Detection of asbestos by staining with dyes for the building materials wasted at disaster and demolition sites

Abstract

Thirty-four of pieces of waste building materials were collected at disaster sites and house demolition sites. Asbestos was determined by using a stereomicroscope after staining the surface of the building materials with two different dyes, methylene blue (MB) with positive charge and erythrosine (RED-3) with negative charge. The samples were categorized to three groups: containing only asbestos like slate, asbestos and organic fibrous compounds like calcium silicate bords, and only organic fibrous compounds like gypsum bords. A mixed solution of MB and RED-3 forms nanoparticles with 150 nm in size and -34 mV surface charge, and the solution also stained selectively asbestos. As the present method stains the sample surface with the dyes and to directly observe asbestos with a stereomicroscope, asbestos was detected more clearly and sensitively than the official method (detection limit is less than 0.1%) recommended by Japanese Government. The method is easy to operate and no need to pulverize the samples, resulting no crisis of dispersion asbestos fibers into air. Thus, the method is suitable for detection of asbestos for building materials wasted at disaster and house demolition sites.