Can a concrete slab/foundation with crack be repaired without repouring a complete new foundation?
If the crack is not active (getting larger) you can fill it with various materials, including masonry caulk. repair would be similar to this: http://www.thisoldhouse.com/toh/how-to/i… As for laying a thin layer of material over the floor to level it, consider something like self-leveling underlayment. This is a cement or gypsum-based product that is mixed into a slurry and then poured over a floor and then spread with a squeegy. The material is liquid enough to level itself out and form a smooth surface, then dries very hard. Various companies make such products; one is noted below. Always check with the manufacturer to see what surface prep they recommend for filling cracks.
