The Use Of Backscattered Electron Microscopy And Image Analysis To Study The Porosity Of Cement Paste

In backscattered electron images of polished sections of cement paste pores can be identified down to a size of about 0.05 microns. Moreover, the contrast between pores and the solid phases is sufficient to allow the pores to be distinguished and quantified by an image analyser. There is a good correlation between measures of porosity obtained by this technique and those obtained by methanol absorbtion methods despite the lower limit to resolution.The bse method can also be used to study the distribution of the porosity in space. However, as only two dimensional sections can be examined, there are difficulties in determining the connectivity by this method. The possibility of using serial section reconstruction is examined and discussed.Despite the difficulty in relating two dimensional characterisation to three dimensional properties, several techniques have been used with some success for sandstones. Results from these techniques for cement paste are presented and discussed.