Drying time

[john simpson]

What's the general setting time for dry screed?
48 hours and still spongey.
Was 70mm with the odd bit deeper and a few spots shy.
Black plastic and insulation, only odd thing was light polythene type plastic over all that, then the screed on top.
House was damp at one time as work is dpc but air feels dry, locked up so no real circulation.
Should I be worried or leave it for the weekend?
Any ideas why it is not dry enough to walk on?

 

[malc]

what was the mix of your screed?
you should be able to walk on the screed next day.
flood the screed, cover with light poly, place a few bricks to keep it in place . so that the screed can cure. when you use semi dry mix the cement has not got full strength. you should do this every day for 7 days for a class B screed.

 

[john simpson]

Was ready mix so no idea but would of been standard.
I haven't seen it so don't know how soft it is but he's saying he can't stand on it.
Was packed down and the stuff was standard , was going off after a few hours.
Just the usual, I haven't done one in years but never had this problem before.
Can't understand why it's still soft unless an issue with the mix.
Would you get the supplier out to take a sample?

 

[Natwasere]

If it's delivered there can sometimes be a r******d in it, but 48hours it should be firming up by now

 

[gps]

whenever I've done screed its always been a next day walk on, but its been a few years since I've done one also

 

[john simpson]

OK thanks folks.
Maybe a retarder in it, hopefully it's dry tomorrow.
At least I got a new float broke in

 

[gps]

on the bright side it was ready mixed so not your problem anyway

 

[malc]

with retarder it will stay soft for a couple of days. it will still require curing.

 

[stokeplasterer]

For every millimetre of screed it's one day dry time , so for 65mm = 65 days
But as you know if you are careful you can walk on it the next day