I had a new concrete driveway poured about 5 days ago . I waited 24
hours then have been misting it with a hose 3 times a day ( except
for rain of course ) . The weather has been overcast more or less and
the temps have been ranging for 50-68 degrees F. How long should I
wait before drive on it with a full size pickup truck ( unloaded ) . I
want to use the driveway ASAP but don't want to take any unessary risk
About 25 years ago, we blasted a flat spot into some solid granite
on a lot near Burnet, TX. and set up forms for a driveway with great
difficulty. We used #4 rebar in a grid pattern, 16" OC each way.
Poured 5,000 PSI concrete 5" thick. Waited 5 days and drove large
trucks over it with no problems.
Had a neighbor that poured 3,000 PSI concrete 3" thick with WW
mesh. Wet it down for a week after the pour. He did NO surface
prep, didn't even remove the carpet grass under the slab. Cracked
the first time he drove on it with his Geo metro.
Wait at least a week, but as long as you can after that, up to 14
days. You should be able to drive on it in a week. I just like to
hold off until I really need to get on it.
We have driven on driveways after 3 days with no problems, but I
would not recommend it.
Concrete cures to it's full hardness in 28 days assuming proper
conditions (temp., proper watering, etc).
Are you sure they were letting it sit for a year just to cure? Or
were they still working on it?
On 22 Nov 2004 13:52:10 -0800, firstname.lastname@example.org (Al Bundy) wrote:
Are you sure you don't mean nominal hardness? I thought that
concrete normally kept hardening for years, asymptopically
approaching some ultimate value, and that the 28-days was just
the standard to which they test the stuff.. So that 5000psi concrete
is called that because it hardens to 5000psi in 28 days...
That is correct. With most types of concrete, it cures to its rated
capacity in 28 days. It will continue to cure for about 100 years,
according to the experts. Some types are different (high-early
comes to mind, but for the most part, 28 days is the norm.
A crack would be the usual sign...
Doubt a little Toy is going to damage a slab that has been curing for 5 days.
Might be a bit concerned if the delivery truck pulled onto the slab with a full
load of shingles, but a bitty pickup? Nah....
thanks all for allaying some of my fear..
came out this morning to check on it-definite permanent tire marks on
where the truck was moving. It's been raining and cold (SF bay area) so
I'm concerned the concrete didn't have time to set. Didn't see any
cracks but where could it crack? I mean it's a 20x50 ft driveway; it's
not a sidewalk.
Tire marks? As in "impressions in the concrete", as opposed to "black marks
from the tires"? Seems pretty unlikely after five days of cure time. Rain
shouldn't cause a problem (concrete *likes* "wet" when curing), and, IIRC,
"cold" in the Bay Area is still usually above 40F.
As to the "where" of cracking, a properly designed slab will first crack along
the joints (as designed). No contractor worth beans is going to pour a 20x50
slab without a few joints in there. Over time, you'll get cracking along other
parts of the slab (take a look at pretty much any >10 year old residential
Bruises, broken arm, bullet holes. Oh, you mean the slab.
If you don't see any obvious damage, then damage is
unlikely. 5 days curing in temperatures above 40 will
support a small truck just fine. Heck, two days at higher
temps would probably be ok.
Too late now but your best bet for a good cure was to water it heavily
and the cover with plastic so it would stay moist constantly. After 5
days it isn't going to much harder. If you really need to drive on
it, then put down sheets of 3/4" plywood to spread the load. 3/4"
plywood will protect lawn from an empty pickup.
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