(480c) Molecular Dynamics Simulations of Fly-Ash Based Geopolymers: Conformational Changes At High Temperatures

Fernando Soto, Ancy Kunjumon, Kunal Kupwade-Patil, Erez N. Allouche and Daniela S. Mainardi

            Geopolymers are an emerging class of cementitious materials, which offer a sustainable, low energy consuming; low carbon footprint and 100% substitute to Portland cement as a cementitious binder in engineering applications. In addition, geopolymers offer an intriguing mixture of superior physical properties, extensive environmental benefits and strong prospects for commercial implementation in high performance refractory applications. The objective of this study is to gain an atomistic understanding of the structural evolution of geopolymeric gels. In particular, the ultimate goal is to develop insights as to how the molecular structure of geopolymers change with time at elevated temperatures. Density Functional Theory (DFT), Molecular Mechanics (MM) and Molecular Dynamics (MD) approaches are employed to model and simulate geopolymeric behaviors.

            In this work, two models of hydrated sodium aluminosilicates (NASH) polymers were considered. NASH models with Si:Al ratio of 1:1 and 2:1 were simulated at selected temperatures ranging from 273 K to 4273 K. The study provided information on stability, and structural and transport properties of geopolymers. Furthermore, Gibbs Free-Energy barriers were calculated to gain an in-depth knowledge of reaction rates that are essential for understanding the geopolymerization mechanism.