How clean does my original concrete have to be in my basement to pour an overlay over it?

Question

We had carpet in the basement and had water damage so we had to rip it up, now we have old glue and junk all over the concrete. We were considering putting new carpet down there but were wondering about concrete overlay. Do I need it to be perfectly clean or can I pour the overlay over the messy concrete. How clean does it need to be?

Answer 1

Hi, your floor needs to be fairly clean. If the concrete overlay is going to stick properly, it needs to bond well to the sub-concrete. If the glue residue has hardened, you might be able to remove it with a power sander  that has a very course grade belt. If it is soft, you might be able to soften it even more by using a solvent like Turpentine or Kerosene. (try it in a test area first). Sometimes you can use a bonding agent that will bond the new overlay to the old glue. I usually use a product called Cem-Stick. It sticks to anything and never deteriorates. Just pour it on the floor. spread it around with a soft broom and let it dry (1 to 5 hours). Then you just spread your overlay.

I hope this helps

Answer 2

it has to super clean any dust or debris between the layers will break the bond also you need to apply a bonding agent before you apply the top layer of concrete or the two layers will not bond together