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The properties of asbestos fibers such as dimensions, thickness, strength, and related features are discussed in this article.
The ultra-fine thickness of individual asbestos fibers affect its properties, utility, and hazardous nature as explained here.
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.
Figure 2.2. View showing parallel fiber structure of asbestos vein, (Courtesy Johns-Manville-Corp.) [Click to enlarge any image]
Asbestos is generally as dense as the rock in which it occurs but
it forms masses of fibers. Specific gravity of the fibers range
from 2.5 for chrysotile to 3.3 for the other types.
The fibrous structure of asbestos is as important to its industrial value as its mineral nature. Asbestos can be subdivided
into fibers so fine that only the electron microscope
will reveal them. The finest fibers are found in chrysotile.
Its basic single fiber is a smooth cylinder approximately
A in diameter (0.00000071 in.) .
In comparison, a human
hair might have a diameter of 0.00158 in. Because of the
fine structure of the asbestos, approximately 850,000 1,400,000 fibrils are found in a linear inch of chrysotile ; however, only 630 human hairs can packed into a linear inch.
Table 2.2 below includes information comparing chrysotile asbestos fibers with other common fibers.
[You will observe that asbestos fibers are among the smallest diameter materials known - Ed.]
TABLE 2.2 COMPARISON OF DIAMETERS OF VARIOUS FIBERS
WITH ASBESTOS *
* Can. Mining and Met. Bull. (April, 1951).
Asbestos fibers have an extremely large surface area value
which is a very important property.
TABLE 2.3. COMPARISON OF THE SURFACE AREA OF VARIOUS Asbestos Fibers *
Surface Area by N2 Adsorption
Type of Fiber
* Can Mining and Met. Bull. (April, 1951) .
The surface area determination of chrysotile depends
upon the type of measuring apparatus used. For example,
if measurement of the degree of the opening of the fiber
bundles is desired, then an air permeability method is
quite satisfactory. However, if it is -desired to measure all
the available pore space between the fibers, it is necessary
to resort to a method employing gas absorption techniques.
The specific surface areas reported by nitrogen absorption
show an extreme range of values which is caused by the method of opening the fiber bundles. These values range
from 4 to 12 m2/g when carefully opened by hand, or from
30 to 50 m2/g when special mechanical equipment and chemical
dispersing agents are used.
Observations made with the electron microscope suggest
that fibers of chrysotile may be hollow. The fiber of hornblende
types is rather thicker and more solid than chrysotile,
consequently it is also less pliable and ductile. The subject
of structure of fibers has been of considerable controversy by
different basic investigators.
Low angle x-ray scattering
techniques have shown that chrysotile fibrils are hexagonally
close packed and parallel to each other, having crosssectional
diameters varying from 180A to 300A (1 Angstrom
unit equals .0000001 mm) while the amphibole fibers are
many times larger in cross section.
With regard to physical characteristics of fibers, one of
the investigators, Dr. F. L. Pundsack, states: "Although the
empirical composition of chrysotile is 3MgO2SiO2.2H20,
the true unit cell composition is best represented as
This cell has dimensions of a = 5.3A,
b = 9.2A and c = 14.6A where the "a" direction is the fiber
axis. The calculated density of this unit is 2.56 g/cc, a value
in close agreement with experimentally determined density values for chrysotile asbestos.
The exact manner in which the unit
cells of asbestos are stacked together to build up a single
fiber of chrysotile is not known, but from various lines of
experimental evidence it can be estimated that stacking in
the "b" direction probably does not exceed a width of about
Stacking in the "c" direction probably is limited to
a thickness of not more than 200A, whereas stacking in the
"a" direction may extend to a length of many millions of
Angstrom units. Because of the nature of the x-ray diffraction
pattern of chrysotile it is generally accepted that a single fiber of chrysotile does not exist as a flat lathlike
structure, but instead the fiber must be distorted in some
Efforts to account for this distortion have ranged from
depicting the single fiber as a slightly curved lath all the
way to viewing it as a completely curved structure which
forms a hollow tube. Recent evideice seems to mitigate
against a simple hollow tube structure, but as yet no com-
pletely satisfactory structure has been evolved."
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 Asbestos, its Industrial Applications, 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.
 "Asbestos in Plastic Compositions", A.B. Cummins, Modern Plastics [un-dated, pre 1952]
 "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.
 The US EPA provides a sample list of asbestos containing products epa.gov/earth1r6/6pd/asbestos/asbmatl.htm
 "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_Exposuret.pdf ].
 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
 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
 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, 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).
 "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 Copy on file as - /hazmat/Asbestos_in_Your_Home_US_EPA.pdf - 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
Copy on file as - /hazmat/Asbestos_in_Your_Home_US_EPA.pdf - 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
[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
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The HOME REFERENCE BOOK - the ENCYCLOPEDIA of HOMES, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
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