Building with earth - Gernot MINKE (1)

5.20
Frame structure with rammed earth infill
At the Centro de Pesquisas e Desenvolvimento,
(CEPED) in Salvador, Brazil, a simple
technique was developed to construct thin
rammed earth infill panels. It was used in
several low-cost housing projects in Brazil.
The posts and ring beams were normally
made from pre-cast reinforced concrete.
The sides of the formwork were directly
mounted on the posts. Thus, the thickness
of the wall was the same as that of the post
(5.26). In this case, the loam was stabilised
with 6% to 8% of cement.
Wall construction with lost formwork
As with rammed earth techniques, the cost
of the formwork is quite high. In some
cases, it is preferable to use a thin masonry
wall or stiff thermal insulation elements
made of wooden materials as lost formwork,
so that either no formwork or only
one-sided formwork is required. It is also
advantageous if this formwork can contribute
to a substantial increase in thermal
insulation. The stiffness of this lost formwork
has to be sufficient to take care of the lateral
impacts created by ramming. Illustration
5.29 shows horizontal sections through an
external wall. The first two cases show an
inner leaf built of adobes or soil blocks and
an outer rammed earth layer made with
lightweight mineral loam which is directly
plastered. In this case the formwork is only
required for the outer face. In the second
case, a somewhat better stiffness of the
inner adobe or soil block leaf is attained
due to the bonding pattern in the components.
In the section shown on the right,
the lost formwork is on the outside and
is made from stabilised lightweight soil
blocks.
Illustration 5.30 shows vertical sections
of external walls that have lost formwork
on both sides. The inner leaf can be made
from adobes or soil blocks, larger pre-fabricated
loam elements, or stiff plywood
boards, fibre-reinforced gypsum boards,
or Magnesite or cement-bonded wood
particleboard.
Protection of the wall surface against the
elements can be achieved by plaster,
masonry or timber panelling with air cavity.
5.21
5.19 5.22
5.23
57
Rammed earthworks