APPROPRIATE TECHNOLOGY FOR LOW COST HOUSING
Building with appropriate technology Soil Stabilized
Blocks
The technology:
Ordinary (red) soil is stabilized with cement or lime and compressed
using a manual machine called the BLOCK PRESS. Red means removing the
top (black) soil and using the soil, which is free of organic material.
Stabilization mans the block will not disintegrate (washed away) because
of rainwater.
The Block Press Machine:
This machine commonly referred to as THE SOIL BLOCK PRESS is probably
the best after years of building research and a development by a Kenyan
NGO called APROTEC. The machine makes SOIL STABILIZED BLOCKS (SSB) for
building all types of low cost houses (including Uniports), low cost water
tanks, septic tanks for sewage, pit latrines, and community houses.
With one stroke the prepared soil is compressed by 40% manual power.
The second stroke just rejects the fresh block from the mould. The machine
is purely manual, operated by two people and requires simple greasing
and oiling.
The blocks are sun-dried (NOT FIRED as is the usual case) and are ready
for use within 10 days. This tremendously reduces the fuel-wood consumption
(as in case of brick firing) and thus a contribution towards environmental
conservation. Two people operate the block press and produce 400 - 500
blocks per day.
BLOCKS PRODUCTION:
1. The red soil is sieved with a 5 mm sieve (coffee tray) while still
dry.
2. The sieved soil is mixed thoroughly with cement in the ratio 1 cement
to 15 soil by volume. (If lime is used, the ratio is adjusted to 1:8).
Soil with sharp stones works best. So an adequate amount of sharp stones
need to be present for a best block quality.
3. The mixture is wetted (using a watering can) so as to make it just
damp not very wet.
4. Fill the Mould box of the machine with prepared wetted mixture.
5. Press and then eject the formed block.
6. Refill the mould box and repeat process for more blocks
7. Cover the fresh blocks with a black polythene sheet for five days
8. Remove the black polythene sheet and let the blocks dry in the sun
for another five days
9. The blocks are then ready for use either on that site or to be transported
to another site.
QUANTITY AND SIZE OF THE BLOCKS
a) One bag (50 Kg) of cement makes between 120 - 150 soil stabilized
blocks. The best soil is murram (150 blocks) and the worst is soil without
any stones in it (120 blocks) of less quality.
b) Two people can make between 400 - 500 blocks per 8-hours working day.
c) The blocks are of standard size (280 x 140 x 110 mm) or 11.5 x 5.5.x
4.5 inches.
SPECIAL DESIGNS OF THE BLOCKS:
The mould box is specially designed to produce specially designed and
high quality soil stabilized blocks with the following shapes:
a) Ordinary solid blocks for building
b) Interlocking solid blocks for building
c) Interlocking keyed-surface blocks for building and water tanks
d) Fully interlocking keyed-surface blocks for building and water tanks
The fully interlocking keyed-surface blocks are the best of the four
and are the focus of the present project to be promoted.
SPECIAL FEATURES OF THE BLOCKS:
The fully interlocking keyed-surface blocks are specially designed:
a) Fully interlock on four sides to increase wall strength and save mortar
b) Plastering surfaces keyed to ease and reduce plastering
c) Blocks for water tanks, septic tanks, Uniports and pit latrines are
specially curved so as to make circular shapes; so there are no corners,
which would be the weak points on the wall.
d) Pit latrines may be constructed any where (swampy, sandy or rocky areas)
below the ground.
ENVIRONMENTAL ADVANTAGES OF SOIL STABILIZED BLOCKS:
a) The blocks are not fired but simply dried. This means that there is
less effect on the environment in terms of forest destruction to get firewood
for firing/ burning bricks (as is common practice), less environment pollution
with smoke, no fuel costs and the environment is saved.
b) Blocks are made on site thereby avoiding unnecessary transport costs,
handling charges and reduced damages, labour.
c) Soil is abundantly available on site e.g. from a pit latrine, soak
pit, septic tank, building foundation, etc.
d) The interlocking mechanism of the blocks greatly reduce building mortar
and increases speed (1 bag of cement binds 350 blocks). Less cement is
used and so less money spent.
e) Keyed surface means that very little plastering inside the house. The
outside may be left un-plastered for beauty.
f) When all costs are considered, building with Soil Stabilized Blocks
is about 35% a lot cheaper than using concrete blocks. It is a lot cheaper
than using any other type of bricks/ blocks and is very strong.
g) Concrete blocks, if desired may be produced using the same machine.
h) Labour requirements are minimal. Two people make 5000 blocks in 10
days which are just enough for a one 3 bed roomed house or 17 water tanks
(3000 litres capacity) or 5 double room uniports.
BASIC REQUIREMENTS:
To get the project moving and started, FADECO would need to acquire just
two machines (one for straight interlocking blocks and another for curved
interlocking blocks). Each of these machines cost Us 1000.00 (i.e. Us
$ 2000.00 for the two machines). (Uganda Shillings 1.7 Mln each i.e. 3.4
mln for two).
With these two machines, FADECO would be in position to develop rural
communities by assisting the people to make their own blocks for the construction
of houses, round houses (uniports), pit latrines, water tanks, granaries
for storing and drying foods, etc.
Why not give it a try ? It is cheap, affordable and environmentally friendly.
For more information write to us or just send an email by simply clicking
here.
Sekiku Joseph
Project manager - FADECO
P.O.Box 223
Karagwe - Kagera region
Tanzania
Fax/Tel: +255 28 2223024
Mobile: +255 744 605682
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