Friday, September 28, 2007

Re: Epoxy for Wood Repair

I have been unable to find an adhesive product which provides any sort of quantitative value for shear or bond strength with wood products. I have used urethane glue for assemblies, but have nothing other than anecdotes on its performance. My experience, although good, is only with thin films of the adhesive, clamped during curing. It's bond strength appears to be higher than nearly every hardwood I've seen it used on, up to and including white oak, santos mahogony and brazilian walnut (aka Ipe or Ironwood, G>1.0, E probably over 2.0E6, again anecdotal). I would not trust urethane in anything other than thin film applications. 

Someone else mentioned WoodEpox. I have seen it used for rotted/damaged wood repair in non-loadbearing and compression-only repairs. I received some correspondance fromt he manufacturers, who would not give any shear or bond capacities, stating that it is only to be used in compression.  Most commercial high-strength epoxies will require a specific film thickness, surface preparation and curing requirement, none of which could be easily controlled in your in-service condition.

In your case, check to see that you get some kind of data on the cured epoxy (compressive and shear moduli for bulk epoxy) to ensure some modicum of compatibility with the anticipated future deflections. Then make sure the bolts hold everything together structurally.
Jordan


ASLCSE@aol.com wrote:
Hello again, engineering friends.
 
What is the best suited EPOXY to use in Wood Repair (cracked DFL beam) in "combination" with bolts holding it together.
 
Thanks
 
Antonio S. "Tony" Luisoni
Consulting S.E.
Granada Hills, CA




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