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

BobK207

wrote:
"BobK207" wrote in message
oups.com...

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

Spalling on bridge trusses, coated beams, etc, is a very big problem here in
SW Michigan. I know several 40 year old bridges where they had to replace or
cast over and make thicker the pillars, and parge the supporting beams. All
recent projects around here are designed with coated steel and replaceable
decks instead of concrete over steel. Sure, there is still concrete in them,
but they are designed so the salty crud doesn't saturate the concrete and
rot the rebar. A couple historic bridges had to be torn down, due to the
left-in-place steel forms under the concrete arches rotting out.

Didn't somebody develop rust-resistant rebar a few years back? Special
alloy, some sort of coating, and some sort of field prep kit for welded and
twisted joints?

aem sends...

Didn't somebody develop rust-resistant rebar a few years back? Special
alloy, some sort of coating, and some sort of field prep kit for welded
and
twisted joints?

Epoxy coated rebar but the coating is easily damaged during placement
care must be taken

Stainless steel rebar does exist but the cost is high.

cheers
Bob