Feild Stone Church Retrofit

[ewing]

Hello
I am working on a project that is an existing Church Steeple. The steeple was built in 1912 with cut stones on the outside and field stones on the inside. Does any one have any locations that I could look for compressive and tension strengths of this comdinations of materials. My present solution is to treat the stones as filled masonary blocks.
Thank you for your time.

 

[Ron]

The properties of natural stone may be quite variable. You might consider coring the materials in a discreet location and having tests done on the stone. I would be equally concerned about the integrity of the mortar. There are few reliable tests for mortar...none that I know of for your configuration. You might resort to a "scratch" integrity test for the mortar. This is my own scale that I have tried to maintain over the years, though it has not been correlated to actual compressive strengths (just a subjective measure)....

(1) Friable, able to scratch with fingernail....< 300 psi
(2) Able to easily scratch or dig with knife blade under light hand pressure....300 to 600 psi
(3) Able to score surface with knife blade under moderate pressure.... 800 to 1200 psi
(4) Able to score or mark surface with knife blade but not penetrate... > 1200 psi

If you can break off a piece of the stone you can run a point load test on it to get an idea of its compressive strength.