How do you repair a crack in slab?

To repair a crack in a concrete slab, first clean the crack thoroughly by removing any loose debris or dust. If the crack is wider than 1/4 inch, fill it with a concrete repair caulk or epoxy filler, ensuring it penetrates deep into the crack. For smaller cracks, a concrete resurfacer or patching compound can be applied. Finally, smooth the surface and allow it to cure according to the manufacturer's instructions.