Then build a perimeter or a wood brace that is the same height as you want the concrete to be.
Pour concrete over old slab.
When wouldn t i want to pour new concrete over old concrete.
Concrete repair guide aci 546 and guide for concrete floor and slab construction aci 302 1.
A well poured concrete slab with a deep sturdy foundation can last for 30 to 40 years.
Make sure the braces are level and lay down a barrier of wire mesh over the existing concrete inside of the barrier.
The bulk of the work for a new slab is in the excavation and form building.
The condition of the existing slab is the primary factor that determines how long the new concrete will last.
One way is to tap on the slab around any cracks and then in a good area.
The slab should not sound like it is hollow under it or that it is thin at that point.
Then figure on spending a day building the forms and another pouring the slab.
There are cases when pouring new concrete over old just isn t a viable solution.
How to pour a concrete slab.
The surface was badly worn and pitted but the slab was sound and there was ample height to pour a new slab right.
If you have to level a sloped site or bring in a lot of fill hire an excavator for a day to help prepare the site.
Pouring concrete over old concrete instead of directly over a new gravel foundation limits your ability to maximize the slab s lifespan.
You ll find a lot of useful information in two aci reports.
To lay new concrete sweep and clean the old concrete and saturate the old concrete with water.
In the video below i poured a new stamped concrete patio slab right over the old existing concrete.
The old concrete was over 20 years old.
The condition of the existing slab is the primary factor that determines how long the new concrete will last.
Pouring concrete over old concrete instead of directly over a new gravel foundation limits your ability to maximize the slab s lifespan.
A well poured concrete slab with a deep sturdy foundation can last for 30 to 40 years.
If you re concrete has large cracks and the slab may still be moving due to freeze and thaw conditions or settling then a tear out and replace is a better solution.