the crack was caused by a deteriorated sewer line, the foundations were wet and the corner of the building settled. I put crack monitors on and watched it for a year. The movement has stopped once the sewer line was fixed and the soils dried out. The soils were drilled on both sides of the wall and found to be fine a couple feet down.
The core would be used to determine if the epoxy bonded to the CMU and grout. If it broke at the epoxy/crack repair, no good. I found a spec on the SEAINT website, which discusses coring but says it may be waived in some situations, but I'm not sure which situations...
I think, given your information, that it depends on the importance, do you need to transfer stress through the repaired crack or is the repair for appearance only. If, as I imagine, the surfaces inside the crack are rough, there should be some mechanical interlock even if there is a lack of bond.
Michael.
Timing has a lot to do with the outcome of a rain dance.
