Asbestos has been used in construction materials and equipment during extreme conditions. For example, brake pads, gloves, and clothes for thermal insulation or as reinforcement in other exposed materials.
Asbestos is a fibrous mineral containing properties including:
- Very good electrical and thermal insulation properties
- High tensile strength
- Resistance to chemicals
- Long fibers - can be woven into fabric or mats
- Large specific surface providing high absorptive capacity
Today, asbestos detection and removal is an essential task. Materials, where you can find asbestos inspection company include fireproofing, thermal insulation (e.g., pipe insulation), floor tiles, roofing tars, floor adhesives, patching and joint compounds for ceilings and walls, textiles, window sills, shoes, and brake pads.
Asbestos Detection Methods
The detection of asbestos minerals depends on the following:
- The chemical composition of the minerals
- The fact that the material is crystalline
- The appearance of the minerals, such as long fibers having a thickness greater than 3 or forming bundles (fibers split into fine fibril)
The asbestos minerals can be detected using various methods. Transmission electron microscopy (TEM) and phase contrast polarized light microscopy (PLM) are typically used. Other potential methods include infrared spectroscopy (IRS) and X-ray diffraction (XRD).
Phase Contrast Polarized Light Microscopy (PLM)
Asbestos fibers can be detected using the following:
- Appearance
- Optical properties
- Refractive index
You can identify asbestos in any material sample by using PLM. Asbestos can be detected by its appearance in a microscope. They make bundles, and the separate fibers split at the ends. The asbestos fibers should be crystalline, and their appearance should be according to the optical properties of the asbestos minerals.
Asbestos has characteristic refractive indices. However, embedding the asbestos fibers in index-matching liquids can separate the various asbestos types. Phase contrast microscopy (PCM) is also used for asbestos fiber counting.
Scanning Electron Microscopy (SEM)
Scanning electron microscopy (SEM) is used for asbestos analyses in dust and air samples. The asbestos fibers are detected using their
- Appearance
- Chemical composition
With SEM, fibers extremely fine for identification with light microscopy can be easily detected.
Analyses for asbestos fibers in dust are typically performed to assess if asbestos has been spread during asbestos removal.
Similarly, the asbestos concentration in the air is detected after its removal work to ensure that these hazardous asbestos fibers have not dispersed to the surroundings.
Transmission Electron Microscopy (Tem)
Asbestos fibers can be detected using TEM by:
- Appearance
- Chemical composition
- Crystal structure
A benefit of using TEM is that extremely fine asbestos fibers can be analyzed, and their crystal structure and chemical composition can be determined. Asbestos fibers to be analyzed using TEM require a diameter of less than 0,1 µm. TEM uses the energy dispersive X-ray detector to identify the chemical composition of the asbestos fibers. Another asbestos detector can determine a refraction spectrum reflecting its crystal structure. That way, it’s easy to separate amorphous asbestos fibers from crystalline ones since the former don’t exhibit refraction spectra.
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