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Posted: Tue Apr 23, 2019 5:01 pm
by Jonhill65
Hi, I've layed hard-core then sharp sand and was wondering if I can lay the cobbles on to that or whether it needs a cement screed. The cobbles are going to have a 10mm gap between with Romex D1 added.
Many thanks
Jon
Posted: Wed Apr 24, 2019 10:15 am
by Tony McC
Are these really "cobbles" or are they actually setts?
Setts and Cobbles Definitions
Some setts *can* be laid onto sand, but then they would be jointed with a loose-fill aggregate, such as kiln dried sand or splitt. Cobbles are never (nowadays, at least) laid onto sand.
When a rigid/bound jointing medium is being used, whether it's cementitious or resin-based, the bed needs to be bound, so that usually means some form of mortar or concrete. Using a rigid or bound jointing system over a flexible/unbound bed is just asking for a failure.
Edited By Tony McC on 1556097375