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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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