C38 slab, how long before i can drill & fix to it

[jotto]

Have finally laid my slab for my parking area, and it didnt rain!

Its C38 I think and varies in depth between 150-300mm.

Its been down for about 24 hours now and seems hard. I have heard some people say if I put rawl bolt type fixings in now it will be easier to drill but others have said to let it go off for around 28 days before working it.

I have a HD drill so thats not an issue, just dont want to cause any damage or have weak fixings.

TIA.

[seanandruby]

Why the variation in depth? surely it would of been cheaper and less work to use a sub base to make it all the same depth?
48 hours should be ok.

[Tony McC]

It's not so much the drilling as the fixings that are a potential for problems. Drilling doesn't place much stress on a slab, but inserting an anchor bolt and then tensioning it does, as the anchor is held in place by the pressure it exerts on the surrounding material, namely the fresh concrete.

So, while drilling would be ok after, say, 48 hours, I'd want to wait at least 5 days before putting any tension on the anchor bolts, and ideally, I'd leave it as long as possible.