There's two types of concrete. Concrete that has cracked or will crack. Leave it alone.
Question Crack in cement drive way
Seal it using any of the cement-specific products noted above. Having moisture in the ground that may migrate under the slab is far different from having a crack in the slab where water will gather directly under the crack and freeze. IMHO, filling the crack is risk free and simple while doing nothing, while slightly cheaper, may result in more degradation, sooner.
I like the idea of a flexible solvent and then fill it in with concrete. Good luck, but I know nothing about this topic.
No irrigation system here. I do have one at my 2nd and 3rd home... But not this one.
My back cement deck is even worse. Who ever did this job sucked at cement.
Who ever did this job sucked at cement.