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

mould

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

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