10. Uses of asbestos
Chrysotile was by far the most abundant asbestos form in terms of production and usage (about 93 per cent). It can be found in a wide variety of products from yarn, rope and textiles to cement, insulation boards, friction materials, gaskets and thermoplastics.
Crocidolite had a similar widespread use although the tendency was to use it in mixtures with other asbestos varieties. Amosite, because of its coarser nature, tended to find greater use in asbestos board and other rigid products. All three varieties may be found in all proportions in old laggings of pipes and boilers. Crocidolite was little used after about 1970, amosite after about 1980 and chrsyotile after about 2000
The uses of asbestos in building construction are divided into ten broad categories:
- spray coatings and lagging
- insulating board
- ropes, yarns and cloth
- millboard, paper and paper products
- asbestos cement products
- bitumen felts and coated metals
- flooring materials
- textured coatings and paints
- mastic, sealants, putties and adhesives
- reinforced plastics
Spray coatings were used for anti-condensation and acoustic control or as fire protection on structural steel. They comprised a thin layer of cement and fibre mixture applied by high-pressure spray. The main fibre type used was amosite although the other two main varieties may sometimes be found.
Laggings are found on boilers, pipes and other items of plant. These laggings may have been produced from pre-formed sections, for example on pipes, using boards or quilts or trowelled on from a thick cement mixture. These materials are sometimes known as 'monkey dung'.
Insulating boards were manufactured from cement or calcium silicate mixed with asbestos. They were produced to provide a low density, low cost fire resistant insulation and can be found in a wide variety of buildings, both commercial and domestic.
Asbestos yarns were used in the manufacture of asbestos cloth for fire protective clothing, gloves and in fire blankets. They may also have been used in gaskets or packing materials.
Asbestos millboard and papers were generally used in fairly specialist applications such as insulation of electrical equipment. They contain a high proportion of asbestos and these products are easily damaged or abraded.
The fibre cement products produced with asbestos have had widespread use. They contain about 10% asbestos, mostly chrysotile but some crocidolite or amosite were used prior to 1976. They differ from the insulating boards in their density, which is about two to three times higher.
The remaining applications, floor tiles, bitumen felts etc, have a much lower potential to release fibres and have generally not presented a great problem in use.
Figure 12 Possible locations of asbestos-containing materials in a building.
Key to Figure 12
1 Roof/external construction
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2 Internal constructionWalls/ceilings
Door
Floor
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3 Heating, ventilation & electrical equipment
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4 Other items
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Asbestos usage in equipment and appliances is divided into:
- domestic appliances, such as cookers, washing machines etc
- house goods, kitchen mats and ironing board pads
- fire blankets
- in heating systems
- DIY products
In the past there has been concern about asbestos in heating systems where damaged asbestos blocks or panels released fibres into the room. The warm air coming out of these heaters could effectively distribute the asbestos through the room.
There are helpful images of asbestos containing materials at http://www.hse.gov.uk/asbestos/gallery.htm
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