Fractal structure of C-S-H and tobermorite phases

The C-S-H I phase is the main component of the cement paste, which is a nea r-amorphous, highly porous gel. Due to high porosity of the sample in this phase we can observe a fractal nature of the volume pores distribution, sim ilar to that observed for silica aerogels. The C-S-H I phase is thermodynam ically unstable and crystallize to a tobermorite phase, forming crystal agg regates on the surface of the amorphous paste. The mixture of these two pha ses, formed in this way, have irregular volume and surface structures, both of which may exhibit the fractal nature. To study the fractal nature of th e matter the small angle neutron scattering method is frequently used. We p resent here the results of small angle neutron scattering studies supported by the X-ray diffraction and scanning electron microscope observations of several samples with the common molar C/S ratio equal to 1. Some of the sam ples were autoclaved during various: time periods to accelerate transformat ion of the C-S-H I phase to tobermorite. We observed the fractal properties of the volume structure of all samples under study. Moreover, we observed also the fractal behaviors of the surfaces of the samples which were autocl aved.