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RE: time before building on or backfilling concrete foundation walls

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I didn't think so but I was hoping ... since I am in UBC territory I
rarely look in the ACI anymore (I knew the 89 version like the back of
my hand, but I have opened my 95 ACI maybe 10 times), but that will
change when CA decides to go IBC. Thank you for confirming this Scott.

The only alternative that I can see is to evaluate the strength of the
concrete with samples at whenever the contractor wants to start
backfilling or working on the concrete. Then, construction loads need to
be evaluated with respect to the strength of concrete ... seems that it
would lead to abuse by the contractor who has their onsite "engineer"
determine the adequacy of loading the concrete...

This is a common request from contractors who don't know what they are
doing... if they knew what they were doing and they would have known the
schedule was tight they would have used high-early concrete - cast on a
Friday morning and ready to be worked on Monday or Tuesday morning.
These guys always want to backfill 2 days after "pouring".

-gerard
Santa Clara, CA 

-----Original Message-----
From: Scott Maxwell [mailto:smaxwell(--nospam--at)engin.umich.edu] 
Sent: Thursday, August 15, 2002 10:41 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: time before building on or backfilling concrete foundation
walls

Gerard,

I don't believe that ACI 318 has anything on this.  I looked through
quickly to be "sure" and did not find anything.

Scott,

This would typically be a judgement call by the engineer of record (kind
of ironic considering the other thread out there about judgement
<grin>).
Gerard's answer is consistant with what I have seen/used in the past.  I
am used to specifying that the concrete must obtain 75% of the 28 day
strength, which will typically occur fairly close to the 7 day point.

HTH,

Scott
Ypsilanti, MI


On Thu, 15 Aug 2002, Gerard Madden, PE wrote:

> Scott,
> 
> Typically it is 7 days after casting unless high-early strength
concrete
> is utilized. Compressive strength is about 65% of 28 day strength (if
I
> remember from concrete class-10 years ago) at 7 days. This should be a
> typical note in the general notes of any project. Not sure if this is
in
> the code, but ACI may have it in their ACU 318.
> 
> -gerard
> 
> -----Original Message-----
> From: Haan, Scott M. [mailto:HaanSM(--nospam--at)ci.anchorage.ak.us] 
> Sent: Thursday, August 15, 2002 4:18 PM
> To: Seaint list (E-mail)
> Subject: time before building on or backfilling concrete foundation
> walls
> 
> Are there any rules of thumb about time limits on when it is
acceptable
> to
> start building on a concrete foundation walls and footings?  It seems
> you
> would not want to backfill a basement wall or retaining wall until the
> design strength is reached but I cannot find a code reference and
> wondered
> if there is any guidance published on the subject.  
> 
> Thanks.
> 
> Scott M Haan P.E.
> Plan Review Engineer
> Building Safety Division 
> Development Services Department
> Municipality of Anchorage
> http://www.muni.org/building
> phone:907-343-8183  
> fax:907-249-7399
> mailto:haansm(--nospam--at)ci.anchorage.ak.us
> 
> 
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