Asbestos
Asbestos was extensively used as a building material in the UK from the 1950s through to the mid-1980s. It was used for a variety of purposes and was ideal for fireproofing and insulation. Any building built before 2000 (houses, factories, offices, schools, hospitals etc) can contain asbestos. Asbestos materials in good condition are safe unless asbestos fibres become airborne, which happens when materials are damaged.
What is asbestos and where is it found?
asbestos is a naturally ocurring mineral which appears in three different forms; Chrysotile (white), Amosite (brown) and Crocidolite (blue).
Chrysotile, white asbestos, is a member of the Serpentine group, so-named because the fibre is curly. Chrysotile fibres are the most flexible of all asbestos fibres and account for approximately 95% of all the asbestos found in many countries. The fibres can withstand the fiercest heat and have a high resistance to alkaline attack but are so soft and flexible that they can be spun and woven as easily as cotton. Having considerable tensile strength they are also resistant to heat and are excellent thermal, electrical and acoustic insulators. Like the other forms of asbestos, chrysotile can absorb organic materials such as resins and polymers and can be used to strengthen particulates such as cement.
Amosite, or brown asbestos, is, like crocidolite, a member of the Amphibole group and consists of straight, brittle fibres that are light grey to pale brown and are the most commonly used in thermal system insulation. The harsh, spiky fibres have good tensile strength and resistance to heat. Amosite was used for anti-condensation and acoustic purposes; on structural steel for fire protection, preformed thermal insulation, pipes, slabs and moulded pipe fitting covers. It was also used widely in the manufacture of insulation boards.
Crocidolite, known as blue asbestos because it often ranges in colour from slate grey to a very deep blue, has fibres which are somewhat brittle but are generally flexible enough to bend beyond 90 degrees before breaking (though not nearly as flexible as chrysotile). The needle-like fibres are the strongest of all asbestos fibres and have a high resistance to acids. Crocidolite was used in yarn and rope lagging and preformed thermal and sprayed insulation. It is known to be the most lethal of all the asbestos types.
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