Building with Earth: Design and Technology of a Sustainable Architecture

Frame structure with rammed earth infill

At the Centro de Pesquisas e Desenvolvi-

mento, (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 form-

work, so that either no formwork or only

one-sided formwork is required. It is also

advantageous if this formwork can con-

tribute to a substantial increase in thermal

insulation. The stiffness of this lost formwork

has to be sufficient to take care of the later-

al impacts created by ramming. Illustration

5.29shows 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 compo-

nents. In the section shown on the right,

the lost formwork is on the outside and

is made from stabilised lightweight soil

blocks.

Illustration 5.30shows 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-fabri-

cated 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.

57 Rammed earthworks

5 .19 5.23

5.20

5.22

5.21