Building with earth - Gernot MINKE (1)

Nubian domes
The Nubian dome technique has been
known in Upper Egypt for thousands of
years. In this technique, circumferential
courses of adobes are laid using a movable
guide (14.62).
With this technique, blocks are turned on
edge. This avoids slippage of the freshly laid
blocks. However, this requires that special
wedge-shaped blocks be used periodically
(14.63). Due to the high labour input
required most domes were built without
turning the blocks, that is, placing them in
radially.
The main disadvantage of the Nubian
domes technique is that only spherical
domes can be produced. As explained in
this chapter, p. 116, in spherical domes, tensile
ring forces occur in the bottom
portions. Therefore, when covering larger
14.59
14.61
spans, steel strips or reinforced concrete ring
beams or other strengthening elements
have to be additionally applied. If this is not
considered, domes might fail, as has happened
in practice.
The group Development Workshop,
Lauserte, France, built several residences,
offices and public buildings in Niger using a
modified version of this technique, shown in
14.64. Here, instead of the centrally mounted
rotating guide, an eccentric rotating
guide is used. By this, the shape generated
can be such that the tensile ring forces in
the lower part are avoided. However, compressive
ring forces thus created might
cause problems if larger openings are made
for entrances or windows.
14.59 to 14.60 Models
of different dome shapes
deriving from the Nubian
and Afghan techniques
(BRL)
14.61 Persian dome
with wind catchers
14.62 to 14.63 Nubian
dome (CRATerre, 1979)
14.64 Modification
of Nubian dome with
eccentric guide
14.65 to 14.68 Prototype
dome (BRL)
14.60
126
Designs of building elements