The Void
You will see two things here, one is the hole cut into the concrete to inject the mud or mortar under the slab and into the void, and two the void itself. As you can imagine it is difficult to take photos underneath a slab of concrete, but I think you can get an idea.
Size of a Mudjacking hole
This is an example of the size of a mudjacking hole. You will see in this photo album the size of the POLYLevel hole is the size of a penny.
Down into the Void
The material used in mudjacking is generally some sort of concrete mud or mortar. Because of the nature of this material it is prone to washout over time. In this photo you can see the mud or mortar has mostly washed out from under this drive way slab of concrete
Concrete Slab Dropped
Because the lifting material washed out, the slab has dropped back, and dropped back below its original position before the first lift.
Concrete Driveway Slab Drop Causing Secondary Damage
This photo shows a crack in the driveway because of unequal pressure on the slab due to the mudding or mortar lifting material washing out from under the slab.
Un-Even Concrete
This photo show uneven concrete. It is cause from the concrete driveway slap closest to the garage dropping. This side has actually lifted up and is now a trip hazard.
PolyLEVEL hole size for Injection
In this album you will see the large Mudjacking hole. This photo show the size of the hole is approximately the size of a penny. Once the hole is filled it is small enough that it nearly disappears.