Civil Engineering Reference
In-Depth Information
construction. The main constituent of peat is cellulose from decomposed plants.
Dried peat can be used in building sheets and as thermal insulation. For use as
thermal insulation, it has to be worked and must contain plenty of fibres.
Sphagnum moss in peat contains small quantities of poisonous phenol com-
pounds which impregnate the material.
Grasses and other small plants represent a very large potential resource. As far
as cultivated plants are concerned, e.g. wheat, rye, oats and barley, the waste left
over after the grain has been harvested can be used.
Plant resources are seldom used in today's building industry, probably
because of their perceived ineffectiveness and because of the lack of efficiency in
the handling of the raw material, the production of the final building material
and the on-site handling.
Cultivating and harvesting
Most cultivated plant products are by-products from the production of grains.
Intensive production of grain requires the extensive use of artificial fertilizers
and pesticides.
Flax is immune to mould and insects and needs no pesticide treatment. Grain
is harvested when it is ripe, usually during late summer. Cutting of wheat and
rye for roof-covering must be carried out without breaking the stalk or opening
it up. Many wild species grow in water, e.g. reed, ribbon grass and pond sedge.
These plants live for many years, sprouting in spring, growing slowly through
the summer and withering during winter. From 1000 m
2
, 0.5-3 tons of material
can be produced. Harvesting either by boat or from the ice occurs during the
winter when the leaves have fallen.
Moss grows ten times as much in volume per unit area than forests. When har-
vesting moss, care must be taken not to destroy its system of pores. It is techni-
cally better and functionally easier if it is pulled up in pieces.
Harvesting peat is best done during the summer when the peat is at its driest.
Summers with high rainfall can cause problems during harvesting as well as in
the quality of the final product. There are machines which shave 3-5 cm off the
surface of the peat. When large areas are harvested the local ecology of the area
must be taken into account, particularly when harvesting moss and peat.
Marshes have very sensitive ecological systems which include complex animal
life. It is best to use peat resources which is likely to be wasted in cultivation for
agricultural purposes, road-building, etc.
Preparation
Most of the smaller plants must have their leaves, seeds and flowers removed
before direct use as roof-covering, thermal insulation, etc. Extraction of fibre
