Concrete slab curing question
Discussion
jagracer said:
I laid a 16'X 9' concrete slab for a shed in my garden and wondered how long I need to keep it covered. The temp was down to minus 4 last night but hopefully it'll be warmer tonight and over the weekend with daytime temps up to around 10c.
I'm sorry but your slab is going to crumble with frost damage unless you happened to put at least T50 macalloy reinforcing bars in it.Not to mention the threat of cracking from contraction/expansion if you didn't put a expansion joint in the slab.
Did you check the amount of pozzolanic material in the mix ?
sleep envy said:
Swilly said:
sleep envy said:
Swilly said:
I'm sorry but your slab is going to crumble with frost damage unless you happened to put at least T50 macalloy reinforcing bars in it.
concrete spalls from frost without re-bar?
It's massively over the top... hence instead of a sensible answer, i gave a similarly over the top answer

Let me give you guys a tip on shed bases which will save you a few quid.
I dont know why people use concrete for a shed base.
Usually it will be about 2-4" deep with no re bar and some dodgy inconsistent mix when done by an amateur (or some pros for that matter)
To do concrete properly its actually quite expensive what what is esentially a hidden base for a shed.
Imo best thing to do which if done properly will last a long time
600x900 council slabs laid on compacted sharp sand (50mm) (you could even tread the sand in) on a decent (4" thick) sub base which is properly compacted.
Much quicker,cheaper and if done properly will last a long time.
You will need access to a wacker plate and those 600x900 council slabs are heavy as a muthaf
ker !
I dont know why people use concrete for a shed base.
Usually it will be about 2-4" deep with no re bar and some dodgy inconsistent mix when done by an amateur (or some pros for that matter)
To do concrete properly its actually quite expensive what what is esentially a hidden base for a shed.
Imo best thing to do which if done properly will last a long time
600x900 council slabs laid on compacted sharp sand (50mm) (you could even tread the sand in) on a decent (4" thick) sub base which is properly compacted.
Much quicker,cheaper and if done properly will last a long time.
You will need access to a wacker plate and those 600x900 council slabs are heavy as a muthaf

This was built by Morrison,s in zub zero temps. & seems to be OK.
http://en.wikipedia.org/wiki/Cairngorm_Mountain_Ra...
Loads of poured concrete and steel.
HTH
http://en.wikipedia.org/wiki/Cairngorm_Mountain_Ra...
Loads of poured concrete and steel.
HTH
Swilly said:
jagracer said:
I laid a 16'X 9' concrete slab for a shed in my garden and wondered how long I need to keep it covered. The temp was down to minus 4 last night but hopefully it'll be warmer tonight and over the weekend with daytime temps up to around 10c.
I'm sorry but your slab is going to crumble with frost damage unless you happened to put at least T50 macalloy reinforcing bars in it.Not to mention the threat of cracking from contraction/expansion if you didn't put a expansion joint in the slab.
Did you check the amount of pozzolanic material in the mix ?
pimpin gimp said:
shouldn't really be laying concrete in temps as cold as that, you might get lucky with it being covered, but it wants a good half inch of foam type material over it to keep it safe on cold evenings...
I didn't lay it in sub zero temps, it was around 10 degrees yesterday, it got cold overnight which was after I laid it. Edited by jagracer on Friday 6th March 22:30
m3jappa said:
Let me give you guys a tip on shed bases which will save you a few quid.
I dont know why people use concrete for a shed base.
Usually it will be about 2-4" deep with no re bar and some dodgy inconsistent mix when done by an amateur (or some pros for that matter)
To do concrete properly its actually quite expensive what what is esentially a hidden base for a shed.
We always use concrete for shed bases, much better than any paving slab rubbish, you get a nice hard solid floor which is a benefit and they stay where you put them and it will last for the life of multiple sheds, but then our shed is better built than timber framed houses are nowadays.I dont know why people use concrete for a shed base.
Usually it will be about 2-4" deep with no re bar and some dodgy inconsistent mix when done by an amateur (or some pros for that matter)
To do concrete properly its actually quite expensive what what is esentially a hidden base for a shed.
You can pour concrete in whatever temprature you like as long as you can ensure that the water doesn't freeze during the initial set and curing period, as we all know water expands when freezing thus damaging the internal structure of the concrete.
If you can get hold of the winter concreting advice by a chap called pink its well worth reading. Wind chill is also something to take account of.
If you can get hold of the winter concreting advice by a chap called pink its well worth reading. Wind chill is also something to take account of.
Edited by ALawson on Saturday 7th March 09:56
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