How should rebar be placed in a concrete driveway?

Question

I've been getting bids for a concrete driveway roughly 9' wide by 200' long. There is a wide variation in what what each contractor is proposing for the rebar-

3 lengths of rebar running the length of the driveway with horizontal bars every 6 feet.

4 lengths of rebar running the length of the driveway with no horizontal bars across the width of the driveway.

2 lengths of rebar running the length of the driveway with horizontal bars every 8 feet.

I'd have thought there would be more consistency. Can anyone recommend the best pattern for rebar for a driveway? Does it need to be run horizontally and vertically in a grid, and if so, what horizontal and vertical spacing?

Answer 1

A lot depends on how much weight your going to be putting on the driveway. With a good sound base you should be able to have 3 #4 rebar run the length with horizontal bars every 3 foot. There are recommendations for rebar to be on 12 inch centers. There are also better materials to use than rebar. See this web page.

http://www.wikihow.com/Build-a-Concrete-Driveway.r

Answer 2

Driveway Rebar Spacing

Answer 3

I don't know why rebar is being used in this case. In a driveway 5" -6" thick, normally a reinforcing mesh ( welded wire fabric ) is used. All reinforcings need to be in the slab, not beneath it. When pouring with mesh, it is pulled up into the middle of the concrete. With rebar, it is normally set up on "legs" which pre-places it in the concrete. You see rebar in flat slabs normally thicker than a standard driveway; such as a roadway or garage floor which would hold heavy equipment.

The mesh or rebar needs to be tied together when overlapped. Mesh or rebar does not prevent cracking, it helps to minimize cracks and holds the slab together when it inevitibably does crack. Installation of expansion and control joints is every bit as important as the reinforcing in crack control. If I am correct that your driveway will be no thicker than I mentioned, rebar may actually cause more cracking as it will eventually rust which will cause it to swell.