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< prev - next > Construction Roofing and flooring KnO 100060_Micro concrete roofing tiles (Printable PDF)
Micro concrete roofing tiles
Practical Action
Pigments tend to be imported and therefore expensive. Their use makes the cost of the tile
significantly more expensive, but in some areas a market does exist for more expensive
coloured tiles. Pigments add nothing to the strength of a tile and may even reduce it slightly.
The production sequence
The sequence of operations to make MCR tiles is as follows:
Fill the cement and sand batching boxes fully to the top and level off. It is normal
practice to use three volumes
of sand to one of cement, so
the sand batching box is
three times the size of the
cement box.
Tip out the sand and cement
onto a wooden, plastic or
metal mixing board placed
on a table. Mix thoroughly
for up to a minute until all
the material is of one colour.
Add water to the mix
gradually, turning the mix
with a trowel all the time
until it becomes wet enough Figure 4: Fill nib forming box and insert loop of wire
to be workable. Add the
water only slowly to ensure
that too much is not
added. It is best to use a
measuring jug and to add a
measured amount of water
each time. A few trial
mixes can be made to find
out how much water would
normally be needed. If a
set of scales is available a
standard water-to-cement
ratio (by weight) can be
determined. First find out
how much cement is used
per tile by weighing out the
cement batching box
empty, then full, to obtain
the weight of the cement
Figure 5: Pull polythene sheet with wet pantile over setting
used. Mix the sand and
cement and add a
measured volume of water
until a mix of the required
consistency is obtained.
The volume of water in
millilitres is equal to its
weight in grammes and
from the weight the
water-to-cement ratio can
be calculated. A good
mix will have added to it
a weight of water equal to
half the weight of cement
(that is the water-to-
Figure 6: Making
ridge tiles