STEEL TO CONCRETE BOND

[BigBakwas77]

I am working on a project for replacement of small (5HP) compressors. Vendor shop drawings show light gravity and lateral reactions. (4.5 kN gravity and 2.0 kN lateral max) Existing slab on grade is a, 8" thick concrete with two layers of rebars. I have no concern if the slab will be able to support the new compressor. But the existing slab has heating tubes within, so I am not allowed to drill it through to connect the new equipment to the slab. Existing compressor was glued to the slab. I do not have any experience with gluing mechanical equipment to concrete slab. Can someone with previous experience in this matter point me in the right direction?

 

[canwesteng]

You aren't allowed to use friction to attach things for seismic loading, so need some kind of bond. Can you cast a small housekeeping pad, bond that to existing roughened concrete, and then anchor the compressor to that pad?

 

[BigBakwas77]

@canwesteng
Thank you for your quick reply. I am sure I can propose adding a 8"-10" thick pad on top to the client. But let me get this clear from you how will this work. We will roughen the slab top surface where the pad is to be built and then do we apply some sort of adhesive before pouring concrete for pad? If so, what sort of adhesive would that be?

 

[Lomarandil]

If pouring a concrete pad, you'll use intentional roughening and a cement paste to promote bond between the two layers.

 

[XR250]

If you turn on the heat, you can locate the tubes with an infrared gun.

 

[robyengIT]

once happened to me the same : I used, on the roughened surface of the slab, some epoxy resin (suitable for that job)and, when that resin was not yet hardened, we poured the 2nd slab on top

 

[FloydLloyd]

Here's an old spec that might be useful: ACI Standard 503.1-92, 503.2-92: Standard Specification for Bonding Hardened Concrete, Steel, Wood, Brick, and Other Materials to Hardened Concrete with a Multi-Component Epoxy Adhesive
I have a copy that's 1992, not sure what the current status of the standard is.

https://www.concrete.org/store/prod...rmat=DOWNLOAD&Language=English&Units=US_Units

Prep concrete surface by mechanical abrasion.
Epoxy ASTM C881 type IV
lots of other good spec notes