IF the cracks are current and STILL moving, no matter how much reinforcing cement you put in there, it's gonna still move and probably collapse.
Now, IF the cracks look 'old' and they aren't getting any bigger, you can buy a cement caulk. Yes, caulk. Buy a few tubes and ask if you can return any unused tubes.
What I'd do is FIRST, put in a 'bead' that's BELOW the surface. Let it harden. Now, you have a 'back' to help keep your SECOND bead from dripping back. Read the tube for wait-times between beads.
My best to ya and hope this helps.
Jay J -Moderator
PS: IF the cracks are letting water in, you have other problems ...
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