Building with Earth: Design and Technology of a Sustainable Architecture

Rammed earth domes

Probably the first rammed earth dome was

built by the BRL in Kassel, Germany, in

1983 using a special technique developed

by that laboratory. This consists of a rotating

slip form in which the earth is rammed

(5.31, 5.32,5.33).

The thickness of the dome was 18 cm at

the bottom and 12 cm at the top. The walls,

which form a hexagon on the inside, were

also made of rammed earth. In order to

transfer the thrust from the dome to the

foundation, buttresses were integrated with

the walls. The shaping of the top of the but-

tresses as well as the windows was done

with a kitchen knife soon after the form-

work was dismantled. The formwork of the

wall was custom-designed according to the

plan of the dome, as seen in5.31. The earth

was rammed into the formwork using a

vibrator, described on p. 55 in this chapter

(see 5 .12), and by hand.

The dome formwork itself was so designed

that it could be lifted not just at the centre,

course after course; it also had a guide that

automatically adjusted the radius and incli-

nation of the formwork (5.33).

Drying

It is seldom possible to say when a loam

wall is dry, but the drying process is in any

case faster than those of masonry or con-

crete walls (see chapter 2, p. 28). Given dry

warm weather and sufficient air movement,

shrinkage stops after just a few days. After

three weeks, the wall feels completely dry,

although water content is still slightly higher

than the equilibrium moisture content.

59 Rammed earthworks

Plaster

Soil blocks

Thermal insulation

Lightweight loam

Soil blocks

Timber panels

Protection layer

Thermal insulation

Lightweight loam

Gypsum board

Plaster
Thermal insulation
Lightweight loam
Lightweight loam board
Mud plaster

Bricks

Lightweight loam

Thermal insulation

Mud plaster

5.30

5.26

5.28 5.27