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Chemical Properties of Asbestos Chemical characteristics of Asbestos: solubility, effects of heat, acid resistance, + thermal insulation, emissivity
POST a QUESTION or COMMENT about asbestos definition, chemical, mechanical, composition, iron content, thermal & other properties
Chemical properties of asbestos: this article describes the chemical properties of asbestos in various forms, such as asbestos solubility, the affect of acids on asbestos, the effects of heat on asbestos, and related properties.
This article series describes the physical properties of asbestos including its mechanical, chemical, electrical and related properties both in pure asbestos form and when asbestos is mixed with other materials like cement or rubber. As the author points out, while this is a lenghty article, there is far more detailed information about asbestos properties, chemistry, etc.
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Chemical Properties of Asbestos
One of the more important theories concerning formation
of asbestos recognizes that the primary rock formation out
of'which asbestos mother rock emerged is of volcanic origin.
In Canada and other important asbestos areas, this green
colored mother rock is principally olivine, classified chemically
as magnesium silicate.
The pH of asbestos is generally listed as 9 to 10. When
asbestos is acid washed or subjected to other chemicals, it
can be made to behave tisfctôrily with acid curing poly
mers or resin systems
The chemical feature common to all asbestos is that they
are hydrated silicates The degree of hydration varies from
approximately one per cent in some types to as much as approximately
14 per cent in most kinds of chiysotile It generally accepted that asbestos is a metamorphic product
derived from certain types of silica-bearing minerals.
Effects of Chemicals on Asbestos
Published data showing the effect of chemicals on asbestos
are given inTable 2.9 below. it is reported that room temperature
tests were conducted for periods of 24, 192, 360, and 528 hr.
* ASTM (D577-52, Method D39, Section 10) tensile grab test.
Inasmuch as most of the fibers reached maximum solubility
after 528 hr, only this period was reported.
TABLE 2.9. SOLUBILITY OF ASBESTOS [Click to enlarge]
Per Cent Loss in Weight, Refluxing Two Hours, 25% Acid or Caustic
* Badollet, M. S., "Asbestos, A Mineral of Unparalleled Properties," Can.
Mining and Met. Bull. (1951).
Effects of Heat on Asbestos
When asbestos is exposed to heat, it loses water of crystallization.
At approximately 800°F, hornblende asbestos generally loses the greatest part of its combined water while
serpentine loses only approximately 15 per cent. Hornblende
asbestos becomes extremely brittle at 750°F.
In the case of
serpentine asbestos, flexibility remains. Table 2.10 below gives the
percentages of loss in weight versus temperatures up to
1,800°F. Test specimens were predried to remove surface
water and weighed; After heat exposure for two hours, the
asbestos was cooled at room temperature in a desiccator prior
to reweighing. If asbestos were cooled in the open room,
moisture from the air would be absorbed and weights would
differ.
When asbestos fibers are dehydrated, they change in such
properties as mechanical strength. Water content in asbestos
includes hygroscopic moisture adhering to the asbestos sur-
face and the chemically combined water of crystallization.
The content of hygroscopic moisture in asbestos has no rela
tionship to its chemical composition. It is directly related to
such an environmental condition, as degree of relative
humidity in the air. Removal of this moisture can be accom-
pushed by subjecting asbestos to a temperature of approxi35
mately 212°F. At a relative humidity of approximately
40 per cent, moisture pickup in asbestos after equilibrium
is reported to be approximately 1 per cent; at 70 per cent
relative humidity, the total pickup is 1.5 per cent; at 95
per cent relative humidity, the total pickup is 2.5 per
cent.
TABLE 2.10. EFFECT OF TEMPERATURE ON Loss IN WEIGHT
OF ASBESTOS FIBERS * [click to enlarge]
*
Can. Mining and Met. Bull. (1951). ! Iron changing in weight caused by oxidation.
The Acid Resistance of Asbestos: Acid Washed Asbestos Fiber
The acid resistance of
asbestos is important in a number of such different applications
as corrosion resistant plastic, cement equipment, and
filters. In some applications, it is desirable to remove all
metallic and foreign matter. Mechanical devices as well as
chemical, cleaning or washing processes are used.
With regard to the chemical process, the general proce-
dure is to immerse asbestos in a boiling solution of 15 to 25
per cent hydrochloric acid. One to two hour immersion is
generally sufficient. After the acid washing, the asbestos is
subjected to water rinsing. The water will remove all free
chlorine and neutralize the fiber. This process generally
produces a loss of approximately 10 per cent, by weight, of .
the original asbestos. Loss in weight is due to removal of
the metallic and foreign matter.
The acid washed fibers are
dried in order to make them useful in such other processes
as treatment with plastic or rubber resins.
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In addition to any citations in the article above, a full list is available on request.
[1] ASBESTOS HISTORY & PROPERTIES [Book online] D.V. Roasato, engineering consultant, Newton MA, Reinhold Publishing Co., NY, 1959, Library of Congress Catalog No. 59-12535. We are in process of re-publishing this interesting text. Excerpts & adaptations are found in InspectApedia.com articles on asbestos history, production & visual identification in and on buildings.
[2] "Asbestos in Plastic Compositions", A.B. Cummins, Modern Plastics [un-dated, pre 1952]
[3] "Asbestos in Your Home," Spokane County Air Pollution Control Authority, Spokane WA 509-477-4727 www.scapa.org provides a one-page image, a .pdf file drawing of a house warning of some possible sources of asbestos in the home. The sources are not ranked according to actual risk of releasing hazardous levels of airborne asbestos fibers and the list is useful but incomplete.
[4] The US EPA provides a sample list of asbestos containing products epa.gov/earth1r6/6pd/asbestos/asbmatl.htm
[5] "Characterization of asbestos exposure among
automotive mechanics servicing and handling
asbestos-containing materials", Gary Scott Dotson, University of South Florida, 1 June 2006, web search 3/9/2012 original source: scholarcommons.usf.edu/cgi/viewcontent.cgi?article=3505&context=etd [copy on file as /hazmat/Automotive_Asbestos_Exposure.pdf ].
[6] Asbestos Identification and Testing References
Asbestos Identification, Walter C.McCrone, McCrone Research Institute, Chicago, IL.1987 ISBN 0-904962-11-3. Dr. McCrone literally "wrote the book" on asbestos identification procedures which formed
the basis for current work by asbestos identification laboratories.
Stanton, .F., et al., National Bureau of Standards Special Publication 506: 143-151
Pott, F., Staub-Reinhalf Luft 38, 486-490 (1978) cited by McCrone
[6] ASBESTOS IN YOUR HOME U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
[7] Asbestos products and their history and use in various building materials such as asphalt and vinyl flooring includes discussion which draws on ASBESTOS, ITS INDUSTRIAL APPLICATIONS, ROSATO 1959, D.V. Rosato, engineering consultant, Newton, MA, Reinhold Publishing, 1959 Library of Congress Catalog Card No.: 59-12535 (out of print, text and images available at InspectAPedia.com).
[8] "Handling Asbestos-Containing roofing material - an update", Carl Good, NRCA Associate Executive Director, Professional Roofing, February 1992, p. 38-43
[9] EPA Guidance for Controlling Asbestos-Containing Materials in buildings, NIAST, National Institute on Abatement Sciences & Technology, [republishing EPA public documents] 1985 ed., Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460 Copy on file as ASBESTOS IN YOUR HOME - U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
Basic Information about Asbestos, US EPA, web search 08/17/2010, original source: http://www.epa.gov/asbestos/pubs/help.html
"Handling Asbestos-Containing roofing material - an update", Carl Good, NRCA Associate Executive Director, Professional Roofing, February 1992, p. 38-43
EPA Guidance for Controlling Asbestos-Containing Materials in buildings, NIAST, National Institute on Abatement Sciences & Technology, [republishing EPA public documents] 1985 ed., Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
EPA, ASBESTOS IN YOUR HOME [PDF] - U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
[copy on file as /hazmat/Vermiculite_US_EPA.pdf/ Current Best Practices for Vermiculite Attic Insulation - May 2003, U.S. EPA
[copy on file as] /hazmat/Vermiculite_Health_Canada.pdf] Vermiculite Insulation Containing Amphibole Asbestos - September 2009, Health Canada
Managing Asbestos in Place, How to Develop and Maintain a Building Asbestos Operations and Maintenance (O&M) Program, U.S. EPA, web search 01/20/2011, original source: http://www.epa.gov/asbestos/pubs/management_in_place.html
Asbestos Strategies, Lessons Learned about Management and Use of Asbestos: Report of Findings and Recommendations on the Use and Management of Asbestos, 16 May 2003, US EPA, web search 01/20/2011, original source: http://www.epa.gov/asbestos/pubs/asbstrategiesrptgetf.pdf prepared by the: Global Environment & Technology Foundation, 7010 Little River Turnpike, Suite. 460, Annandale VA 20003
Other US EPA Publications on asbestos: web search 01/20/2011, see http://www.epa.gov/asbestos/pubs/pubs.html
In addition to citations & references found in this article, see the research citations given at the end of the related articles found at our suggested
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: info@carsondunlop.com. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
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