We are in the middle of a miniseries discussing concrete floor cracks. Our last episode discussed how to fix cracks in floating floors. But what if a homeowner discovers a crack in a concrete floor and the concrete has started to sink? When they don’t have the money to replace the entire floor, here are the other options.
The first is to break that area of the floor, dig down, compact the floor; perhaps it happened because they didn’t have proper drainage; fix that, add gravel, compact the gravel, compact the ground and then pour new concrete.
You can also pin with metal into the good concrete and pour concrete there.
There is also a more cost effective way to do this. It's called “mud-jacking.” Where the floor is sunk, you drill a hole or a series of holes, create a concrete slurry which is pumped into the holes and you can actually raise the concrete. But if the soil is going to sink again, you haven’t solved much. So you have to make sure that soil is really compacted.
Sometimes you run into a situation where the soil underneath the floor is going to continue to sink. In this case you may want to use a technique called “foam-jacking.” This is very similar to “mud-jacking” except polymer foam is used. A series of holes are drilled and the foam liquid is pumped in. The foam penetrates the soil making it denser and more compact, and raises the concrete.