Concrete Pad Extension

[martin888888]

We have two situations on our site...
1) 5' Wide Concrete Stormwater Trench that we need to extend 50'
2) 8" Concrete Slab that needs to be widened.

Each will need water stops placed, the concrete pad becasue it is in a chemical spill area.

In both cases would it be appropriate to sawcut each to a clean edge and then when extending to use dowels drilled into the existing end with adhesive instead of rebar? With a water stop needed does rebar give a better seal? My main issue is what is better to use, Dowels or Rebar in making a conection such as these. Just curious to hear peoples takes on this

Thanks

 

[JoshPlumSE]

If this wasn't a chemical spill area, then it would be easy. Just use dowels + adhesive. It should be easier, cheaper and less time consuming. Correct me if I'm wrong, but to use re-bar you'd have to chip away enough of the old slab to expose the existing bars so that you can get a good lap splice.

In my mind, the main question is if the adhesive will react poorly with the chemicals. And, I would think the only way to know is to ask the manufacturer about it.

I've used adhesive anchors and such in heavy industrial projects a few times w/o any problems. However, I never did so for an area with direct exposure (like a sump or containment pit). So, I don't know that we looked at the chemical reactivity of the adhesives.

 

[DJSteve]

If there is a concern about the epoxy under chemical attack, consider chipping back concrete far enough to expose a few inches of bar, then install a coupler. Length of bar that needs to be exposed will depend on the size, as the couplers vary in length.

 

[martin888888]

Chemicals will never come in contact with adhesive and the bars. There is a chemical resitant coating on the concrete surface and a waterstop.

Just as you would a dowel cant you just drill into the existing concrete and insert the rebar with adhesive? I beleive the problem with using a dowel and a water stop together is that the dowel allows movement of the slab which you dont want with the waterstop.

 

[SteelPE]

I have never worked on anything that I would be concerned with chemical spills.

However, when doweling one piece of concrete to another I often use the type of dowel recommended by the adhesive mfr. Usually they give load tests data for deformed bars and not smooth dowels. I don't know how you could recommend smooth dowels if you do not have any load tests on them.