Ettringite Strengthening at High Pressures Induced by the Densification of the Hydrogen Bond Network

• Published in: Journal of physical chemistry. C Vol. 116; no. 30; pp. 16138 - 16143
• Main Authors: Manzano, H, Ayuela, A, Telesca, A, Monteiro, P. J. M, Dolado, J. S
• Format: Journal Article
• Language: English
• Published: Columbus, OH American Chemical Society 02.08.2012
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Elasticity, elastic constants; Elasticity. Plasticity; Electron states; Exact sciences and technology; Mechanical and acoustical properties of condensed matter; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Mechanical properties of solids; Metals. Metallurgy; Methods of electronic structure calculations; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Strengthening; Ettringite; Densification; Pressure effects; Amorphization; Moisture; Elasticity; Theoretical study; Mechanical properties; Minerals; Lattice parameters; Portland cement; High pressure; Hardening; Hydrogen bonds; Low pressure; Humidity; Density functional method; Elastic properties; Bulk modulus; Crystal structure
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp301822e

Ettringite is a rare mineral with high-water content, more than half of its weight, and a relevant secondary product in Portland cement. Using density functional theory, we simulate the crystal structure and properties of ettringite under pressure. Our calculations predict a change in slope for all the lattice parameters versus pressure at about 2.5 GPa. Above such pressure, the elastic properties show a drastic increase of nearly 80% in the bulk modulus. This finding is explained in terms of a concurrent amorphization and densification of the hydrogen bond network. At low pressures, ettringite can be compressed substantially without significant repulsion in the hydrogen bond network. At high pressures, the hydrogen bonds become stiff, and their contribution to the total repulsion is then important. These changes are also supported by the evolution on the electronic density of ettringite with pressure.