Thanks for the replies to my query regarding pouring concrete in cold
Anyhow, this morning I had the concrete poured.
The pump arrived on time, the concrete was half an hour late. The first
thing the readymix driver did was to ask for a cheque or wouldn't provide
the concrete to the pump. I hadn't even got a chance to say hello at this
The readymix had a 125 slump, though an 85 slump had been requested, but the
pump guy assured me this was fine. We poured 5m cubed in about twenty
minutes. I checked the temp of the concrete and discovered it was about as
cold as tap water on a cold winter's morning.
After levelling, I didn't really see the point of the insulating such a cold
mix, but I did so anyway with 25mm polystyrene and some rolls of loft
insulation in plastic sheets. I covered the whole lote with tarp.
Question: will this mix reach a good strength or did I make a mistake in
This would concern me "The readymix had a 125 slump, though an 85 slump had
been requested". You have a lot more water in there than you asked for -
and the more water you have in concrete the weaker it is!
That's why, when you ask a readymix driver to add water to the mix, he gets
you to sign his delivery notes to that effect - to protect his bum if
something goes wrong - like the concrete failing a crush test - did you get
him to sign the delivery note to the effect that HE said the added water
would be OK?
I'm no expert but found this web site for professional yankee pourers last
and Googling for "cold weather curing of concrete" brings back a lot of
stuff. The main thing seems to be to keep it damp for a lot longer if its
cold but eventually there's no loss of strength.
The keeping it damp is to ensure full set, concrete sets by chemical
reaction not by drying out.
I allways damp down fresh concrete each day for first week ...it needs
water to reach optimum set, excess will not arm it after first set has
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