Slab depressions in CJ layout

[MillR]

While providing a 3rd party QC Review, I am now engaged in a "friendly" argument with the EOR regarding CJ layout. My comment was: "Review the CJ layout and consider treating slab depressions as edges or re-entrant corners and keep spacing around 36t max."

It looked to me that the slab depressions were added to the drawings last minute, after joints were placed, and then ignored - which is okay, these are just progress drawings and I know the architect was moving things around. But now a joint falls a foot from a parallel depression edge, or L shaped slabs are created, or trapezoids. To me, it would be better to not show the joints at all than to give this kind of direction. He's digging in that it's fine as is. I'm not enforcement, just review, so ultimately it's up to him to take responsibility, but I'd like to be clear for myself.

I concede that 36t is a judgement call. Thoughts about the depressions?

 

[KootK]

I'd be inclined to agree based on the information provided.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[DETstru]

I'm not sure I agree.

If you were to saw cut the slab right at the edge of the depression would this mess with the cutting process? Your saw is "sliding" on two separate surfaces. Though I've never used a concrete saw myself so I can't say with certainty it's a problem.

Also, could trying to cut that perfect line right on the slab depression cause spalling or other unintended damage to the depression edge? Again, I'm not sure but just trying to play devils advocate.

 

[Ron]

MillR...you are correct. If you have depressions in a slab, start the layout there. They create re-entrant corners and cracks will develop if you don't consider them. Your rule of thumb, 36t is maximum in my opinion. Keep them between 24t and 36t, and specify that they be cut the same day as placement.

 

[hokie66]

After you have given your opinion to the EOR, best to mind your own business. This is not an important issue, so why fight about it?

 

[MillR]

Thanks Ron, I needed the "of course". And yes, to hokie, I've got no interest in arguing, just starting to second guess.