Doweling into existing slab
Doweling into existing slab
(OP)
I have a situation where a new slab is going in between two existing ones. There are dowels going into the left hand side, because those slabs will be sharing the same load. My questions are as follows.
1) Does the new slab have to be doweled into the existing slab on the right? Could surface preparation and vertical dowels through that cantilever section be enough? Or does it need shear dowels to connect the two. Intuition tells me it does, or differential settlement will cause that cantilevered piece to break off.
2) If the slab needs to be doweled in on that side I am concerned that the new dowels will hit the existing stirrups. Is there a good way to word how to avoid this on the design drawing? "Dowel every 12 inches, if existing bar is struck move x inches and continue pattern"?
1) Does the new slab have to be doweled into the existing slab on the right? Could surface preparation and vertical dowels through that cantilever section be enough? Or does it need shear dowels to connect the two. Intuition tells me it does, or differential settlement will cause that cantilevered piece to break off.
2) If the slab needs to be doweled in on that side I am concerned that the new dowels will hit the existing stirrups. Is there a good way to word how to avoid this on the design drawing? "Dowel every 12 inches, if existing bar is struck move x inches and continue pattern"?






RE: Doweling into existing slab
RE: Doweling into existing slab
RE: Doweling into existing slab
The reason I am not cutting the existing concrete to vertical is because there is an operational rail on top of it. This addition stretches a fair distance length-wise and I would need to tear up the rail and replace it if I were to do this.
RE: Doweling into existing slab
Will the new slab be the same thickness as this existing slab?
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RE: Doweling into existing slab
RE: Doweling into existing slab
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RE: Doweling into existing slab
RE: Doweling into existing slab
RE: Doweling into existing slab
Suggest getting an experienced geotech involved to design the subgrade. Even then, any needed excavation / backfill will be a challenge to keep from undermining the existing concrete. Predict the slab's settlement and construct with the finish surface "high" by that amount. To make construction somewhat easier, don't try to place the entire 3' thickness in one placement. If calculations permit, use a substantial overlay for the finish surface. We have used this type foundation / overlay approach on the heavily loaded portions of our electric generating stations.
Expansion / isolation joints allow the new concrete to settle without disturbing the existing concrete on either side. Omit the proposed cantilever.
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