If a slab has lifted or sunk, has cracks that run all the way through and keep widening, or is flaking across a large area, it usually needs to be torn out and replaced, because the problem is the base underneath. Small, isolated cracks or a single damaged section can often be repaired or replaced on their own.
Signs it is time to replace
- Slabs that have lifted or dropped, leaving an edge you could trip on
- Cracks that run all the way through and keep getting wider
- Surface flaking or pitting across a big area after winters of salt and ice
- Water pooling against the house or garage
- A slab broken into separate pieces
When a repair can work
One problem area can often be cut out and re-poured without redoing the whole slab. Hairline surface cracks that are not moving are usually cosmetic. The deciding question is whether the base under the concrete has moved; if it has, patching the surface will not hold through another Iowa winter.
Why Iowa winters break concrete
Water gets into cracks and under slabs, freezes, expands and pushes the concrete up. When it thaws, the slab settles unevenly. A few winters of that and slabs lift, sink and crack through. Road salt adds surface flaking. That is why tear-out and replace is most of the concrete work done in Des Moines.
