adhesive for limestone repair?

[Andrew Bodenham]

I'm investigating options for repairing a limestone block (about 300mm cube) which has been split by a hinge pintle corroding inside it.

I'd prefer to keep the original piece rather than source a replacement. Has anybody had experience of bonding stone together with, say, epoxy? I can't see why it wouldn't work, as the two pieces are a very accurate fit and the joint area is large.

A google search has produced a few leads, but I'm thinking of a thin, flowing adhesive rather than a thick goo like tile cement which would tend to hold the joint open.

Any experience or recommendations for suitable products please?

 

[Flyfisher]

I would think the best method will depend mainly on the required strength of the joint, which will depend on the use of the limestone block and orientation of the crack. A horizontal break with the joint in compression would, I think, require little more strength from the glue than to just hold the two pieces in position. I'd guess that a very thin smear (or perhaps a few spots, of epoxy would do the job. A vertical break with the joint in tension (e.g. a lintel-type application) might require a stronger glue/joint, perhaps something like a few helifix rods fixed into drilled holes.

 

[andrew gayton]

stainless steel dowel and a chemical-set type grout into pre-drilled holes.

 

[inwood]

Not sure about this but I used plaster of paris to joint the sections of my fireplace together. Fitted steel rods into each section and then plastered them together. Has set and held very fast. You can buy stone PoP from craft shops and using a runny mix would allow a very thin joint. Not sure if this would be suitable for an external setting though.

 

[Penners]

Surely plaster-of-paris doesn't have much mechanical strength, though, does it?

 

[inwood]

I'm sure you're right. Thinking about it all the joints in the fireplace are in compression so the PoP isn't used for bonding.