Building with Earth: Design and Technology of a Sustainable Architecture

Tools

In former times, earth was rammed manual-
ly, using rams with conical, wedge-shaped
or flat bases (5.7).
If conical or wedge-shaped rams are used,
the different layers are better mixed and,
provided there is sufficient moisture, a bet-
ter bond is obtained. However, this takes
more time than ramming with flat-based
rams. Walls rammed with flat-based rams
show less lateral shear resistance and there-
fore should only be loaded vertically.
The base of the ram should not be too
sharp, so that the formwork, if made of tim-
ber, is not damaged. The base should be
no smaller than 60 cm^2 , and no larger than
200 cm^2. The weight of the ram should
be between 5 and 9 kg. It is preferable to
use a two-headed ram with a round head
on one side and a square one on the other.
This allows the ram to be used with the
round side for general work, and with the
square edge to compact corners effectively.
Such a ram is used even today in Ecuador
(5.8).
Electric and pneumatic rams were used as
early as the second quarter of the 20th cen-
tury in Germany, France and Australia. The
electrical ram shown in 5.9, built by the Ger-

man firm Wacker, was often used in former

times for rammed earth work, and has been

written about extensively. It has a hammer-

like action with a lift of 33 mm, and a fre-

quency of 540 strokes per minute. The ram

is very effective; its only disadvantage being

difficult in handling, since it weighs 24 kg. It

is no longer manufactured.

In Australia in the 1950s, a pneumatic ram

was used (5 .10). This acts like a jackhammer,

has a frequency of 160 strokes per minute,

and weighs 11 kg.

54 Rammed earthworks

5 .13

5.8

5.6 5.7

5.9 5 .10

5.6The circular barn,

Bollbrügge, Germany

(18 31)

5.7Rams used for

manual compacting

5.8Two-head ram

used in Ecuador