Building with earth - Gernot MINKE (1)

14.17
14.18
14.19
spaces thus created are then filled with a
third layer of loam mortar stabilised with
6% to 8% (by volume) of double-boiled linseed
oil. The surface is then smoothed by
rubbing with great pressure using a metal
trowel (14.19) until the surface becomes
shiny.
Since this process is very labour-intensive,
the author of this study has developed an
alternative design requiring significantly less
labour (less than a fifth):
The layers constituting this floor can be seen
in 14.21. In order to break up capillary
action, the lowest layer is formed by coarse
gravel. A damp-proof coarse of bituminous
felt paper is laid over this, followed by a
base thermal insulation layer of rockwool.
(The latter is necessary only by the stringent
demands for thermal insulation contained
in more recent German regulations; otherwise
lightweight loam would be sufficient.)
14.20
A 12-cm-thick lightweight mineral loam is
poured on top of this layer. This provides
both sufficient thermal insulation and the
required structural strength.
The lightweight loam was prepared in a
normal concrete mixer and then poured
from a wheelbarrow (14.22).
In order to reduce hardening time, 4%
cement was added to the mix. In order to
achieve adequate surface hardness, a
3-cm-thick loam mortar (containing sufficient
coarse sand to minimise the occurrence
of shrinkage cracks) was applied in
two layers. For this mortar, 6% (by dry
weight) of three different stabilising agents
were successfully tested: the first, soda
waterglass was added after being thinned
1:1 with water; the second, double-boiled
linseed oil; and the third, lime-casein glue
(made from 1 part hydraulic lime and
5 parts fat-free white cheese mixed vigor-
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Designs of building elements