concrete over existing concrete floor

[dylnlc]

Hey guys I have a shop that im working on and im needing some help on what to do. The shop is split in two sections that has a ramp leading from one to the other. I am trying to split them in two different rooms and was wondering what your thoughts were on pouring over the existing concrete. The floors have about a 3 inch difference between the two. Thanks for your advice in advance!

 

[ConCretin]

you should be fine placing 3" of concrete over an existing slab. The only question is whether and how you should bond the new placement to the old.

This depends on the condition and surface of the existing slab. What can you tell us?

 

[Edger]

2 inches is the minimum for concrete so 3" should be OK. Can you use steel fibers to strengthen it, can you drill and fit steel dowells into the existing slab. I am no expert for concrete, but it would appear to me that you either make the mix strong (steel fibers & dowels) or you adhere it to the existing slab with epoxy. Maybe others with more experience might think 3" is enough by itself.

 

[dylnlc]

Well ive asked a few people and they all say its ok as long as its 3 inches deep but i just dont know about the top of the ramp where it will only be a 1/2". I think im going to have to break it all out and start over...

 

[tncatadjuster]

If you shotblast, and use the proper epoxy it would be fine, if executed properly.

Do it on the cheap, and fly. Good concrete is great, shoddy concrete is well...

 

[ConCretin]

Here's the deal. It's less about the thickness of the overlay than it is the condition of the substrate. If your existing slab is sound i.e. no cracks, you want to bond the overlay. If the existing slab is cracked and is still moving, you want to isolate and strengthen the overlay.

 

[Edger]

I would have thought that 3 inches butted up to the higher slab is better than a tapering edge. You need to cut and jack hammer out the butting edge. If it is normal concrete, below 2 inches will crumble away.

 

[dylnlc]

Ok thanks guys for the information. I think im about to start a BIG project..... o well I have to learn somehow!!