Civil Engineering Reference
In-Depth Information
10
Plants
'The forest gives generously the products of its life and protects us all.'
Pao Li Dung
Until the introduction of steel construction at the beginning of the industrial
revolution, timber was the only material with which man could build a com-
plete structural framework. Timber unites qualities such as lightness, strength
and elasticity. Compared with its weight, it is 50 per cent stronger than steel. It
is more hygienic than other similar materials - the growth of bacteria on
kitchen benches of timber is much lower than that on benches of plastic or
stainless steel. Timber also has good thermal conductivity. These qualities,
mean that, in relation to most modern European building standards, timber can
be used in up to 95 per cent of the components of a small building. This
includes everything from roof covering to furniture, thermal insulation and
framework.
Other plants can be used in building, though their use as a structural material
is the exception rather than the rule. Examples exist along the rivers of eastern
Iraq, where bunches of papyrus have been tied together to carry walls and ceil-
ings, a building technique that is 5000 years old.
There are many non-structural uses for plants from living, climbing plants,
which act as a barrier against wind and weather to linseed oil from the flax
plant, used in the production of linoleum and various types of paint. Wood
tar and colophony can be extracted from wood for use in the painting indus-
try, the glue lignin, vinegar and fats in the form of pine oil for the production
of green soap. Copal is extracted from many different tropical woods and is
used as a varnish. Natural caoutchouc from the rubber tree can be used in its
crude form as a water-repellent surface treatment or as the starting point for
the production of plastics, e.g. chlorocaoutchouc, formed from a reaction with
chlorine.
