Over Existing Concrete?
In most cases the solution is YES! If the present concrete is structurally sound, isn’t heaving or sinking, then you’ll be able to pour concrete over concrete.
My rule of thumb is this:
If the new concrete is three inches thick or additional – you do not ought to bond the new concrete to the recent concrete. If the new concrete is a smaller amount than three inches thick – you may wish to use a bonding agent to bond the new concrete to the recent concrete. Make sure the concrete is clean, wash it or vacuum it, do not pour over any dirt, dust, detritus or loose concrete.
What’s the minimum thickness you’ll be able to pour new concrete over concrete?
In most cases, I do not wish to pour associate degree new concrete but a pair of inches thick over a recent, existing concrete floor, slab, patio, or road. Two inches thick (or more) provides you adequate strength for a wear surface, particularly if you are driving over it.
Although it’s attainable to pour one.5 inches thick with a pea stone combine, I do not suggest running that skinny. If that is all the peak you’ll be able to afford to lose, it’ll work however you will develop additional shrinkage cracking than traditional thanks to it being therefore skinny.
A solution for that’s to saw cut some additional growth joints to assist minimize any shrinkage cracks if you are involved in this.
And bear in mind, if you are new concrete pour is a smaller amount than three inches thick, you may wish to BOND the new concrete to the recent concrete employing a bonding agent.
When would not i need to pour new concrete over recent concrete. There are cases once running new concrete over recent simply is not a viable answer. If you are concrete has massive cracks and also the block should be moving because of freeze and thaw conditions or sinking, then a tear out and replace could be a higher answer.
If tree roots are inflicting your concrete to crack, then tear out the recent concrete, resolve the tree roots drawback, and pour new concrete.
What if my recent concrete includes a heap of cracks in it?
If you are existing concrete includes a heap of cracks, however is structurally sound, is not moving, heaving, or sinking, then it’s okay to pour new concrete over it. I recommend putting in a bond breaker between the recent block and also the new one that the cracks will not transfer up through the new concrete.
Some of the items we’ve got used as bond breakers are:
- Plastic textile
- Typar house wrap
- Roofing felt paper (tar paper)
- Thin layer of sand
- Thin layer of crushed stone
- Thin layer of Styrofoam
Using a bond breaker can keep the 2 blocks of concrete separate and also the cracks won’t mirror up through the new slab. You’ll still have to be compelled to saw cut or groove growth joints within the new block to assist management shrinkage cracks, rather like you’d any new concrete pour.