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#11530 - 08/02/07 08:49 PM Cure Time

I live in Northern New Jersey and poured about 4 yard of cement to replace a sidewalk and driveway apron. It was about 90 degrees, high humidity and mostly in the sun. My uncle is a contractor and has done a considerable amount of concrete work during his 50 plus years in construction.

We ordered extra retarder in the mix to make sure we had plenty of time for finishing. The entire work area was completely wet down - forms, joints and underlying gravel. We asked for a loose mix, the driver poured, and left.

Within 1 hour, the concrete began to harden and was all but unworkable within an hour and a half. When we tried to take the forms out to insert to expansion joints, we could not. The concrete chipped in large chunks and cracked. We were able to walk on the concrete within 2 hours with no footprints at all. The crackers looked as if concrete was pulverized, it looks as if a powder was dumped in the cracks.

We called the cement company and after some kid looked at it and said they will supply a new batch of cement. We said they should tear up all the bad cement as well. The kid called the owner and came back and said, "Take us to court." When we called today to try to resolve the issue, they told us to stop harrassing them or they would call the cops.

What would cause the concrete to harden so fast? Could this have been left over from another delivery earlier in the morning? Was there something that we could have done to cause this to harden so fast?

#11531 - 08/02/07 11:20 PM Re: Cure Time [Re: ]
CR2 Offline

Registered: 01/09/07
Posts: 498
Loc: New York
Unfortunately, it looks like you could not handle those 4 yards,it was a good idea to add the retarder, but you really needed more manpower, at 90 degrees concrete goes quick,really quick; retarders give you a 30 to 90 minutes window(since they are added to the mixer),counting driving time (30 min) and placing time(30 min) your window is almost gone(best case scenario 30 min left to start the non stop finishing process).
Regarding the removal of the forms to install expansion joints, not a good idea either, prep work should be done ahead of time, all expansion joints,rebar,control joints marks...needed to be done with plenty of time, before concrete arrived.
My best piece of advise is to do the removal yourself and to get the free concrete offered by the supplier,it will very hard to prove that their concrete was wrong and you did everything right, usually concrete is right and placing and finishing techniques are the key for a good final product, I think you have no legal ground to win the case, but I'm not a lawyer and if you feel different about this issue, contact an attorney for help.
Good Luck!