. Would you consider this to ruin the epoxy?
I have seen this done on site before.
RE: epoxy vs. expansion