WHAT IS VERMICULITE
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Vermiculite is a type of naturally occurring mineral composed of stacks of silicon based sheets that expand into accordion-like 'books' or worm-like strands when heat is applied through a process called exfoliation. These 'books' are composed of single ply sheets. Vermiculite was discovered in the Rainy Creek Mining District of Lincoln County, Montana, in 1916 The Zonolite Company and began commercial production of vermiculite in 1921.
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Vermicullite
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Does vermiculite contain asbestos?
The majority of all vermiculite insulation produced before 1990 used contaminated vermiculite from Libby. Asbestos fibers in vermiculite are too small to be seen by the naked eye. Only a trained technician using a microscope can see asbestos fibers. However, due to limitations in the methods even trained technicians cannot always determine if all vermiculite contains asbestos. Therefore, to be safe, you should assume that vermiculite insulation may be contaminated with asbestos.
Who mined vermiculite?
Vermiculite was mined in Libby, Montana, from the 1920s until the mine closed in 1990 by WR Grace. While in operation, the mine in Libby produced most of the world’s supply of vermiculite. Vermiculite has been used in building insulation, potting soil and fertilizer. Unfortunately, the vermiculite from the Libby mine contained a type of naturally-occurring asbestos called tremolite-actinolite. W.R. Grace purchased the mining operations in 1963. They greatly increased production of vermiculite which resulted in increased utilization of vermiculite in many forms of commercial products with one of the most popular being Zonolite insulation.
What is the Libby amphibole?
Asbestos is a general term used to describe several different types of fibers. In efforts to point out that our fiber is unique, many people originally used the word tremolite. This is probably not the best term either, as there is actually very little tremolite in our fiber. Therefore, the best term is Libby amphibole asbestos.
The mineralogy of Libby amphibole asbestos is very unique both chemically and structurally and the chemical composition Libby amphibole transitions between winchite, richterite, and tremolite, while also containing trace amounts of actinolite and ferro-edenite.
The mineralogy of Libby amphibole asbestos is very unique both chemically and structurally and the chemical composition Libby amphibole transitions between winchite, richterite, and tremolite, while also containing trace amounts of actinolite and ferro-edenite.
Did all vermiculite mines contaminated with asbestos?
No. Vermiculite is a naturally occurring mineral mined in the United States, Brazil, Argentina, Mexico, South Africa, Zimbabwe, Kenya, Uganda, Egypt, India, Russia, China, Japan and Australia. Vermiculite has a flaky, mica-like structure that is flat and shiny in its natural state and puffed and dull when expanded.
Is there vermiculite in my house?
Vermiculite was widely used as loose fill insulation especially in attics in domestic residences from the early 1940’s onwards. However, over the last two to three decades its use in domestic housing has declined and has usually been replaced by manmade mineral fibres such as rock wool and glass fibre (fiberglass).
Vermiculite is widely used as a beneficial additive in commercial greenhouse potting soils and in the cultivation of seedlings. It is found in many good quality packaged consumer “composts” and potting mixes available from garden centres and horticultural supply outlets.
Vermiculite is often used in passive fire protection products in high-rise construction projects to increase the fire safety of the building by preventing the premature collapse of a building, which has caught on fire; allowing for a safe evacuation and saving lives.
Vermiculite is widely used as a beneficial additive in commercial greenhouse potting soils and in the cultivation of seedlings. It is found in many good quality packaged consumer “composts” and potting mixes available from garden centres and horticultural supply outlets.
Vermiculite is often used in passive fire protection products in high-rise construction projects to increase the fire safety of the building by preventing the premature collapse of a building, which has caught on fire; allowing for a safe evacuation and saving lives.
What construction products contained vermiculite?
Building BoardsBuilding boards incorporate exfoliated vermiculite because of its low density and good insulation properties. Boards containing exfoliated vermiculite are often used as a 'core' in firedoors, to build fire barriers, to encase or construct ductwork and to protect steel building elements from the effects of cellulosic fires.
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Vermiculite in building boards
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Plasters and Exterior StuccoExfoliated vermiculite is used in both hand and spray applied general building plasters to improve coverage, ease of handling, adhesion to a wide variety of substrates, fire resistance, and resistance to chipping/cracking/shrinkage. Vermiculite can also be combined with other aggregates such as perlite to produce plasters.
Sprayed Applied Fireproofing |
Vermiculite containing exterior stucco
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Specialist Plasters Acoustic and fire protection products often use vermiculite combined with a binder such as gypsum, portland cement or more rarely an air setting clay, plus fillers and rheological aids. Structural steel fire protection products use exfoliated vermiculite to improve the application (which is generally by low pressure spray) and to impart a high degree of fire resistance. Exfoliated vermiculite is very efficient at retaining moisture, and in the event of a fire this turns to steam which has a cooling effect on the steel substrate and thus delays its temperature rise.
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Sprayed applied fireproofing containing vermiculite
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Roof and Floor Screeds and Insulating Concretes
Exfoliated vermiculite (typically the finer grades) can be added at site to portland cement and other aggregates, rheological aids and water to produce roof and floor concrete screeds or lightweight concrete which have the benefit of being lightweight and insulating. In many cases vermiculite based roof screeds are often used in conjunction with other insulation materials such as polystyrene board to form a total roofing system. Similarly finer grades of exfoliated vermiculite plus portland cement may be combined either on site or a factory premix to provide a base for swimming pool vinyl liners. These mixes are either pumped into place using a rotor stator pump or hand poured.
Loose Fill InsulationLook at the insulation in your attic without disturbing it. Expanded vermiculite is shaped like a small nugget and varies in color from silver-gold to gray-brown. The following photograph shows some typical pieces of vermiculite insulation.
There are 100's of houses in Calgary with vermiculite in the attic. Plus many cinderblock buildings have vermiculite in the cavities. |
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How can I get my house tested for asbestos and vermiculite?
If you house or building was built before 1990, Call WHS today! You can submit samples directly to us for analysis, or we can come to your house and perform a survey and identify all the asbestos containing materials in your house or workplace.