What is Asbestos and Why does it pose so many problems?
All asbestos is a class 1 – carcinogen (cancer forming) material
Asbestos is the
name for several silicate minerals which are highly fibrous with separable long thin fibres. The word asbestos is
derived from the Greek adjective meaning inextinguishable. The Greeks termed asbestos as the miracle mineral because
of its soft and pliant properties, as well as its ability to withstand heat. Asbestos fibres are strong and flexible, having
a tensile strength far greater than steel, yet flexible enough to be spun and woven. Asbestos is resistant to fire and heat,
it is a poor conductor of electricity and has excellent thermal and acoustic properties. Certain types are highly resistant
to acids and alkalis. Asbestos has been widely used for many industrial and commercial uses.
The two main groups that asbestos are referred to are:
1. Serpentine. (Chrysotile – white asbestos) - Mineral or rock consisting mainly
of the hydrous silicate of magnesia.
2. Amphibole. (Amosite – brown asbestos & Crocidolite – blue asbestos)
A group of minerals with similar crystal structures containing a silicate chain and combinations of chiefly sodium, calcium,
iron and aluminum.
These are the most common types of these asbestos minerals. Other types are Anthophylite, Tremolite and
Actinolite.
Asbestos became increasingly popular amongst manufacturers and builders in the late 19th century due to its resistance
to heat, electricity and chemical damage, its sound absorption and tensile strength.
When asbestos is used for its resistance to fire or heat, the fibers are often mixed with cement
or woven into fabric or mats. Asbestos was used in some products for its heat resistance, and in the past was used
on electric oven and hotplate wiring for its good electrical insulation at high temperatures, and in buildings for
its flame resistance and insulating properties, it's tensile strength flexibility, and resistance to chemical
attack.
Asbestos is known to cause serious illnesses, including malignant mesothelioma, lung cancer and asbestosis (also called pneumoconiosis).
White Asbestos
Chrysotile asbestosis is obtained from serpentine asbestos rocks which are common throughout the world. Chrysotile
asbestos fibers are curly unlike fibers from amosite asbestos, crocidolite asbestos, tremolite asbestos, actinolite asbestos,
and anthophyllite asbestos which are needle-like. Chrysotile asbestos, along with other types of asbestos, has been banned
in the United Kingdom and Europe. Chrysotile asbestos has been used more than any other type and accounts for about 95% of
the asbestos found in buildings. Applications where chrysotile asbestos has been used are within corrugated asbestos cement
roof sheets typically used for outbuildings, warehouses and garages. It is also found as flat sheets used for ceilings and
sometimes for walls and floors. Numerous other items have been made containing chrysotile asbestos including brake linings,
cloth (textile asbestos) behind fuses (for fire protection), asbestos pipe insulation, in floor tiles and in rope seals to
boilers.
Brown Asbestos
Amosite asbestos, is a trade name for the amphiboles belonging to the Cummingtonite - Grunerite solid solution series,
commonly from africa. It is found most frequently as a fire retardant in thermal insulation products and ceiling
tiles.
Blue Asbestos
Crocidolite asbestosis is an amphibole found primarily in southern Africa, but also in Australia. It is the fibrous
form of the amphibole.
All forms of asbestos are fibrillar in that they are composed of fibres with a width less than 1 micrometer that occur
in bundles and have very long lengths. Asbestos with particularly fine fibres is also referred to as "amianthus".
Other Asbestos Materials
Other regulated asbestos minerals, such as tremolite, actinolite (or smaragdite),and anthophyllite are less commonly
used industrially but can still be found in a variety of construction materials and insulation materials and have been reported
in the past to occur in a few products.
Amphibole Asbestos Group
Five types of asbestos are found in the amphibole group: amosite , crocidolite, anthophyllite, tremolite, and actinolite.
Amosite asbestos is the second most common type to be found in buildings, its uses include ceiling and wall panels,
fire break bulkheads, moldings to safety glass, as linings to fire doors, cement sheets and pipes for construction and
Asbestos Insulating Board (AIB).
The use of all types of asbestos in the amphibole group has now been banned.
