Concrete foundations can be repaired by replacing the damaged concrete with fresh concrete. The fresh concrete is then troweled smooth to match the existing surface. If a foundation has cracks or other damage, it's important to fix them before repairing the foundation with fresh concrete. Cracks in a foundation can let water and moisture seep into the foundation, which can cause further damage and weaken the structure. Foundations should also be checked for settling every few years, as this can also cause damage to the foundation. If a foundation has settled, it may need to be raised up or corrected with additional supports.

To repair a concrete foundation, you will need to remove the damaged concrete and replace it with fresh concrete. You can use a chisel and hammer to remove the damaged concrete, or you can use a power saw to cut it away. Once the damaged concrete is removed, you can use a trowel to smooth out the surface of the foundation. Then, you can mix up some fresh concrete and use a shovel to spread it over the foundation. Finally, you can use a roller to smooth out the surface of the fresh concrete.