High-temperature structure formation in cement depending on curing time

Abstract

The paper presents a comprehensive study of the quantitative phase composition of Portland cement using the Rietveld refinement technique, a model description of its phases depending on the curing time (0–43 h) at isothermal temperature of 50 °C. The diffraction patterns of Portland cement demonstrate a large amount of crystalline component which is determined by the contribution of H6O30Si6Ca18 and O16Si4Ca8 clinker phases to the intensity. We consider the presence of hydrogen atoms in crystal lattices of H6O30Si6Ca18 and O16Si4Ca8 phases. It is shown alite phase is most of all involved in the hydration process the amount of which significantly reduces during this period, and the dissolution of O16Si4Ca8 phase occurs less intensively due to the higher atomic-binding energy in the crystal lattice. The energy-intensity of dissolution of O16Si4Ca8 surface atoms is higher than that of H6O30Si6Ca18 atoms in the crystal lattice. A comprehensive study of the quantitative phase composition of Portland cement shows that the bulk structures of clinker phases are not involved in the process of hydration. Experiments demonstrate that the crystal lattices of these phases are highly stable, and their binding energy tends to increase with the rise in curing time. The atomic-binding energy in crystal lattices of alite and larnite ranges within (187.379…187.616) and (496.764…497.016) eV, respectively. A high level of the atomic-binding energy indicates to the dissolution occurring at the interface between the solid and liquid phases. A certain atomic re-arrangement inside the crystal lattices can be accepted within the interval of stability as well as a variation of the number of atoms in unit cells.The paper presents a comprehensive study of the quantitative phase composition of Portland cement using the Rietveld refinement technique, a model description of its phases depending on the curing time (0–43 h) at isothermal temperature of 50 °C. The diffraction patterns of Portland cement demonstrate a large amount of crystalline component which is determined by the contribution of H6O30Si6Ca18 and O16Si4Ca8 clinker phases to the intensity. We consider the presence of hydrogen atoms in crystal lattices of H6O30Si6Ca18 and O16Si4Ca8 phases. It is shown alite phase is most of all involved in the hydration process the amount of which significantly reduces during this period, and the dissolution of O16Si4Ca8 phase occurs less intensively due to the higher atomic-binding energy in the crystal lattice. The energy-intensity of dissolution of O16Si4Ca8 surface atoms is higher than that of H6O30Si6Ca18 atoms in the crystal lattice. A comprehensive study of the quantitative phase composition of Portland cement sho...