"Puddle" Concrete Construction 2

[chamokinawan]

Anyone know what "puddling" is in concrete construction. It was a term used in a webinar today in the context of high strength concrete columns. It seems to be a way of continuing the strength of the concrete column through a slab. Thanks in advance.

 

[JAE]

In that sense, puddling would be the practice of placing concrete in the floor area directly over and within a set perimeter around a column.

Columns sometimes use higher strength concrete than the floor and there is concern over the section of concrete in the floor within the column "footprint".

ACI, for example, limits the difference between column and floor concrete strengths UNLESS you puddle the higher strength concrete into the floor over and around the column.

The lower strength concrete is then immediately placed in the floor around this puddled area with the two types of concrete mixed/vibrated together such that there is no cold joint formed.
Timing here is very important.

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[JAE]

If you are using ACI 318 - see section 10.12.

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[KootK]

When you use column concrete stronger than your slab concrete, you can get a situation where bearing capacity is a problem for the column concrete that is cast along with the slabs at a lower strength (the slab strength). Within limits, codes allow you to puddle a blob of higher strength concrete around the columns when the slabs are poured to solve this issue. Contractors in my area hate this and we add extra vertical rebar dowels to the joint instead.

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.