Researching the influence of the CaO/Al₂O₃ ratio on ettringite formation and obtaining the structure of a cement paste with special properties

¹ Prydniprovska State Academy of Civil Engineering and Architecture, Technology of Building Materials, Products and Structures Dept., 49005 Architect Oleha Petrova Str. 24-a, Dnipro, Ukraine
² Dnipro State Agrarian and Economic University, Civil Engineering, Technology of Construction and Environmental Protection Dept., 49600 Serhiya Yefremova Str. 25, Dnipro, Ukraine

^* Corresponding author: hryshko.hanna@pdaba.edu.ua

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.