Hi,
I have a 1m trench at the rear or my house ready for some concrete to be pumped in later in the week (about 5m cubed). The readymix people and the pump people said the weather isn't so cold that I should put it off. But I'm not so sure. I'm in the East Midlands and the daytime temps are set to be about 2 degrees. Any advice would be appreciated.
TIA. bhads.
Should be absolutely fine, if you want to make sure of it then cover it up for a few days with a cheap "tarpaulin" (the sort with eyes around, made of green plastic) from Wickes or wherever.
Never mind what the daytime temp will be, what is the lowest temp (ie night-time?) likely to be, on the day of pouring and several days afterwards?
IANAE but I certainly think you're right to be cautious about doing this at the moment. I know there are various anti-freeze type additives you can include in the concrete mix; maybe the readimix folk are doing that, and maybe that's fine; I wouldn't know.
David
If it is going below freezing a layer of straw then a tarp will do the job. If it is only dropping below freezing after dark ... then try and get it poured as early as possible ... so it starts to go off before you have to straw & cover.
The concrete "in the ground" will be fine unless it gets very cold, it just the top few inches you need to worry about. Once its been levelle you should spread a good layer ( say 4") of straw over the top t insulate it and keep the frost off, if you can cover that with tarps o plastic sheeting all the better. The concrete generates a lot of heat a it cures and so will naturally protect itself from frost, its th surface where the damage is done
-- Nick H
Thanks for the replies to my query regarding pouring concrete in cold weather. 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 point. 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 accepting it?
TIA Bhadan.
It'll be fine. Ive worked on many jobs where, beacause of limite access the concrete has been poured at one corner of a foundatio trench. In order to get the stuff to flow as far as possible th readymix has been specified with a high slump and sometimes more wate was added on site. Strictly speaking you shouldn't add water after th initial mix but i've seen it done many times and the concrete stil went off ok and the houses are still standing 25 years later
-- Nick H
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