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To obtain this mixture, the soil is treated in four
different steps:

Batching and addition of additives

Dry mixing

Ageing

Wet mixing
Keeping the basic steps same the process of soil
preparation varies depending upon the general
practice followed in various regions. Mostly they can
be classified broadly into four different categories:

Manual mixing

Semi-mechanised mixing

Filtration techniques

Other mixing techniques
Internal fuel is added depending on its quality, soil
characteristics and external fuel consumption.
Convert the internal fuel and other additives
from weight to volume basis. For this you need to
construct a cft box. It is a wooden box having internal
dimensions 1ft x 1ft x 1ft. It also has two handles on
two ends for easy handling and transportation.
Convert the material to be added from weight into
volume.
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Each of the process has been discussed in greater
detail below.
Manual Mixing
To make good quality green bricks, the dry lumpy
soil has to be mixed uniformly with additives and
then turned into a smooth, soft paste.
Batching and Additives
After digging or transporting the soil, it is spread
evenly over the mixing area. The lesser the pile
height, the better the mixing in lesser time. Take
eight fired bricks from your area. Around the soil
pile keep them in an octagonal pattern on the
height. Thus the height of the soil pile can now
be measured to one brick length. Spread the soil
evenly to this brick height. You will require to move
the bricks to widen the pile. The dummy bricks can
now be taken out. Always perform this step before
adding other materials.
Sieve the additives in a 2 mm mesh before mixing.
However the rice husk if added does not require
any sieving since it is of uniform size. Keep aside
the sieved material that passed through the 2 mm
mesh. Sieving is of utmost importance since any
particles bigger than 2 mm will make the fired brick
weak due to absence of any binding with the soil
matrix.
Depending on soil plasticity, anti-shrinkage materials
like stone dust, fine sand, boiler ash are added.
Figure 18: Manual Mixing Process
Add one material at a time. Preferably the low
density materials should be added first i.e. internal
fuel and then stone dust. For all purposes, rice husk
to be added at the last. The material to be added
should be spread uniformly over the pile. If in any
place there is a cluster of additives spread uniformly
over the soil by hand. Repeat the process similarly
for other additives.
Dry Mixing
After the materials are added, the pile should be
dry mixed at least two times. Dry mixing should be
started from one end only. Never start dry mixing
from two ends by two persons. For dry mixing
use a spade have a blade length of more than 9
inches. This will ensure that during cutting the blade
GREEN BRICK MAKING MANUAL
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