Asbestos is a naturally occurring silicate mineral which grows in veins within mesomorphic rock. There are six asbestos types, split into two categories.
The commercially used types of asbestos are Chrysotile (white), Amosite (brown) and Crocidolite (blue). Often asbestos fibres are referred to by colour, although this is not visually identifiable.
Asbestos was used for its versatility; mechanical properties and chemical, heat and electrical resistance. Asbestos is highly chemically inert; therefore it was frequently used for the externals of buildings such as roof tiles, roof ridges, rainwater products and external panels. The chemical inertness of asbestos makes it frequently found within production plants which use acids.
Uses of asbestos
Asbestos was used both as an additive and as a primary material in a number of building applications. Typical material uses were:
- Asbestos insulation board for ceiling tiles, partitions, soffits, transoms etc. They can be up to 85% asbestos and semi compressed which enables easy fibre release. Only to removed/worked on by a licensed asbestos removal contractor.
- Asbestos cements, used as roof sheets, flue pipes, guttering, roof tiles etc. Usually 10-15% white asbestos, although if pre-1955 likely to be blue asbestos.
- Lagging on pipes and calorifiers. Typically around 15% asbestos and only to removed/worked on by licensed asbestos contractors.
- Asbestos reinforced composites used as floor tiles, stair nosings, sink pads, toilets seats and cisterns. The bitumen adhesives on floor finishes can contain asbestos. These are typically low risk materials.
- Asbestos rope and cloth. Fire blankets, gaskets, cable insulation and flash guards can contain asbestos woven textiles. Fibre release depends on the material type. Typically woven Chrysotile (white) asbestos fibres.
- Sprayed coatings, up to 85% asbestos mixed with an adhesive and sprayed on to structural steel columns, beams and purlins. Sprayed coatings are a licensed material, and have a high fibre release if disturbed.