Before 1980, asbestos was a common building material and though rare, it is still present in a few buildings post-1980. Asbestos is a hazardous fibrous material that can lead to respiratory problems and other chronic diseases years after exposure. For this reason, homeowners or any persons removing asbestos or demolishing a home that potentially contains asbestos should adhere to specific safety procedures and state regulations. Before any removal commences, however, testing has to be done to ascertain the presence of asbestos. Below are some various methods employed to determine the presence of asbestos in bulk building materials.
The stereomicroscopic analysis involves a preliminary examination of an adequate sample volume. This technique enables the examiner to determine the homogeneity and fibre identification of asbestos. The stereomicroscopic examination cannot be used on its own and must incorporate other identification techniques.
Polarized Light Microscopy (PLM)
After the preliminary stage of a stereomicroscopic analysis, the PLM technique is employed to positively identify the fibres and determine their optical constituents. The principles of optical mineralogy enable a light microscope to observe the optical characteristics of the sample. This is aimed at determining the morphology, colour and crystallographic orientations of the sample. While PLM is the primary technique used for asbestos determination, its visual limitations are a function of the fibre size, sample preparation and distribution.
Most bulk building components can be isolated using solvents or acid washing. Removing the binder components leaves a residue of asbestos. Gravimetry is not an identification technique that can be used on its own and stereomicroscopy and PLM have to be conducted prior. The precision and accuracy of this technique are improved by taking multiple subsamples and repeating the procedure.
X-Ray Powder Diffraction (XRD)
The principles of x-ray powder diffraction dictate that a solid crystalline material diffracts monochromatic x-rays in a distinct pattern revealing the crystallines contained. Unlike PLM however, XRD cannot determine the crystal morphology but is a very reliable method in identifying asbestiform in building materials when used in combination with other techniques. The accuracy of this technique is also determined by the size distribution, sample materials and preferred orientation.
Analytical Electron Microscopy (AEM)
The Analytical Electron Microscopy (AEM) technique applies to building materials that contain a lot of binding materials. This method applies to both friable and non-friable materials and particularly applies to binding material that cannot be analysed by PLM techniques.
For more information, contact an asbestos disposal service.