Civil Engineering Reference
In-Depth Information
absorption capacity. Carpeting can be woven, knitted, tufted or needle-punched
in many different natural fibres: cotton, wool, bristles, sisal, coconut, jute and
hemp, and in synthetic fibres such as nylon, acryl, polypropylene, polyacrylni-
trile, polyester and rayon.
In the East, carpeting has been used for centuries. In Europe, hides have tradi-
tionally been used as floor mats. Here the first true carpets originated about 200
years ago. Until then, people managed with natural materials strewn on the
floor: juniper or bracken, sawdust or sand, which absorbed dust and damp. This
kept the floor clean, as it was regularly changed. Juniper also had a particularly
fresh smell. In the 1960s, wall-to-wall carpeting was introduced, transforming
the carpet from loose floor covering to an independent floor covering often laid
directly onto concrete.
The spread of this type of covering was very rapid, in housing and in build-
ings such as schools, offices, public buildings etc. In the beginning natural fibres
were used, but synthetic fibres soon took over, making up half of the market by
1967 and the majority of the market today.
Local raw materials for the production of carpeting are wool, flax, hemp and
nettles. Timber is the raw material for rayon. Sisal comes from Mexico, while
coconut is found on the coast of the tropics, where it is often an extra resource.
Synthetic fibres, e.g. polyamide, polypropylene and polyacryl, are based on
oil.
The first part of the manufacturing process is to clean the fibres. The procedure
then varies according to the technique and material used. Weaving and knitting
require spun thread. Needle-punched carpets are made of unspun wool. For nee-
dle-punched and tufted carpets, a binder is required to attach the top surface
onto a woven underlay of fibreglass, or something similar. A natural rubber glue
can be used for this, but a synthetic rubber glue is normally used.
All carpets, both natural and synthetic, can contain anti-static agents, and sub-
stances to protect them against moths and fungus - often ammonium com-
pounds. Woollen products are often impregnated with pyrethrin to protect
against moths. Jute can be sprayed during its cultivation or at the time of trans-
port, in some cases with DDT. Loose carpets are laid directly onto the existing
floor; fitted carpets are usually laid an underlay of PVC of foamed synthetic rub-
ber, but even natural rubber, cork or woollen felt are possible alternatives. The
carpets are pressed against the floor with skirting boards, or glued. Different
sorts of adhesive can be used. Joints are sewn or glued. While natural fibre prod-
ucts have their origin in renewable resources, oil - the origin for plastic products
- is a very limited resource. The primary energy consumption of plastic based
products is also very much higher. In buildings, carpets can generally cause four
particular problems:
•
static electricity
