Footing poured in two steps 2

[ml13]

I get a call today from a contractor on a job we are doing. They began pouring the footing for an 18' retaining wall earlier in the day (90F and sunny). The ready-mix trucks stop coming at about 2pm after getting only 10" down of the 20" thick footing. They finally get a hold of me at home around 4:30pm. At this point the concrete has hardened sufficiently that there will be a horizontal joint at mid-depth when the fresh concrete arrives (the site super was standing on it).
My initial concrens:
1. Will the wall dowels (#9@10) be able to develop fully?
2. Will the top bars in the footing be affected? My "d" went from about 17.5" to about 7.5". Or did it? Will the horizontal shear between planes be adequate to "activate" the bottom half.
3. Generally speaking, should the engineer make a decision on the fly, over the phone, about whether to continue the pour? Or is this purely the contractor's responsibility? If I give him an opinion that is wrong (either keeping it or scrapping it), will I be liable?

In the end, the super decided to cancel his order and start cutting out the concrete before it completely hardened.

Was that the right decision? Opinions, please.

 

[CSEllc]

I'm glad to see the contactor decided to start cutting out the concrete before you told him to.....or at least I would have told to remove it and start over.

You might be able to justify not removing the footing by adding pins and dowels but I would not feel comfortable with this solution.

In my opinion the contractor did the right thing.

 

[Focht3]

Good contractor - wish more were like him. He made the right call.



Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora. See faq158-922 for recommendations regarding the question, "How Do You Evaluate Fill Settlement Beneath Structures?"

 

[SlideRuleEra]

Good decision by the contractor.

Suggestion for future reference: As an Owner's representative I had many occasions similar to what you have described. The best way that we found to handle these events was to give the contractor a choice:

1. Remove the "out of spec" work and start over.

2. Provide independent, qualified & timely written justification (a document with PE seal) stating why the out of spec work is acceptable.

Usually the contractor will choose the the first option, but I have been surprised on occasion when the contractor's "expert" proposed (and we accepted) another way to look at (or solve) the problem.

 

[pmkPE]

If the concrete had not been removed, and for a justifiable price for my time, I would have dowelled into the 10" thick concrete to provide for shear transfer. This would enable you to rest assurred that your top reinforcement is working in conjunction with your bottom reinforcement and that you are in fact getting your full "d" of 17.5".

Shear transfer is VQ/It and "V" is the compression force in the top unpoured slab - may want to use the yield capacity of my top reinforcement bars to determine "V", again depending upon the design and other circumstances.