Civil Engineering Reference
In-Depth Information
recycling of 90 per cent has been made possible (Thormark, 1995). The buildings
demolished have been older types with a simple use of materials. For modern
buildings, it is doubtful whether the level of recycling will get as high as 70 per
cent. There are also examples of successful projects in which buildings consist
mainly of recycled materials and products (Bitsch Olsen, 1992).
Recycling levels
There is a hierarchical model of recycling levels; the goal is to achieve the high-
est possible degree of recycling:
A:
Re-use
B:
Recycling
C:
Energy recovery
Re-use
depends upon the component's life span and refers to the use of the whole
component again, with the same function.
Development of re-usable structures or component design has not come very
far. There are few quality control routines for re-usable products. Efficient re-use
of materials or components demands simple or even standardized products.
Very few products on the market today meet these requirements. In Germany
there are as many as 300 000 products within the building industry, all with dif-
ferent design and composition.
The re-use of materials always
used to be a part of building practice.
In many coastal areas older buildings
have been constructed using a great
deal of driftwood and parts of
wrecked ships. Log construction is a
good example of a building method
with high re-use potential. The basic
principle of lying logs on top of each
other makes them easy to take down
and re-use, totally or in part. This
building method uses a large amount
of material, but the advantages of re-
use balance this out.
Recycling
is mainly dependent
upon the purity of the material.
Composites or multiple materials are
no good for recycling. Recycling is
done by smelting or crushing the
Figure 1.2: A traditional summer village on the south coast of
Turkey. The huts are made of driftwood, packing cases,
packaging and other available free material, and are used as
summerhouses by the local population.
