Researching the Influence of the CaO/Al2O3 Ratio on Ettringite Formation and Obtaining the Structure of a Cement Paste with Special Properties

Abstract

The hypothesis of the dependence of the value of the Gibbs surface energy on the ratio of molecular masses mСаО/nAl2О3 (ΔG=f(mСаО/nAl2О3)) is confirmed, and it is proposed to determine the effectiveness of its influence on the hydration process of minerals of composite sulfoaluminate systems by means of the mineral coefficient KСА= Сm/An, where Сm/An is the Gibbs surface energy, KСmАn is the mineral coefficient of the system. This makes it possible to arrange the minerals of the CaO-Al2O3 system in the following order: СА2, СА, С12А7, С3А respectively with surface energy, kJ/mol – 24.7; 51.86; 141; 145 and later use the coefficients for researching multicomponent systems. Research on the influence of nanodisperse additives in the composition of the system (Al2O3-CaO-SO3-H2O) is aimed at managing the hydration. Formation of a strong structure is associated with the creation of a gel phase and hydroaluminates of cubic crystal system − С3АН6, as well as a stable ettringite phase. With the help of nanomodifiers, the formed blocks are freely joined in the cement matrix, which leads to a decrease in internal stresses in the not yet formed cement system. In addition, there is an assumption on doping of C3AŚH32 and C3AŚH12 crystals.