Evaluation of a hyperspectral scanner allowing for deterioration status assessment of asbestos-cement roofing sheets

Aim of this study is the identification of the hyperspectral scanner operational characteristics allowing for asbestos cement (AC) roofing sheets deterioration status assessment that is related to the asbestos fibers abundance. At this purpose we made laboratory measurements on AC samples with different deterioration status collected in two industrial areas in Italy. The asbestos occurrence in the AC samples was recognized using XRD and FTIR instruments and the abundance of surfacing asbestos fibers was performed by using a high resolution scanner (SEM). The samples optical characteristics and the directional effects that can affect the AC samples were analyzed using a portable field spectrometer (ASD). The results of the ASD measurements (i.e. band-depth ratio of the continuum removed calculated for the asbestos diagnostic band at 2.32?m) were related to the relative percentage of surfacing asbestos fibers (i.e. the AC deterioration status). Since laboratory measurements confirmed that optical measurements are sensitive to variations in asbestos fiber abundance, detection limit analysis was used for defining the requirements (signal-to-noise ratio, band FWHM, and sampling range) of an optimal hyperspectral sensor most suitable for detecting the diagnostic asbestos absorption features.