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Directions for using
REINforced
Cement
REINforced cement will provide
an exceptionally effective and durable material if these simple
directions are followed.
General
These recommendations are in
addition to good building practise. Portland cements harden by
chemically reacting with water. It is, therefore, desirable to prevent
premature dying out of the material after application. Damp down porous
backgrounds; try to avoid very drying conditions, (hot sun and high
winds). Overlap the material as it is applied; do not apply as a series
of separate strips. Where horizontal lift joints occur, these must be
overlapped.
No additives are required with
REINforced cement and none should, therefore be used. The surface to
which the REINforced cement is to be applied should be suitable. Where
necessary a waterproof bonding agent should be used.
Proportioning the Mix
In accordance with normal
practise, the sand and cement are batched by volume using two parts of
ordinary, clean, soft building sand (to B.S.1200) to one part cement.
Fibres are added at between 25 and 30grms per Kg of cement used.
For simplicity, we recommend you
use a clearly marked two gallon (9 Litre) bucket. For each bucketful of
cement, add at least 250grms of fibres (do not consolidate the cement,
leave as poured). A suitable mix for a small mixer would consist of 4
buckets of sand, 2 buckets of cement, with at least 500grms (1/2kg)
fibres.
Mixing
The sand, cement and water are
first thoroughly mixed, and then the fibres are slowly added with
additional water as necessary. Thorough mixing, to uniformly distribute
the fibres throughout the mix, is essential. REIN fibres are not liable
to damage by extended mixing. Only sufficient water should be added to
give the desired degree of workability – excessive water is deleterious
and should be avoided. The quantity mixed per batch should be based on
the amount which can be used within the 45 minutes of mixing.
Finishing of reinforced
cement
REINforced cement provides an
ideal base coat for most conventional applied finishes, such as dry
dash, wet dash, Tyrolean, etc. Unlike conventional base coats, which
must be allowed to dry and crack before subsequent coats are applied,
REINforced cement allows these finishing coats to be applied in about 24
hours, depending on weather conditions, giving the substantial benefit
of allowing the work to proceed without interruption. It is undesirable
to delay the application of additional coats too long, as REINforced
cement provides such an impermeable surface when fully hardened that the
suction is too low to provide a good bond for subsequent coats without a
bonding agent. An attractive textured finish is easily obtained on
REINforced cement using a texturing roller. If a textured finish is to
be applied, it is essential to adequately control the suction of the
background to prevent water being drawn from material before it is
textured. White cement and cement colours, complying with BS1014 can be
used to give a durable self finish, requiring no decoration and is ideal
for flooring. Lighter shades are recommended, as they are less likely to
create problems in consistency and fading or blooming of the surface.
Protruding fibres can be removed by lightly singeing with a blowtorch
after the cement has cured.
Estimating Quantities
REIN fibres are generally
supplied in packs which are sufficient for 10sqm of rendering at 5mm
thick, allowing a margin of approx 20%. For each pack (i.e. 10sqm of
rendering) you will require approximately 33kg cement for 67kg sand, a
total of 100kg. A 50kg bag of cement, with two bags of sand will be
sufficient for 15sqm of 5mm thick REINforced mortar.
Dry block walling
The blocks are laid dry, once
the base course and DPC are laid conventionally with mortar joints.
Hollow concrete blocks of 150mm thickness give excellent stability,
although 100mm blocks can be used. If horizontal joints in the rendering
are necessary, these must coincide with the middle of the middle of the
course of blocks. Blocks are laid with a broken vertical bond as in
conventional practise. Supporting pillars, lintels etc are as for
conventional practise. This system of building should only be employed
up to single story height.
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