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testing 2 - coachscrews plus glue 24-Nov-2011 At 6:57:13 AM cruze

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I would be interested in knowing whether any of the glues have been demonstrated to contract/expand over time. Epoxy resins produce polyether polymers with variable hydrophilicity/swelling profile, polyurethane adhesives likewise. Particularly as a function of surface moisture content which seems to me to be a significant variable in porous rock types such as Sydney basin/Blueys sandstone.

It seems that people use glue types interchangably when bolting depending on what their mate uses and what they can get cheap, but perhaps don't consider what happens at the rock-glue interface (or even the metal-glue interface although this is probably less important with threaded metal) over time. Given that this interface is where maximum surface contact is desirable any contraction (or expansion/contraction cycling in soft rock) would be likely to affect strength quite considerably, wouldn't it? In other words strength after 1 hour is only part of the picture.