a little cement mishap today

[garager]

hi, i am new to the board. looks like a very nice place!
i hope its ok to ask a question here about cement.

got the garage foundation and some drive poured tuesday - its good to go.
garage floor and rest of drive was to be poured wednseday.
midway through we had a downpour.
needless to say a lot of concrete was ruined.
boss man says he will fix it right and i beleive he will.

most of the garage floor/slab got covered and was saved.
a small part of the slab got to wet and needs to be replaced.
they cut out half of the slab, 12 x 11, and it looks like they want to just pour a new half up against the good half.

my question,
the whole slab should be repoured? or will 2 halfs work ok?

any other thoughts or special concerns that i might should be on the look out for from the water?

thanks for any input!

 

[OH-MAN]

I am not a concrete expert but I would want some rebar in drilled out holes about a foot into the good slabs and sticking into the new pad. This will keep the new one from sinking if the ground settles.

 

[bmwpower]

There will also be a problem with permanent water seepage up through the joint. Will they run a control joint where the two slabs meet or will they simply but the 2 together with no joint? If it's a good looking area for a joint (and doesn't look out of place) I would put a control joint where the 2 slabs meet.

If the ground below where the concrete is to be poured is wet, you will want to wait until it is dry and compactable. Pouring concrete on wet dirt (or wet dirt under wet stones) is asking for trouble. Once the water dries up, the ground will tend to sink somewhat causing the concrete above it to also sink.

As OH-MAN said, at a minimum they will need to secure the new slab to the old one via rebar, otherwise they will shift independently.

Any picts?

 

[garager]

thanx for the comments.
that was my thought - tie the 2 together with bar/dowels although if one sinks wouldnt it drag the other down with it and crack it as it goes down?
the ground is dry so i dont think there will be a problem pouring the new stuff.

 

[bmwpower]

thanx for the comments.
that was my thought - tie the 2 together with bar/dowels although if one sinks wouldnt it drag the other down with it and crack it as it goes down?
the ground is dry so i dont think there will be a problem pouring the new stuff.

That's the idea... You want them to both "sink". Tieing them together will actually prevent one of them from sinking. If they move independently, there will be a difference in height between the two, ie. a lip. You don't want that. You want to try to make them act as if it was one slab. The only way to do this will be to tie the two slabs together.

 

[garager]

just talked to them this morn and they will dowel em together.
thanks for all the comments.
the footings are 12 x 42 and the slab is 6" thick so it shouldnt move a whole lot anyways.

they probably lost 20 yards of cement to the rain.
to their credit they have not hesitated to remove and start over - even some cement that was probably good.
they gambled with the rain and lost - oh well, win some, lose some.
i dont think the loss of profit will affect their attitude.

 

[Wile1Coyote]

Garager Welcome!

Who was it if you don't mind me asking and where are you in Mi? Sounds like some guys I'd like to have do my place, nice to work woth guys who do things right and my driveway is a CLASSIC example of one slab up one slab down as the ****** homeowner before me did it himself.

Only thing I might add is to have them put an extra thich vapor barier in that area to keep the seepage down at that joint.

Thx Jon