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stone. The surface finish shall, unless 8.4.5 Slenderness Ratio
otherwise specified, exhibit a texture
similar to that of natural stone. The Slenderness ratio is equated by using
colour and texture of the exposed (when the diameter of either an inscribed or
installed) face of cast stone should superscribed circle on the section of the
be agreed between the supplier and product, determined by the supported
the purchaser. The supplier should on plane, and the length of the product.
request supply a sample of an agreed
size for approval of the purchaser. It is The slenderness ratio SR = —dL
important that finishes are discussed with i s given by the equa tion: SR
the manufacturer, particularly where very
smooth surfaces are being considered, as
the type of finish will significantly influence where L is the product length in mm and
the overall appearance. d is the diameter of the circle.
8.4.3 Linear Dimensions The slenderness ratio should be less than
or equal to 15 for wet cast units or less
The actual dimensions of individual regular than or equal to 12 for semi-dry units.
units should conform to the declared work
Weathered section showing dimensions subject to the tolerances Alternative ratios may be used subject to
typical inscribed circle given below. Individual manufacturers may agreement between manufacturer and
specify tolerances that are tighter than purchaser and slenderness ratio is not
those in the table following page. relevant in the case of thin walled Fibre
Reinforced Cast Stone (FRCS) units
Dimension (mm) Tolerance (mm) with their enhanced tensile and bending
strength.
up to 600 +/- 2 8.4.6 Reinforcement
601 – 1000 +/- 3
1001 – 2500 +/- 4 Untreated low carbon high yield steels
2501 – 4000 +/- 5 shall have a minimum cover of 40 mm
over 4000 +/- 6 when measured from any installed
exposed face and 30 mm from any
protected face.
8.4.4 Flatness of Plane Surface Galvanised steels shall have a minimum
cover of 30mm when measured from any
Where the surfaces intended to be installed exposed face and 20mm from
exposed in the finished cast stone are any protected face.
declared by the manufacturer to be plane,
they shall not deviate from a plane by Stainless steels shall have a minimum
more than the values given below. The cover of 10mm or twice the bar diameter
units shall be tested in accordance with whichever is the greater, when measured
Appendix 1. from any exposed face.
Maximum permitted variation from plane For other reinforcement materials the
= 0.3 % of the maximum dimension of the specification is as given in BS 1217: 2008.
item or 2 mm whichever is the greater. A variety of other reinforcement materials
such as basalt fibre or fibre reinforced
polymer product are available and their
use will be drawn to the clients attention
prior to manufacture of the units.
