My house has two different kinds of foundation, The older part is brick-over-fieldstone. The newer part, dug a bit deeper, is poured concrete.
When that extension was added, they added a cinder-block (and dome poured concrete?) bulkhead to support what was retained of the old back wall, seen below with some cabinets sitting on top of it:
As you can see in the next picture, they retained most of the original (loadbearing) foundation wall, just bracing the lower portion. (The wall behind the cabinets is brick; the opening for pipes is looking at the back of thr right-hand cabinet.)
M question is at the far end of the bulkhead where it meets the new poured-concrete foundation wall. Apparently these were construcred as separate units, and there's a thin gap between them:
And the bottom of this crack (sorry, no pic) is my main water infiltration points, when the ground-water level gets high enough. (The major floods in 2010, for example.)
So: What's the right way to seal this? Just try to stuff hydraulic cement into the crack? Caulking? Expanding foam? Something else?
Or would that endanger the brick foundation behind it? (Note that I've never seen any sign of leakage there, so I suspect the additional foot or two of depth in the new section is what puts it below the high-water line.)