Can cold weather damage my concrete?


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Old 01-08-21, 06:48 PM
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Can cold weather damage my concrete?

I make DIY concrete weights so i can work out at home due to the lock downs.
Now i usually make the weights, let it dry for 3 days. Then put it outside to dry some more, once i remove them from the mold. The bottom is always still a bit dark grey/wet. However once they're outside for a day, it hardens just fine.

My question is: Can cold weather damage my concrete weights? They're already solid after 3 days, however they're just not 100% completely dry yet when i remove them from the mold (since they turn white when they do).
The weather where i live is around freezing point. So 32 F or 0 degrees celcius.

Will this damage the concrete weights? will they crack if the little bit of remaining water in the mostly dry weights, freeze and expand? Or will it be fine since they've already solidified? The package says concrete dries in 48 hours and they've been inside the mold for 72 hours, but i guess some moisture always stays trapped at the bottom.

Thank you very much for reading.
 
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Old 01-08-21, 07:13 PM
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Yes, freezing weather can definitely ruin or at least weaken concrete. Ice expands, so as long as your concrete still contains water, freezing temperatures will damage it. If its something you can't move inside then it helps to cover it with anything available. Blankets, hay, straw, insulation, tarps, etc. The heat from the ground (assuming the ground isn't frozen yet) will typically help keep it above freezing if you can keep the wind off it. Concrete doesn't reach full cure (90% or so) for 28 days. So you don't really want it to freeze for at least 7-10 days for best results. Additives can be added when working in cold temps below freezing. Maybe you could look into that if your work needs to continue into winter.

Better yet, move them anywhere inside where it won't freeze.
 
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Old 01-09-21, 04:52 AM
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I agree, freezing is bad for concrete. Concrete cures, it doesn't dry. In fact drying is bad for the strength of the concrete. The chemical bonds that make concrete strong occur in the presence of water. No water and the concrete stops curing and getting stronger. Most concretes are not considered at full strength until 28 days and if you keep it damp for that time you'll get maximum strength. You do not want the concrete to freeze during that time as the expanding ice crystals can damage/weaken the concrete.
 
 

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