was laying some concrete yesterday, looks good, but i ran out of stones. now the layer i did yesterday should be fairly dry by now although it did rain last night which i didn't expect...

am i going to come across problems pouring another layer on top today, on top of an already dry layer?

heavy rain is forcast about now too.... lol its 25 degrees outside. is it a bad idea to think about doing more? am i wasting my time thinking about it? its only a small area, so easily covered til another day if i have to


its supposed to be the same level as the shed base

[Edited on 2/7/09 by blakep82]

Concrete shouldn't 'dry' it should 'cure'.
You need to keep the curing concrete moist (cover with damp hessian sacks.
If it has 'dried' then the second pour may not take.
Perhaps you could use a PVA bonding agent but I'm no expert!

Score some marks across the surface, to help the next layer to key in.

Cover it with wet sacks or cloth to stop it drying out too fast (goes brittle) especially in this heat.

Cover with polythene to stop the rain from washing off the cement layer and leaving you with a crappy surface (all stones exposed and nothing to hold them down)
As you said its going to rain.

You could put a layer of wire mesh (from garden centre) to reinforce the thinner top layer when you pour the next part of the slab.

Or... lay paving slabs on top, with a lean mix bedding. (easiset I would think)

PS... I work in electronics, and am not a builder. Its just a few years of home improvements speaking!

When they concreted my yard two weeks ago ( 4 lorry loads and 6 inces deep) they where praying for rain otherwise they had to keep it wet with hoses. I think if the concrete dry too fast witch it will with this kind of heat, then the concrete will crack.
I am not sure if you can poor another load of concrete to another allready set one with out ending up with two blocks of concrete???

well, withe the rain last night, i don't thnk its completely cured. maybe i'll just go for it. nothing to lose lol i'll ask at the builders yard if it should be ok to pour on top again

It would have been better to do it all in one layer rather than another thin layer on top but if it's not a heavy traffic area you should be o.k. Concrete sets by a reaction which needs water and generates it's own heat so cover it with a sheet of plastic and leave it overnight. It takes a couple of weeks to gain full strength.

the guy at the yard said it should be fine, so i'm going to crack on with the next bit. its about 3" it needs on top, so not too thin

just wet the concrete before pouring the next, it'll take

my garage floor was poured just before a torential downpour and it did the surface a world of good gave me a very nice clean smooth but slighty dimpled texture while washing all the scum away

as said above concrete cures not dries a rough rule of thumb is at 25mm a day ..... and with respect yours is only carrying a shed

As said before it will take weeks for the concrete to cure to an acceptable stage and can take months to fully cure depending on a number of factors.

Im not sure if your thinking of any sort of finishing i.e. paint or resin but it should be left a couple of months before you do it

for a finish, i was just going to leave it a bit short of the top and then screed over the top.

i know its only carrying a shed (well, its a step to the shed...) but its been needing done for a while, my mum and dad are going away for a few days and i wanted to get it done for them coming back. not told my dad i was doing it for him, so i didn't want it to be a disaster and fall apart

Anorak alert.

Concrete "hydrates"...

it does what now?
lol

whats the deal with this severe weather warning?! it said we'd have 8mm between 1pm and 4pm, and 9mm between 4 and 7. there's been nothing at all so far!

thats because concreting is a science where weather forcasting is just guess work