Driveway compaction for slabs - How to get sufficient compaction

[oldtimer]

worried about having sufficient compaction of sand/cement 10:1 bedding layer to take weight of cars in parking space! This is probably not helping lay slabs as vib plate compaction prob too much so finding it hard to get them firm without rocking ! Using standard 2x2 pressed slabs and hoping to use 3mm dry sand joints ? How do I know if sufficient compaction and are sand joints acceptable ? If individ bed how much compaction and what method ?

[carlbeardsmore]

Is it me or is this post very hard to understand?

Every thing you need is on the main site.

Have you read all the site before posting the question?

[Tony McC]

It's not just you Carl - it's like one of those tests we used to get in English class...."Punctuate the following passage of text...."

Anyway, if I'm punctuating correctly, I think OldTimer has laid a cement-bound laying course, then compacted it with the vibrating plate, and is now struggling to consolidate flags when they are laid on top of the already solid laying course material.

Where's he's going wrong is in pre-compacting the laying course. If individual bedding is used, then no pre-compaction is required: the compaction takes place when the flags are individually consolidated with the maul. However, if a screeded bed is being used, then very light partial pre-compaction, just one pass of the plate compactor, would be the best method. This should be sufficient to tighten-up the the bedding, but not to thoroughly consolidate it. Once the flags are laid on it, then the consolidation can be completed by clonking down the flags with a maul.

As for sand joints, I'm not sure these are suitable unless chamfered flags are being used. If these are bog-standard 600x600mm flags, then 10-12mm wide Class II mortar joints should be used.

[oldtimer]

Thanks Tony, was a bit confused about the whole compaction thing and it showed in my post! Have done the occassional patio ok ,but was overly worried about the extra weight of a car and felt the need to try and make a more compact base layer ! Once again many thanks.