Rocky slabs?!

[matthewlancs]

Hi guys,

I have just laid half of my patio (natural sandstone) onto a base of 4:1 grit sand and cement "dry" mix using the screeding method.

The patio has had a week or so to go off and probably around 30% of the slabs seem to have fixed in place. However, the rest of them have a slight rock to them when I walk over them and there are a couple that are rocking significantly despite being laid on a very level screed mix which was in turn on a decent sub base of well compacted crusher run.

I intend to use a resin based grout in between the slabs and am wondering if I need to re-start the patio at this point and switch to a wet mix or whether I'd be ok with this slight rocking in terms of the resin mix holding it sturdy?

Any thoughts would be great!

[local patios and driveway]

Did you use a bond? I think i can see the problem here, when laying on a semi dry screed you need a bridging bond between the screed and the mix, this is usually an sbr cement and water mix. I dont pull and punches and I think you just made a big mistake... Lots of work ahead

[matthewlancs]

No, just laid onto the dry mix directly......listened to the advice of a friend.....never again....lol

Not laid much of the patio so contemplating just taking the mix up and re-laying onto a wet mortar bed - do you think this would be best?

[r896neo]

yea get it up now. the sooner the better as the mortar will only get harder.

Look on the bright side at least they will be easy to lift.

[rimexboy]

I did a very similar thing I used a wet mix but not wet enough, also I was told to wet the back of the slabs a bit so they don't suck up to much,

It was also also sandstone.

Pull the bit you have done up and have another go, you will be much happier with it in the long run

[local patios and driveway]

Have it all up while ots still green concrete, break ot up and put it over your sub base so its not wasted, compact again and then read this site on how to do it right, secondly, tell your mate he is a first class idiot who probably guesses at answers so people think he knows what he is talking about..... He dont

[matthewlancs]

2 days hard graft and the ground is back to compacted base!

time to get the wet mix mixing i think!!!

[rimexboy]

Yer not nice on the back but you live and learn like me the hard way lol