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RE: Concrete Cure Time

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Thanks for everyone’s input on this one.  As far as I know the 3 day rule has just been something of a rule of thumb in this area.  It appears to me that even at an early stage concrete will have enough strength to sustain a day or so worth of hollow block work – that’s not really all that much pressure.  I’m going to suggest that we allow the placement at 24 hours, but not allow the cells to be poured until a yet to be determined time frame. 


Again, thanks.





From: Jim Getaz [mailto:jgetaz(--nospam--at)]
Sent: Wednesday, September 02, 2009 7:23 AM
To: seaint(--nospam--at)
Subject: Re: Concrete Cure Time



                I concur with Harold and Jordan. We transfer prestress at 12-16 hours, depending on how long the crew worked the day before. Our minimum is 3,500 psi, and can be as high as 4,200 psi with our normal mix. We break two cylinders (three, soon, I guess) for a full test before cutting strand. We used to use high-early, but cannot purchase it anymore. I doubt our normal mix would resemble the average slab-on-grade normal mix other than rocks, water and cement, but let them prove they can proceed. This is not your call.

        Jim Getaz

        Precast Concrete Engineer