The most common reason for cracking concrete is because the subsurface has become compromised. The soil, sand, gravel, or whatever the base is comprised of, has washed out or has settled. This creates a void underneath the slab so there is no longer as any support. Any weight on this slab will now cause it to crack. Over time the crack will grow larger and the slab will start to sink.
This can also happen to concrete control joints. If the subsurface gets compromised and the concrete slabs are no longer supported underneath, they will sink. This causes both a trip hazard and damage to forklifts trucks wheels.
THE SOLUTION
The good news is there is a much simpler solution than the "old school method" of cut-out and re-pour the slab.
If the concrete slab hasn't settled or has only settled a little, then we can drill holes and inject a structural foam to fill the void. The foam is waterproof and is capable of supporting the concrete slab and it's heavy loads.
As for lifting the slab, we use a pressurized system to inject a similar foam. As the foam expands, and the void fills up, the pressure lifts the slab back to its original and now permanent position.
REPAIRING THE CRACK OR FILLING THE CONTROL JOINT
Once the slab has been stabilized, now it's time to repair the crack or fill the control joint with Flash Floor, a faster and more durable solution compared to cutting out the old concrete and re-pouring it or filling it with cheap epoxy. Flash Floor is the best method for repairing any indoor concrete. [For outdoor concrete or asphalt repair we use Flash Track.]