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Posted: Fri Mar 30, 2007 12:07 pm
by novicejohn
Proving that i am still a novice i have started setting out a 9sqm segment (1/4 circle) of block paving and have a problem with the 'exposed' edge. I am overlaying the blocks on an existing concrete base.The 2 sides that form the 90 degree angle (3m lengths) i have layed with soldier edges and haunched them in channels between the paving and the house walls (due to low dpc), in a corner.

The outer curved edge is a 'free edge' and this will finish as a 'step' down onto the existing concrete drive as there is no fixed object to butt up against. Therefore to restrain the paving i really need to haunch but it will look ugly.

What options could i have to restrain this outer edge.I cannot cut into the existing concrete and lay say a decorative edge and therefore something like this would still need fixing well into place.Would it be possible to say to lay the first 2 courses on a concrete bed to give extra strength and then smooth off under the outer edge of blocksto give a neat finish ? or is this just wooly thinking ! There is only light foot traffic on this area but i am conscious of Tony's insistance on locking the paving in to for the integity of the finished job.

Secondly, as i am laying only a small area onto a rigid base and intend to use the 'pre-compaction method' and as compaction is not required for the first stage can i use an alternative to a plate compactor and only hire this kit for the completion stage?I don't wish to cut corners but there may well be some time between screeding and the finishing parts as i am a little slow with my projects!

Posted: Fri Mar 30, 2007 1:07 pm
by Tony McC
For the edge course, two options spring to mind:

1 - Use a high-strength mortar to bond the edge course blocks to the concrete base. This would involve scabbling and/or acid-etching the concrete at the edge and then using a modified mortar (adding Ronafix or SBR) to firmly fix the blocks in place. Assuming no vehicles, that will probably be adequate.

2 - Use a thin edging strip, such as the steel ones from EverEdge or the very attractive aluminium type from Rite Edge, to hold the edge blocks in place.

Posted: Fri Mar 30, 2007 1:21 pm
by novicejohn
Thanks for your quick response Tony. Can you tell me what SBR stands for ? and have you any thoughts on not using a plate compactor for the pre-compaction stage.
Many thanks,

Posted: Sat Mar 31, 2007 2:26 pm
by Tony McC
SBR is Styrene Butadiene Rubber - it's a reasonably common mortar/concrete additive you should be able to get hold of at any decent Builder's Merchant (and possibly at Travis Bloody Perkins, too, but I wouldn't bet on it, and if they do have it, they'll be charging an arm and two legs!)

Pre-compaction: you should be ok doing the boot-trampling dance to partially compact the laying course prior to screeding and then using the plate for final compaction, but most people find that it costs as much to hire a plate for a week as it does for a couple of days.

Posted: Sat Mar 31, 2007 2:29 pm
by novicejohn
Thanks again Tony.....great help:great site