On 11/2/2013 3:27 AM, David Gilbert wrote:
That (heat) is not why you should keep the concrete moist. Concrete is
a hydraulic cure, meaning it requires water to cure. If concrete is
allowed to prematurely dry out it doesn't become strong until it gets
wet again, and may not ever reach the strength it would have if it had
remained wet. A bit of surface water will do almost nothing to affect
the internal heat generated by curing, but it will greatly facilitate
the cure itself.
By the way, too much water in the mix is not a good thing either,
because after the cure is complete the excess water will eventually
depart leaving small interstitial spaces ... and air is very poor in
compression. ;) The strongest concrete is that which just barely has
enough water throughout the curing cycle to complete the chemical
reaction. That is rarely seen in practice, though, because such a mix
would be very stiff and hard to work ... certainly difficult to pour.
My garage and shop aprons are excellent examples of that. It was one of
the hottest days of summer. They put extra water in the mix to keep it
from drying out. No amount of watering would fix that. It looked great,
but after the first winter's, surface freeze and thaws the surface
spalled off. The contractor said it was due to the salt because the
pattern followed the tires (loosely), but that was just hydraulic
pressure forcing water into the voids. I eventually cleaned it and gave
it 3 coats of epoxy, but the concrete under that eventually came loose too.
73,
Roger (K8RI)
73,
Dave AB7E
On 11/1/2013 12:20 PM, Tom Anderson wrote:
Doug:
One thing you might do is what I was told when I put in my base
back in 1993. Lightly water the concrete base daily. I mean
lightly, no gushers, etc. Just a sprinkle for a couple minutes.
This helps take out the heat from the curing concrete. I mnust have
worked because my 4x4x6 ft base is still in fine shape as when I put
it in.
Tom, WW5L
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