I need to solicit advice from the collective.
We are in a townhouse development that is about six-years-old. I happen to be on the board. We have a situation where the concrete slabs that make up the sidewalk at the entrance to about twelve of the units have sunken into the ground. This has left a gap between the pre-cast concrete steps and the sidewalk that varies from 1 to 2 inches. The steps are attached to the building foundations and they have not moved. It is clearly a problem with the slabs sinking into the ground.
We have been looking at the repairs and we have two options.
The first option is to have the slabs broken up and removed. Then, have new slabs poured.
The second option is to have the concrete raised. From what I understand, it is also called mudjacking. This is a process where holes are drilled in the slab and a slurry is pressure fed under the slab to raise it up. This approach is much less disruptive and considerably less expensive than option one. Any experience with this? Any things to look out for?
Thanks.
Here is a video that shows how it is done.
http://youtu.be/inTMdUt41lM