Building with earth - Gernot MINKE (1)

6.21
Percentage passing
100
90
80
70
60
50
40
30
20
10
Clay Silt Sand Gravel
Fine Medium Coarse Fine Medium Coarse Fine Medium Coarse
0
0.001 0.002 0.06 0.01 0.02 0.06 0.1 0.2 0.6 1 2 6 10 20 60 100
Grain size (mm)
6.22
Percentage passing
100
90
80
70
60
50
40
30
20
10
Clay Silt Sand Gravel
Fine Medium Coarse Fine Medium Coarse Fine Medium Coarse
0
0.001 0.002 0.06 0.01 0.02 0.06 0.1 0.2 0.6 1 2 6 10 20 60 100
Grain size (mm)
6.21 Grain size distribution
curve of loam used
in a brick plant
6.22 Optimised grain
size distribution curve
for adobes
6.23 Exposed earth
block wall finished
with a loam-lime slurry,
Bendigo, Australia
6.24 Bookshelves fixed
to an earth block wall
6.25 Industrially
produced unburned
lightweight bricks
If the blocks are dipped in water for a short
time to make the surface soft and pliable, it
becomes possible to build walls from earth
blocks without using mortar. These soaked
blocks can be simply stacked, as with any
dry masonry work, and they will bind. Such
work, however, requires a very fine eye and
skilled workmanship, for it is difficult to control
the horizontal joints and the pattern,
since no tolerance of mortar thickness is
available.
Earth blocks can be cut much more easily
than baked bricks, using ordinary saws, for
example, as seen in 6.20. If parts of blocks
are required, they can either be sawed right
through, or else cut to depths of about
2 cm, after which sections can be broken
off with the tap of a hammer. In place of a
saw, a groove can also be scored with a
trowel or a knife before using the hammer.
Surface treatment
If sufficiently moistened with a tool like a
felt trowel, exposed earth block masonry
with uneven surfaces or joints can be easily
smoothened. Plastering is not advisable,
since it interferes with the capacity of loam
walls to balance internal air humidity (see
chapter 1, p. 16). However, exposed earth
block masonry can, if not aesthetically
acceptable, be given a wash of loam slurry
stabilised with, for example, lime, limecasein
etc. (6.23). This wash also impacts
the wall’s surface stability (for more details
about surface treatment, see chapter 12,
p. 98).
66
Working with earthen blocks