Novel Selective Dyeing Method for Chrysotile Asbestos Detection in Concrete Materials

There are a tremendous number of asbestos-containing buildings without any surveys on the presence of asbestos because of the difficulty to detect asbestos in building materials simply and quickly, although a great deal of worldwide effort was put into removing asbestos of which inhalation causes serious diseases. In this study, we newly developed a simple dyeing method to detect chrysotile asbestos, the most commonly used type of asbestos, in asbestos−cement composite materials using magnesium-chelating organic dyes. As an essential process for selective dyeing of chrysotile asbestos, special pretreatment with a calcium-chelating agent was developed to prevent the dyes from reacting with calcium, which is the major component of concrete materials. Our developed selective dyeing method was shown to possess sufficient sensitivity for detecting chrysotile asbestos in an amount greater than 0.1 mass% in concrete specimens, and there was an approximately linear relationship between the area fraction of dyed spots and the mass fraction of chrysotile asbestos. Our results may provide a basis for further development of a simple on-site detection method for chrysotile asbestos in building materials and may facilitate the progress of control and removal of asbestos in the environment.