Civil Engineering Reference
In-Depth Information
Work hours/m
2
Work hours/m
2
Method
net
gross
Machine ramming
3.5
5.0
Ramming by hand
5.5
7.0
Blocks by machine
3.5
5.0
Blocks by hand
5.5
7.0
The equivalent for a fully completed concrete wall with surface treatment is
3.3 hours/m
2
whereas a brick wall takes 3 hours/m
2
, but the figures only take
into account the amount of work carried out on the building site. In the case of
concrete and brick a large amount of work has been done before the materials
actually arrive at the building site. The difference between these methods would
be drastically reduced if these aspects were also considered, but there is little of
a complete assessment of the different methods.
According to Gernot Minke of the Technical High School in Kassel, research
and development of partly-mechanized earth building techniques is going to
make this technique much more efficient in the near future. Working with the
extruded earth method, an 80 m
2
house, both inner and outer walls, can be built
in three days using four builders who know the techniques. A conventional earth
house of the same size would take 14 days to build.
Earth buildings and indoor climate
A completed earth house has a high-quality indoor climate. Earth is a very good
regulator of moisture compared to many other materials. The walls are relative-
ly porous and can quickly absorb or release moisture into the room. The relative
humidity of the inside air will usually be around 40-45 per cent. An investigation
has been conducted in Germany amongst people living in stone, brick, concrete
and earth buildings. Those in earth buildings were, without exception, satisfied
with the indoor climate of their homes. This satisfaction was seldom found
amongst the people in the other house types. These, perhaps subjective feelings,
have only been partly scientifically proved. It is not only earth's property of
moisture control that should be taken into account, but also other factors such as
its absorption of gas and odours, its warmth capacity, its acoustic properties of
reducing noise levels and even certain other psychological aspects.
Plastic structures
Plastic is seldom used as a structural material. The large amount of unspecified
plastic waste which now exists in the Western world is a possible raw material
