Digital Image Processing and MEB (BSE) Techniques in the Identification and Quantification of Minerals Phases Present in Cement and Concrete

Abstract

AbstractThe generation processes of microscopic images in as Backscattered Scanning Electrons (BSE) are produced by complex interaction between incident electrons beam within the specimen. Different authors have correlated the energy of impact released with the mean atomic number (Z) of the phase to study, and deducing that the nature of the scattering events induced by the electron beam is strongly controlled by the Z value of them. If we compared the amount of electron backscattering with respect to response of the beam energies and so deduced a mathematical functions, for each specimen studied, and respectively by to digital images processing (based on the linear transformation of levels grey range in those energies) allows to sharpen in the discrimination and quantification of some phases in cements that, due to overlap processes, until now, could not be isolated. By means theses theoretical studios it is possible, for example, to identify interstitial cations that impinge on Z factor of phase deducing for each types of energies answer a series of mathematical functions, fitting a coefficient and across digital image techniques allows to sharpen in the discrimination and quantification of certain phases in cements that, as well, is noted in grey levels of digital image. In electron microscope have to settle down a strict work conditions (DW=10 mm, V0=20 KeV), and from a pattern specimen, found the grey level of image histogram for those working conditions, and fitting to the linear function, even if operated with BSE, the theoretic phases deduced from the EDX and the quantitative analysis of the stoichiometric formula. Given a coefficient (ç) its effective Z it's calculated; the deviation, therefore, gives the interstitial cations presence. With this tool, for example, the ettringite of gypsum is discriminates; or C-S-H products and the C3S. Once obtained the greys levels image of surface to examine and by means of threshold images process (a value of limit grey level or phase identification) he is immediate to obtain stereological relations (working with planar surfaces, which facilitate the treatment and the development of algorithms of mathematical morphology) and quantitative character phases of each phase