DIYbanter - View Single Post - how to make sure that driveway does not crack

BobK207

pe wrote:
On Sun, 07 Jan 2007 23:30:41 GMT, "George E. Cawthon"
wrote:

wrote:
On Sun, 7 Jan 2007 13:10:56 -0600, "Steve Barker"
wrote:

Rebar, lots and lots of rebar. And concrete 6" thick. Did i mention rebar?

Except lots of rebar can also mean lots of spalling. Rust requires more room than
steel and can explode the concrete.

I think you are joking. If not, the rebar should
be in the lower third of layer. How do you
explain the lack of spalling on exposed concrete

Do a little net search.
Spalling is an IMMENSE problem in concrete structures.

pillars, e.g., bridge supports, basement supports,
etc. since they have lots of rebar.

They generally know what they are doing.

In Quebec recently an overpass collapsed killing people. Spalling is the probable
cause.

Spalling in concrete on the ground can be very bad due to the moisture. There is such
a thing as TOO much rebar.

Do a little net search.
Spalling is an IMMENSE problem in concrete structures.

Rebar corrosion....one of the causes of spalling

is strongly dependent on the thickness of the cover (amount of concrete
over the rebar), soundness of the concrete & the local environment.

a marine environment is probably one of the worst as is one where snow
removal chemicals are used

general cover suggestions

air 2"
soil 3"
marine environment a lot more

another cause of spalling is freeze thaw but I doubt we're concerned
with this on the OP's driveway

plus to add "too much rebar" to a slab it would have to be quite a
bit....I'm sure the OP's driveway project will get less than minimum
temperature (if it get's any)

btw I'd wait until some investigation work has been done before
suggesting a reason for the Quebec overpass collapse you mention.

This isn't the first collapse.

cheers
Bob