Is it possible to pour concrete in two steps?

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Above our garage, a lintel 7 meters long and 1 meter high was formed and poured. Now the builders must have miscalculated the amount of concrete. This means that the concrete is still missing about 1m long and about 20cm deep. This will definitely be poured today. Now the question. Since the concrete that has already been poured has dried out before today, is it possible that the concrete that will be added today will not "bond" with the concrete that has already been poured? I would like to know if there are any problems with load-bearing capacity, deflection and strength? Or is none of that a problem. 




Brush / pre-fill hardened concrete with an aqueous cement solution (no sand), this will improve adhesion to the fresh concrete. Loads must be taken mainly by the reinforcement.


What do you think they do on big construction sites, it's not like they concreted the foundation in one day, if the rest is done today, I don't see a problem.


I don't think it's that unproblematic. Okay, the lintel holds the concrete, but the old/new bond will not. So I would worry about water infiltration and possible further separation of the concrete pieces.

I would definitely point out this defect to the construction manager.

It is unfathomable to me that they miscalculated the concrete in such obvious quantities.

  • I would tell a structural engineer about it with pictures. And if you fill in the concrete later, moisture can get into the contact area.  
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