MOLECULAR DYNAMICS SIMULATION OF THE STRUCTURE AND PROPERTIES OF GEOPOLYMER GEL

Abstract

Fly ash captured by power plant can be mechanically grounded, activated, and then stimulated with strong alkali to produce a chemical reaction called geopolymer. Geopolymer gel is a material with a 3D network structure, which is widely used in architecture and material science. This research aims to study the structure and properties of geopolymer gel through modeling and molecular dynamics simulation. Firstly, this paper describes the molecular structure of geopolymer gel in detail using advanced modeling techniques, including the Compass force field and molecular dynamics calculation. The molecular dynamics method studied six geopolymer gel systems with different structures, and their elastic modulus, radial distribution function, and XRD patterns were deeply discussed. The results show that the elastic modulus of the geopolymer gel simulated in this study is 22.9~39.1 GPa, close to the experimental result of 47.2 GPa. The first peak positions of H-O bond, Si-O bond, Al-O bond, and O-O bond in the radial distribution function is approximately 0.097, 0.161, 0.177, and 0.263 nm, respectively, which are consistent with the experimental values. In the XRD spectrum, the dispersion peaks are distributed within the 2 θ range of 10 ° to 40 °, consistent with the distribution characteristics of the dispersion peaks observed in the experiment. The values obtained from molecular dynamics simulations align closely with those derived from experimental data, which not only verifies the validity of the structural model built but also provides a possibility for further in-depth research on the geopolymer gel system.

Keywords: Fly ash geopolymer, Gel structure model, Molecular dynamics, Molecular structure characteristics