Brush a thin layer of the slurry mixture onto the old concrete.
How to concrete over old concrete.
Smooth the surface using a two by four or float then add texture as desired using tools or a broom.
The surface was badly worn and pitted but the slab was sound and there was ample height to pour a new slab right over the old one.
Pouring concrete over old concrete instead of directly over a new gravel foundation limits your ability to maximize the slab s lifespan.
This old concrete patio was a perfect candidate for pouring new concrete right.
Install the form usually wood form around the perimeter of old concrete surface.
For this to be feasible the contractor needs to pour at least 2 inches thick use smaller aggregate and incorporate reinforcement such as welded wire mesh or fiber mixed into the concrete.
Spread the new concrete over the surface filling the entire area within the form you created.
Concrete is porous so it can absorb liquid.
When i say bond the concrete you are lying on top off needs to be a rough finish like scabbled.
The form shall extend above existing concrete surface based on the designated thickness of the new concrete.
When pouring new mix over old concrete make the mixture stiffer than usual by adding less water.
You could drill holes into the existing concrete surface and insert steel pins and then the mesh on top.
Get the old concrete slab completely wet making sure any cleaning chemicals you used get rinsed off in the process.
Dry up any water pooled over the concrete before continuing.
It was originally poured in multiple sections so it had some seams that looked like cracks.
Brush the slurry over the damp concrete to form an even layer.
Keep spraying it until the moisture runs off the sides instead of being absorbed.
Before you add your new concrete take a large brush and dip it into the bonding slurry.
So if you pour new concrete over the old surface without preparing the one.
If done properly new concrete can often be poured right over an existing slab.
Make sure all of the old concrete has a layer of slurry on top of it before you move on.
As mentioned earlier concrete in itself doesn t have any binding properties to take the load of an additional new layer.
If you are laying pouring concrete over existing concrete there needs to be a bond.
Make sure that the height of the formwork is even.
The condition of the existing slab is the primary factor that determines how long the new concrete will last.
Pouring over old concrete need similar basic formworks that employed with fresh pours.