Building with earth - Gernot MINKE (1)

14.69 14.70
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 essentially
a bell-shaped dome that can cover
triangular, square, rectangular or other
shaped bases. Timber boards, steel sheets
and glass-fibre reinforced polyester elements
have been used for the formwork.
It is, however, much easier to make a formwork
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 14.69 was 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.
14.71
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 external
environment. The burning of the logs,
branches and twigs creates pollution and
consumes large quantities of energy. Furthermore,
the burning process cannot be
fully controlled and is hence not optimum.
The uneven heating of the blocks may produce
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.
14.69 Jack arch with
minimised 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
130
Designs of building elements