with 800 kgs of soil. However, dry cement and dry powdered soil have very similar
"densities", so if it is easier to measure by volume (for example a bucket full or a wheelbarrow
full) then your results should be okay. Make sure that you write down which measure you
used in your tests - volume or weight.
DENSITY: A 50 kg bag of cement will fill a box that is 30 centimetres (cm) long, 30 cm wide
and 30 cm deep. The volume of the box is 30 x 30 x 30 = 27,000 cubic centimetres. The
density of the cement is 50 kgs per 27,000 cubic centimetres. We usually make this number
tidier so that we can compare the densities of different things;
50kgs/27,OOOcm3 = 1 kg/540cm3 = 1852 kg/m3
Density is usually given in kg/m3. Examples of densities are: Mild Steel = 7,800kg/m3; Wood
= 4,000 to 8,OOOkg/m3 ; Ice = 920kg/m3.
Now you should have some idea of which stabiliser and how much to use with your soil. If
you are making a lot of blocks, then you should have some tested for water absorbtion and
wet strength when crushed. The Standard Association of Zimbabwe can carry out these tests.
They will tell you how many blocks you need to take for testing (probably 10). However, if you
are building a very simple structure or building outside city limits, then you can just take a
few blocks to get an idea of their strength.
SOIL PREPARATION
We will deal
more with
testing
blocks in
section 5.
Remember
to keep good
records of
the soils
that you
test. When
it comes to
making
sample
blocks for
testing you
must have
good records
of which
block has
which
stabiliser
and how
much.
When you
dig your soil
it may be
wet or dry.
Dry soil is
easier to
prepare and work with. If your soil is wet leave it to dry out in the sun turning it sometimes.
Dry soil should be crushed using tools like punners or hammer-hoes as in the picture below.
9