Civil Engineering Reference
In-Depth Information
for simple structural elements. Polystyrene waste can be cast into solid beams
and columns if supporting substances are added in proportions of 10-15 per
cent. The structural properties are approximately the same as timber, and com-
ponents can be sawn and nailed. The concept is interesting and still being devel-
oped in England and Sweden. There is little evidence to assess its durability and
workability with other products. Polystyrene and a large proportion of additives
could possibly have unfavourable effects on the indoor climate, and pollution
could occur when the products become waste materials.
Timber structures
Timber has been the main structural material for the nomad's tent and the
farmer's house and fencing in all corners of the world, especially in the case of
roof construction, in which its lightweight and structural properties have made
it more attractive than any other alternative.
High-quality timber is stronger than steel when the relative weight is taken
into account, and the environmental aspects are considerably better. Timber
structures have been limited to small buildings because of fire risk, but now there
are many developments in the use of timber in larger buildings. The reasons for
this are the improved possibilities for technical fire protection and the revised
view of timber's own properties in relation to fire, which are better than previ-
ously thought. In timber of a certain size, the outer carbonized layer stops further
burning of the inner core of the timber.
History
The first mention of buildings constructed completely from timber in European history
is in Tacitus. Tacitus writes about Germanian houses in his
Histories
in AD 98, char-
acterizing them as something 'not pleasing to the eye'. The houses had either palisade
walls with columns fixed into the earth or clay-clad wattle walls. They had thatched
straw roofs. Excavations from a Stone Age village in Schwaben, Germany, showed
that houses like these have been built over a period of at least 4000 years.
Excavations of a Bronze Age village on an island in a Polish lake uncovered houses
built of horizontal planks slotted between grooved posts. The palisade wall went
through many improvements on the Continent and received a bottom plate, amongst
other things.
Remains of log timber buildings from about 1200-800 BC have been found in the vil-
lage of Buch outside Berlin. Even in China and Japan there are traces of this technique
from an early period, but most likely from a completely separate tradition to that of
Europe.
In areas where there is a milder climate, such as the British Isles, the coasts of the con-
tinent and Scandinavia, an alternative structural technique developed alongside log con-
struction - the stave technique. This technique is best exemplified in all its magnificence
