Building with Earth: Design and Technology of a Sustainable Architecture

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 con-
trol 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, lime-

casein 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

100

90

80

70

60

50

40

30

20

10

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 1 00

Clay Fine MediumSilt Coarse Fine MediumSand Coarse Fine MediumGravel Coarse

Percentage passing

Grain size (mm)

100

90

80

70

60

50

40

30

20

10

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 1 00

Clay Fine MediumSilt Coarse Fine MediumSand Coarse Fine MediumGravel Coarse

Percentage passing

Grain size (mm)

6.21Grain size distribu-

tion curve of loam used

in a brick plant

6.22Optimised grain

size distribution curve

for adobes

6.23Exposed earth

block wall finished

with a loam-lime slurry,

Bendigo, Australia

6.24Bookshelves fixed

to an earth block wall

6.25Industrially

produced unburned

lightweight bricks

6.21

6.22