Studies of Fractal Aspects of Cement

Small angle neutron scattering can be used to reveal the fractal nature of matter. The problems of fractal aspects of the structure of cement are related to those of fractal aspects of silica aerogels. Natural cement, when mixed with water, transforms after a series of chemical reactions (in a large part) into an amorphous phase called C-S-H. It is believed that the cationic sublattice composed of CaO$\text{}_{6}$ octahedrons constitutes the C-S-H structural basis, to which the SiO$\text{}_{4}$ tetrahedral chains are attached. It is a layer structure in which the cation sublattice determines the way of SiO$\text{}_{4}$ condensation. It is natural to expect that in this way one may obtain a really amorphous substance, since some tetrahedrons may be lacking, which leads to defects. We present here the results of a small angle neutron scattering and X-ray diffraction study of several samples with the pure C-S-H phase for which during the process of chemical synthesis various ratios of molar contents of CaO and SiO$\text{}_{2}$ were used (various C/S ratios). We obtained a gradual change of fractal characteristics with the change of C/S ratio.