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What is considered an "intentionally roughened surface" per ACI318?

What is considered an "intentionally roughened surface" per ACI318?

What is considered an "intentionally roughened surface" per ACI318?

(OP)
ACI 318 states for the purpose of shear friction the interface of hardened concrete should be roughened to an amplitude of at least 1/4".  Does this need to be done using a tool?  or can the surface be considered roughened if no finishing work is done and it naturally cures such that the aggregate extends out 1/4"?

My feeling is that the statement "intentionally roughened" means it needs to be done with a tool.  I'm looking at a case where a concrete corbel is cast separately and "mucked" in to a concrete wall or spandrel pour in a precast plant.

RE: What is considered an "intentionally roughened surface" per ACI318?

I think the idea is that there is a concrete paste & aggregate variation in surface throughout the face with 1/4" amplitude "waves" occurring in a high frequency.  I have always viewed this as either done by hand during concrete placement (with a tool) or chipped at afterwards.

 

RE: What is considered an "intentionally roughened surface" per ACI318?

Can be "raked" with tines just before concrete sets or roughened with scabbling tool after curing.

RE: What is considered an "intentionally roughened surface" per ACI318?

The intention with that 1/4" amplitude is that it occurs at a frequency between 1/4" and 3/4", so you don't get the rough protruding parts occuring too frequently or not often enough.  In that sense, you're (intentionally) creating a roughened surface with specific parameters instead of just saying unfinished concrete is rough enough.

RE: What is considered an "intentionally roughened surface" per ACI318?

I have seen it done with a good ole' garden bow rake.

RE: What is considered an "intentionally roughened surface" per ACI318?

Ive seen them rake, chip, and in a couple of large jobs, they sprayed retarder and then hosed the loose material off after the rest had set up.

Michael.
Timing has a lot to do with the outcome of a rain dance.

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