Earthquake protection for poor people’s houses
Practical Action
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Each separate roof member should be tied to the ring beam and if a lightweight roof is used the
ring beam should be tied to the wall at regular intervals. The ring bean should also be
strengthened at all corners.
Apart from these continuous reinforcements, which may be expensive and not necessary in all
cases, local reinforcements can be placed in high-stress areas only. These might consist of
wooden or steel dowels which are braced, or of wire-mesh or bamboo strips laid in horizontal
joints over a short distance, for example, 50-100cm along the walls next to a corner.
Blocks and mortar
Good-quality blocks and mortar are also crucial. Since the mortar takes care of the bond, it
should be of at least as high a quality as the blocks. There is a lot of literature available on earth
construction which will go into further detail; but here are some key points:
Select your soil carefully, with enough clay to bind it, but not so much as to cause
shrinkage, and enough sand to provide strength.
Break and mix the soil well; do not use too much water in the block production, and cure
blocks gradually, under cover.
Include some grass, straw or bagasse (sugar-cane residue) to help prevent cracks and to
increase the strength of the adobe.
Increase the compaction to improve strength: instead of hand-moulding, a steel press,
such as a Cinvaram or Terstaram, can be used.
Stabilize the soil to increase the strength and water resistance further; possible
stabilizers are cement, lime, lime pozzolanas, bitumen and gypsum, and these can be
added to the soil in the proportions of between 5 and 10 per cent by volume.
Make adobe blocks quite shallow (less than 10cm thick) and large, to achieve a good
bond in walls.
6