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Stone Sett Pavings |
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Hard Landscape |
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Granite whinstone and gritstone setts can all be laid to produce a hard paved surface for pedestrian and light vehicular use. This note gives general guidance on the materials and techniques employed in new work.
SETTS
New cleft setts should not show any drill holes and should be hand hewn on all faces to reduce the protrusions. All dimensions should be within 10mm of the nominal dimensions, which are frequently 200 long x 100 wide x 100 thick (mm) or 100 x 100 x 100rnm.
Unbroken and undamaged secondhand setts are generally suitable for re-use, but they must be cleaned by hand on all faces, back to the parent stone, before being relaid.
Subgrade
After any necessary excavation to levels, the subgrade should be thoroughly compacted with a light roller before laying the sub-base.
Sub-Base
The sub-base should consist of 100 to 150mm layer of well graded granular material, passing a 75mm BS sieve. In general, quarry waste, crushed rock, crushed brick or concrete, hoggin and gravel are all suitable.
After placing in one layer, the sub-base should be thoroughly compacted with a light roller.
Concrete Base
For small areas and for very light pedestrian traffic, no concrete base is necessary.
In all other cases, a base course of grade C20 concrete, nominally 150mm thick, should be laid.
Bedding
Setts are laid on to a 50mm thick bedding. When a concrete base is used this bedding can be fine clean dry sand, free from pebbles. In all cases where there is no concrete base, 3:1 dry sand: cement mix should be used.
Laying
Setts should be laid in parallel on concentric courses with the longest edge dimension approximately at right angles to the direction of vehicular traftic, where possible. A variety of patterns can be used, but at the edges, two or three courses should be laid parallel with the boundaries.
Adjacent setts should be selected and laid, with due regard to tolerances so that the surface joints do not exceed 15.
Any sett with a pronounced taper should be laid on its larger face dimension.
After laying, setts should be rammed down to a firm seating in the bedding, and to give a level surface. Alternatively, vibro-laying techniques may be used to achieve the same end.
Joints Filling
Joints may be filled with a hot bituminous compound and immediately sprinkled with sand, or with well-compaced 3:1 dry sand: cement which is then lightly watered with a very fine spray. Pumping sand: cement slurry into the joints can also be successful. Traffic should not be allowed on the setts for 3 days after joint filling.
Reference
BS 435:1975 "Dressed Natural Stone, Kerbs, Channels, Quadrants and Setts".
Other Data Sheets
Mortar and Pointing
Guide to the Tests for Natural Building Stone
Stone in Civil Engineering
Damp Proof Courses in Stone Work
Considerations to Reduce Staining on Natural Stone Facades.
Laying Marble and Granite Tiles on to an Existing Timber Floor
Sealing joints in natural stone cladding
Information Leaflets
Natural Stone Flooring and Paving
Fixings for Stone Cladding
Care and Maintenance
Sandstone
Limestone
Marble
Granite
Slate
Stone Walling
Stone Cleaning and Surface Repair
Restoration |
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