What is Asbestos?
Asbestos is a naturally-occurring fibrous silicate mineral found
predominantly in metamorphic rock. Asbestos minerals crystallize in narrow
veins as parallel bundles of tiny fibers. These fibers are very small, and may
remain airborne for several hours when broken-up and dispersed into the air.
Asbestos is very resistant to acids, fire, and heat. Asbestos is also known for
it's high tensile strength.
There are two categories of asbestos: serpentine and amphiboles. The serpentine
group is comprised of chrysotile, also known as
"white asbestos." Chrysotile fibers are hollow and pliable. Over 95%
of all asbestos used in the United States is the chrysotile
variety. The amphibole group is comprised of amosite
and anthophyllite, crocidolite
also known as "brown" or "blue" asbestos as well as actinolite, tremolite, and anthophyllite. Amphibole fibers are hard and straight.
How Was Asbestos Used?
Asbestosí resistance to chemicals and heat, high tensile strength, and low cost
made it a very attractive ingredient in thousands of building and thermal
insulation products. Some typical uses of asbestos include transite
pipes, floor tiles, sheet floorings, drywall, drywall texture, drywall joint
compound, insulation, automotive brakes and clutches, electric wiring
insulation, transite siding, structural fireproofing
and roof shingles.
In the late 1970ís, the U.S. began banning the use of asbestos in most building
products due to studies confirming the harmful health effects caused by
exposure to airborne asbestos. Manufacturers were allowed to deplete their
existing stocks of asbestos materials, so some asbestos products were still
being installed in buildings in the 1980's.
The last ban on manufacturing with asbestos building products was stayed by the
U.S. Supreme Court in the late 1980ís. This makes it possible for certain
building materials such as mastics, adhesives, and wall texturing to be made with
asbestos. With the advent of the North American Free Trade Agreement (NAFTA),
other asbestos-containing building products are currently being shipped into
the U.S. from Mexico and Canada.
What is Asbestos Abatement?
Asbestos abatement is the removal, repair, encapsulation, enclosure, or
clean-up of asbestos-containing materials (ACMs). Abatement is performed in
academic and non-academic buildings and utility tunnel systems to assist
departments with a planned renovation or maintenance activity, and to ensure
compliance with federal and state regulations. On some occasions, unplanned,
emergency abatement is performed to remove asbestos materials from mechanical
equipment to allow critical repairs to be performed, or to clean-up an area
contaminated by asbestos when a building system suddenly fails (e.g. roof
leaks, steam system failures).