Pic 2. Wet clay rolled into a sausage shape 100 mm in length
Pic 3. In this example the clay had shrunk to 93 mm a shrinkage
rate of 7% which is acceptable
of its length. Therefore, in this
example it should still be at least
90 mm (see pictures 2 and 3).
2.2. Inspection using the senses
Firstly it is possible to get an indicator
of the amount of clay contained in the
soil by simply looking at the surface
of the earth; if large cracks are
found on the surface there is a good
chance that there is clay present. You
can also test the quality of the clay
through touch. If the soil is clayey
you will find it difficult to crumble it
in your fingers. Furthermore, when
you mix the clay with a little water if
the soil is clayey it will stick to your
hand and leave a stain.
2.3. Testing with a bottle:
a) Prepare a clean and transparent bottle which one could see
through. Partially fill the bottle with soil and add water.
Shake the mixture well and put the bottle in a suitable
place and leave to settle. After two hours lift the bottle and
examine its contents.
b) Normally the more coarse particles of sand will form in
layers at the bottom with the soft mud layer on top. The
amount of mud in the soil is determined according to its
height. For good quality unburnt bricks the level of mud
should at least exceed 60%.
c) If the clay you test has in excess of 60% mud then it is
suitable for use and should be mixed with animal dung or
grass. If the mud content is less than 60% it should not
be used.
Practical Answers Sudan
The Construction of the Timberless House Model