By "control joints" do you mean expansion joints?
Can you elaborate more on both? Perhaps more toward pouring a shop floor on
foundation earth.
--
Mr. P.V.'d
formerly Droll Troll
"Rudy" wrote in message
news:NOr5g.103608$P01.24114@pd7tw3no...
going to have a new driveway poured. One of the contractors [with the
best price] said we didn't need rebar because the concrete he used has
the fiber in it. Should I insist on rebar or does the fiber negate the
need for rebar?

Thats why he had the best price..the least work. For a smaller slab like a
patio, for foot traffic, I'd go with fiber. Our patio slab has rebar in
it because a 3000 lb hot tub is going to be set on it soon. For a driveway
which has to bear the weight of vehicles, I'd use rebar, 1/2" dia. spaced
2 feet apart and wire tied at least every second "+". We did ours a last
June and I did all the prep work: levelled the soil, spread 2-4" gravel
(to get the slope right) and used a rented compactor over it all. Then
went with 1/2" rebar, 24" OC. The China building syndrome has driven the
price of nearly every building material up and rebar is no different. I
got a deal on 20' (6 meter) lengths @ $ 4.00 Used 80 pieces. I see it
for $ 5.00 now
We went with ~10 yards of 3500 lb concrete, 4" thick (not the 3.5" of a
2X4). After we did the "plain" concrete ~ 45' X 17', I stripped & moved
my side forms "out" 18" and re set them, then dropped two rows of rebar
in, crosstied every 4' and poured an 18" wide accent strip that was
ordered in 'exposed aggregate' down each side of the original DW. Also
did an exposed sidewalk up to the house/steps which were 'ag' also. I
recently drove our 12,000 lb RV and 7500 lb pickup over the exposed 'edge'
for the first time and no cracks. BTW, this driveway incorporates a 90 o
curve so the forms were 2 layers of 3/8" plywood with plenty of stakes.

I should add that many concrete 'experts' say that all concrete will crack
and that the rebar just holds it together. On a driveway, the control
joints may or may not crack..depends on how good the prep work was IMO

R

PS, make sure the rebar is supported before/during the pour. It needs to
be "in" the slab, not laying on the ground. Watch the whole process
carefully and you can do your own small jobs like sidewalks and slabs next
time...Its not rocket science. If you're going to give it a try, start
small.