A well-constructed concrete floor is both strong and durable. Suitable for residential or industrial use, properly installed and well-maintained concrete floors can provide decades of trouble-free usage. But concrete flooring can develop problems, either because it was not properly installed and maintained, or simply because natural wear and tear or the elements have caused damage. While occasionally a problem might require the complete removal and replacement of the floor, most problems with concrete flooring are repairable with a bit of work and the proper techniques.
Levelling issues are some of the more common problems found with concrete flooring. When concrete is poured, it can cure with either an intended slope, or an uneven surface. This can make your concrete floor look sloppy, or create problems when installing a floor on top of the surface, such as linoleum or hardwood floorboards. Unlevel floors can have a number of causes, from unstable foundations to bad levelling by whoever poured it, but an unlevel floor can be fixed.
The easiest way to fix an unlevel concrete floor is by using a combination of grinding and a patching compound. If the problem is a bump in the floor, grinding the bump level with the remaining floor using a grinding machine, available at an equipment rental shop, is the best fix. If the problem is a generally uneven or sloping surface, you can use a patching compound on the surface to create a thin layer of concrete that can be levelled to your satisfaction. Many surfaces will need a combination of the two methods: grinding larger bumps level, and then using a patching compound to create a completely level surface across the entire floor.
After years of use, your concrete flooring may become damaged. Flaking, cracking, even breaks are not uncommon as concrete ages, especially in cold weather climes where concrete goes through years of freeze-thaw cycles. Extreme damage will require replacement, but for minor damage you can often repair the damage--and, if you catch the damage early enough, prevent future damage from occurring.
For scratched surfaces, a regrinding of the surface can often return the flooring to like-new condition. You'll have to go over the surface several times with successively finer-grit diamond-encrusted grinding pads, but the results will not only be the removal of surface scratching, but also the shiny finish.
For chips and light scratches, a patch compound will do the trick. Pour over the affected area, and then level it to the surrounding surface. If the crack is a serious one, or there's an actual hole or break, it's best to fill it with an expansive cement that fills the opened space, and then cover it with a patching compound.