Asbestos is a naturally occurring fibrous crystalline mineral, found in rock formations. Three main types of asbestos have been mined in Australia, including crocidolite (blue asbestos), amosite (brown asbestos) and chrysotile (white asbestos).
After mining, the mineral was further processed by breaking down clumps of fibres into groups of loose fibres. It was mixed with other materials to produce a variety of products.
Asbestos cement was produced by mixing asbestos fibres with Portland cement and water. The asbestos fibre was added as reinforcement, to increase the strength of the product. Asbestos cement products typically contain 10-15 percent asbestos fibre by weight.
Generally, a person cannot determine whether a material contains asbestos simply by looking at it. Careful visual examination and the use of a microscope is the only way to verify the presence of asbestos. If in doubt, treat suspect material as though it does contain asbestos just to be on the safe side. In its raw form asbestos is well known to cause health effects in humans.
Generally, undisturbed asbestos cement products do not pose a health risk, as the fibres are bound together in a solid cement matrix. However, if the material is damaged or disturbed, fibres may be released into the air. The use of power tools for cutting, drilling, grinding, sanding or sawing the material can release a significant number of fibres. The use of high-pressure water blasters to clean the material prior to painting can also release large numbers of fibres so it is important to never perform these activities.
In most cases, the presence of asbestos cement building materials in a home (i.e a dividing fence) is no cause for alarm. If the materials are in good condition and are not disturbed, they do not present a health hazard. Disturbing the material (e.g by removal) may create a health hazard where none previously existed.
Special precautions must be taken when renovating buildings containing asbestos cement products, to prevent fibres entering the atmosphere. As far as practicable, asbestos cement material must not be broken, abraded or otherwise disturbed.
If it is necessary to cut holes in asbestos cement material, only non-powered hand tools may be used, or power tools that incorporate dust suppression or dust extraction equipment attachments that are specifically designed to collect asbestos fibres.
The material should be kept wet, or other practical measures taken to keep the creation of airborne fibres to a minimum.
Suitable personal protective equipment should be worn including:
If significant cutting or abrasion of the material is required, the asbestos cement material should be removed, and replaced with non-asbestos materials. If in doubt, seek advice from a building consultant.
All work performed by contractors must comply with the requirements of Worksafe (Department of Consumer and Employment Protection) and the Health (Asbestos) Regulations 1992. Details of these requirements can be obtained from the WorkSafe Division of the Department of Consumer & Employment Protection.
Special precautions must be taken when removing asbestos cement products, this is why you should seek the services of an asbestos removal contractor and as a last resort choose to remove the material yourself. If you choose to remove the material yourself, you are required to comply with the Health (Asbestos) Regulations 1992 by taking the following precautions:
When removing asbestos cement fence sheeting, it is important to ensure that all of the material is removed, including the below ground section. Dig a trench around the fence, making sure you do not dig into the fence and break up the material. Remove the entire sheet, wrap it in labelled polythene sheeting, and dispose of promptly.
For further information download Removing Absestos brochure.
Asbestos cement roofs should be regularly maintained using the following procedures:
You must take all reasonable measures to ensure asbestos fibres are not released into the air. Reasonable measures include the following;