Laying a concrete slab on wet ground

[David WE Roberts]

The snow is eventually clearing and the forecast has suggestions of days above 4C.

So I may be back in the concrete laying business after a forced layoff.

The ground, however, is going to be pretty soggy and there is a lot more rain forecast.

My next step is to lay 100mm of MOT, whack it down, and put up the shuttering.

The ground is fairly light (thankfully not clay).

So is there any reason not to crack on?

I can't see one immediately but thought I would check with the NG just in case.

Cheers

Dave R

[The Natural Philosopher]

No.

I've not found whacking to be particularly good at compacting MOT mind you, Consider rebar in the slab to prevent cracking.

[Tim W]

David WE Roberts wibbled on Saturday 16 January 2010 08:56

If when you whack the MOT, you end up sitting in a pool of water, it is probably too wet.

If it whacks down hard and doesn't do that, then the water is probably helping, but allowing what's under the MOT to compact properly too.

Clay's probably the biggest pain - if it's sopping wet, it tends to slurrify and push it's way into the hardcore (never used MOT, but regular rocky stuff does this) and you never get the feeling that the hardcore is doing anything but floating around on a wet layer of s**te, which will then shrink later when it dries.

Got some frost protection ready for the concrete (additive or suitable covering while it's going off)?