have just finished my shed foundation top coat, one cement to four sharp
sand; resting on a base coat of one cement to three sharp and three wickes
how long before i can start walking on it and putting up the tin shed up
please? (in north london its been quite warm last couple of days temps
going around 23 c or so during the day. thanks.
You shouldn't be watching it dry. You should be keeping it wet to
ensure that it continues to gain strength through hydration of the
In the past, hessian sacking was placed over the work and watered
regularly. Nowadays it is more likely to be cured by spraying on a
waterproof membrane and/or covering it with heavy polythene or plastic
Whichever way you choose, keep it wet. It will continue to gain
strength for about 28 days, but will have achieved most of its maximum
strength after 7.
When can you start walking on it?
How long is a piece of string? The longer you wait, the stronger it
will get, provided that you keep it wet. Geddit?
If it was me, I would leave it at least 14 days. But I am far more
patient than you appear.
And have obviously never had to work on a building site. Where you have
to smash the mornings mix out of the mixer cost some bugger didn't wash
it..befire going off for lunch..
In these sorts of temps it will be set enough to walk on in probably
under 8 hours, 24 is reasonable.
Sure it will ge stronger with time, but its strong enough after 24..
On Fri, 8 Aug 2008 17:35:25 +0100, "Andrew Mawson"
They took them away when they took the hessian up.
(The procedure, incidentally, was to leave the concrete exposed
overnight after it had been poured and then to put the hessian down
and spray it the next day. The concrete was cured for seven days
before the road was reopened.)
That's usually the case. ;-)
When people invent something new and highly profitable, they market it
heavily, and often make a fortune. Meanwhile the old methods work
just as well as they always did, and often better than the new.
I recall the claims made for spray-on curing compound, and how its
everyday performance differed greatly from the claims. I only ever
used it with hessian, polythene or flooding the slab with water, never
on its own. Couldn't trust the stuff. ;-)
I felt a warm glow of satisfaction seeing the hessian in use by
Carillion, and even more pleasure at seeing a roll of it on the right
of Peter's very clear picture.
what does 'dust up' mean? PVA it..? Does that mean the PVA waterproof
adhesive I see for sale in Wickes?
Since I don't have any Hessian, would it be a good idea to keep a layer of
old newspapers wet on top of the cement?
Although my original post asked how soon would it be before I could put up
the tin shed on it, I didn't then know anything about keeping the cement
damp for making it strong. It was not made wet for the first 24 hours after
laying it down. For how many more days should I best be keeping it damp? I
much appreciate all the advice I am being given in this group, thanks.
To be honest its been so humid it probably wanst an issue.
The PVA thing is to basically slosh thinned PVA over it - yes the normal
stuff you buy in teh builders merchants. Not sure what it would be sod
as, but its usually siod in 5 liter cans as PVA sealer.
It does two things: stops the cement drying out rapidly and puts a
fairly tough surface on it so it wont wear to dust as you walk all over
it, whne its not completely set (or indeed after,as well)
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