Re: Why Put gravel under concrete?

On May 6, 8:43�am, mister_frien...@the-newzgroups.com wrote:
> I have poured many small sidewalks and shed floors and never put
> gravel under the concrete. �I want to pour a driveway section in front
> of the garage and was told by a guy at the concrete company (who came
> to measure the amount needed), that I need to put gravel under the
> concrete. �WHY?
>
> I should mention that I always put lots of small to medium sized rocks
> under concrete to save on the amount of concrete needed. �I save all
> rocks I get just for that use, and leave them get rained on to clean
> them. �Any rock that will not exceed the height of the forms, goes in
> there. �Because this will be driven on, I intend to put in some rebar,
> which I never do on sidewalks and shed floors. �I have never had any
> problems with these sidewalks cracking or substantially lifting in
> winter.

It helps to drain away any water that may accumulate. In cold climates
this can cause frost heave.