Building with Earth: Design and Technology of a Sustainable Architecture

less inclined so that the top layer has 20°
less inclination and a partial corbelling effect
can be seen. This, furthermore, has the
advantage that no sound-focusing effect
occurs (see 14.68). The blocks used were
tapered and extruded through a special
snout in a mechanical brick plant.

Domes and vaults on formwork
It is very labour- and material-intensive to
build formworks for domes, which is why
nearly all historical dome construction
techniques avoided it. An exception is the
shallow Catalonian dome (sometimes called
a “funicular shell” in India), which is essen-
tially a bell-shaped dome that can cover
triangular, square, rectangular or other
shaped bases. Timber boards, steel sheets
and glass-fibre reinforced polyester ele-
ments have been used for the formwork.
It is, however, much easier to make a form-
work with moist sand, as shown in 14. 70.
When constructing vaults, it is much easier
to build a formwork, as these only have
singly curved surfaces. Furthermore, only a
short piece of formwork can be used and
shifted as the vault construction proceeds.
This technique is normally used to construct
jack vaults (see 14 .14). The jack vault shown
in 14.69was built on a sparse formwork,
erected on thin laths positioned underneath
the joints of the earth blocks. These blocks
were arranged without mortar. The joints
were later moistened, and then mortar was
filled in from above.

Firing of earthen domes

The Persian architect Nader Khalili has

constructed several earthen domes in Iran

and in the USA, which he attempted to

strengthen subsequently by firing them

from the inside. While the combination of

the four elements used to create these

spaces, earth, water, air and fire, may lend

them a mystic touch, they yet have several

disadvantages regarding climate and exter-

nal environment. The burning of the logs,

branches and twigs creates pollution and

consumes large quantities of energy. Fur-

thermore, the burning process cannot be

fully controlled and is hence not optimum.

The uneven heating of the blocks may pro-

duce cracks reducing structural stability.

Also, most of the pores in the blocks are

closed by burning, drastically reducing their

capacity to absorb and desorb humidity

(see chapter 1, p. 14). This, however, means

failing to exploit the principal advantage of

loam as a building material.

130 Designs of building elements

14.69 Jack arch with

Formwork

14.70 Dome, utilising

moist sand as formwork

14.71 Completed vault

in a private residence in

Kassel, Germany

14.72 to 14.73 Desert

Research Institute, Sadat

City, Egypt

14.74 to 14.75 Wissa

Wassef Centre, Cairo,

Egypt

14.69 14.70

14. 71