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lay for a thickncss of 1 inch a carefully prepared concrete composed of two parts of clinker
(broken to pass through a 1 inch screen) to one part of Portland cement, and then finish off up
to the required level with a coat of richer concrete well trowelled and smoothed over the whole
aroa.
The paving should be laid in alternate bays of a no greater width than 4 feet, between
narrow soft wood screeds, which should be loft in for some time during the setting of material,
and when taken out eventually, have the joints filled up with fine ash or sand. At least a fortnight's
interval should elapse after laying before the traffic is allowed to pass over. The cross
falls should not be more than 3/8 inch to the foot.
I would not generally advise the laying of concrete in situ on footways having a greater
width than 6 feet including kerb, and on no account at a time when there is a possibility of
frost.
The passing of a small wooden, light roller (having its circumference specially formed) over
the paving while in a plastic state might bo advantageously done to form a pattern surface and
help to relieve the sombre appearance, but this requires to be very carefully done.
CLINKER SLAB PAVING.
Both in London (principally suburban) and the Provinces, slabs made from clinker and
cement have now been used for several years with fairly satisfactory results, especially when
compared with the cost and durability of the materials in more general use for this purpose.
The slabs are generally made from 2 inches to 3 inches thick, and having a surface area of
about 6 square feet.
The ingredients are usually from two to three parts of clinker, crushed to a size of about
i or g of an inch, to one part of Portland ccment, mixed together with water, filled into moulds,
and then subjected to a very high pressure by hydraulic machinery until the flag has become
perfectly solid and the surplus water is squeezed out.
The slab is thon taken out of the mould, and placed on a board to set for two or three days,
after which it is up ended in a covered shed, and left to harden for at least three months boforc
being laid.
In laying they require to be carefully and solidly bedded over the whole surface in half an
inch of good lime mortar, and the joints should be swept in with lime mortar.
The space required for the machinery for making the slabs as described is about 1,000
squaro feet, to which must of course be added sufficient space for the stacking of the greatest
quantity that is likely to bo made at one time.
Tho total cost of the plant complete is estimated at £1,500, the number of men required
boing three at least and these should be able to manufacture thirty to forty slabs por diem.
1 The Hornsey Local Board are at the present time having an improvod apparatus fixed at a
cost of about £2,000, which will give a hydraulic pressure of l,0001bs. per square inch, and which
it is claimed will minimiso the cost of production, and bo able to turn out at least 100 slabs per
diem.