The video is about a homeowner's question on whether it is possible to pour a new concrete slab over an old one. Greg a home remodeler, has never had good luck with this method. He has only done this once before on a room addition and it was okay, but he would not recommend it for patios, sidewalks, or driveways.
The problem is that the new concrete will usually crack around the perimeter of the old slab. The thicker the new slab, the less likely it is to crack. Some people recommend using bonding agents or rebar, but Greg is not convinced that this would eliminate the possibility of cracking.
He recommends removing the old slab and pouring a new one if you want to avoid cracking. However, if you need to raise the height of the slab by more than a few inches, you can pour over the old slab by adding sand and then pouring a new slab with rebar.
