Atomistic Modeling of Interactions Between Minerals and Organics in Civil Infrastructure Materials
Date
2020-03-26Metadata
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This document comprises a sum of research efforts aimed at the discovery of mechanisms of interaction between mineral (inorganic), and organic substances used or occurring in civil infrastructure materials. This endeavor involves the consideration of both physical and chemical phenomena as the driving forces of the interaction mechanisms. The scale required for such purpose magnifies the very specific chemical
composition and structure of infrastructure materials: the molecular scale, because it is the molecular scale that which captures both the physical and chemical nature of all substances composing matter.
Within the various types of civil infrastructure materials and systems, this work focuses on those used for roadway pavements: asphalts, polymers, mineral fillers, aggregates, and soil minerals. A substantial portion of the research efforts reported in this document is dedicated to the elucidation of mechanisms of interaction between asphalt molecular constituents and mineral fillers used in the mastic phase of asphalt mixtures. Specifically, one case has posed great interrogatives to many researchers due to its manifold advantages: hydrated lime. As opposed to other fillers, such as those of siliceous nature, hydrated lime has been experimentally proven to improve asphalt performance and durability and has been addressed as an “active filler” as opposed to the rest which have been named “inert fillers”. Yet, the molecular mechanism explaining such difference in behavior is still unclear. With the advance of molecular modeling tools and techniques, this work shows the first insights into the molecular nature of the interaction of hydrated lime with key molecular species present in asphalt mixtures. The superiority of the interactions of hydrated lime with asphalt moieties is both validated and quantified by the determination of the molecular free energies of interaction of each component, and the formulation of a dissociation energy value.
In the case of the polymer interaction with soil minerals it is shown how experimentally a novel formulation can be synthesized, experimentally validated, and further evaluated using atomistic modeling techniques including molecular dynamics simulations to qualitatively verify trends and behaviors with representative soil minerals such as sodium montmorillonite.
Citation
Grajales Saavedra, Javier Aurelio (2020). Atomistic Modeling of Interactions Between Minerals and Organics in Civil Infrastructure Materials. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /191649.