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Posted: Thu Feb 03, 2005 7:38 pm
by Boardman
Would anyone know what the differnce between dolomitic & quartzitic limestone would be, is one more durable than the other?
Also in the Stonemarket brochure they recommend using PVA additives to bond the flags underside onto the bedding mix due to the stones density & low water absorption ( I was looking at their Trustone Cotsdale paving). Is this essential or not?
Posted: Thu Feb 03, 2005 11:16 pm
by Tony McC
The diff between quartz-rich, dolomitic, magnesian, carboniferous, oolitic and all the other liemstones is one of geochemistry. There's no straightforward answer that ALL dolomites are wonderful sub-base materials and all oolitics are crap (although there's a fair deal of truth in that statement!) as limestones vary enormously throughout Britain and Ireland, and the rest of the world.
The guff about using PVA is exactly that: guff. We've been laying stone flags for a few thousand years now - how did we ever manage before the advent of PVA?
I think the thought-process behind Stonemarket's suggestion is based on the mistaken belief that flags have to "stick" to the laying course, like tiles to a kitchen floor. As I've said to Stonemarket, and several other manufacturers in the past - if they'd leave off telling folk how to lay flags, I'll not tell folk how to make them! 