Aqueous reactivity of glassy industrial byproducts in alternative cementitious systems
Author(s)
Uvegi, Hugo Jake.
Download1227031961-MIT.pdf (40.80Mb)
Other Contributors
Massachusetts Institute of Technology. Department of Materials Science and Engineering.
Advisor
Elsa A. Olivetti.
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Show full item recordAbstract
Alkali-activated, geopolymeric, and other novel binders offer an opportunity to curb the carbon footprint associated with ordinary Portland cement (OPC). CO₂ emissions inherent to source-material processing (i.e., firing of limestone at 1450 °C) and annual OPC production volumes of 4.1 billion metric tons cause an estimated 5-11% of global annual greenhouse gas (GHG) emissions. Material substitution with lower-footprint resources is therefore necessary for GHG impact mitigation. Glassy silica-, alumina-, lime-, and/or alkali-rich industrial byproducts (IBs) exhibit the properties necessary to achieve emissions reductions while preserving final product attributes expected of cementitious binders. Research and industry have both focused primarily on metakaolin and IBs such as blast furnace slag and coal fly ash as supplementary and alternative cementitious precursors. Given projected limitations in such IB supply, it is imperative that we efficiently expand the materials search to other useful precursor candidates. This thesis focuses on chemical characterization and kinetic reactivity analysis of lesser-studied glassy materials through a combined experimental-computational approach, resulting in (1) physicochemical drivers for material aqueous reactivity and (2) a framework for evaluating new materials. First, I describe laboratory experiments involving reaction of a siliceous mixed-feedstock Indian biomass ash in aqueous sodium hydroxide solutions with selectively present lime and alumina sources. These experiments respectively yield tobermoritic calcium silicate hydrate products (Ca/Si ~~ 0.6-1) and semi-crystalline zeolite / geopolymer products (Si/Al ~~ 1); shown compositional ratios are known to be relevant to final material properties. Through this work, I demonstrate a novel approach to calculating reaction product composition using spectroscopic solution analysis of dissolution / precipitation experiments. Subsequently, I describe computational efforts to mine literature-reported data for potential precursor materials. This results in a database of material compositional and physical property data represented by a SiO₂-Al₂O₃- CaO ternary diagram. Finally, I employ supervised and semi-supervised computational models, which confirm log-linear relationships between glass dissolution rates (i.e., log₁₀(rate)) and pH, inverse temperature (1/K), and glass connectivity (i.e. non-bridging oxygens per tetrahedron). While less interpretable, black-box models are observed to be more robust to the presence of additional features. Throughout the research program, reactivity is understood via material dissolution in aqueous solutions.
Description
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2020 Cataloged from student-submitted PDF of thesis. Includes bibliographical references (pages 177-203).
Date issued
2020Department
Massachusetts Institute of Technology. Department of Materials Science and EngineeringPublisher
Massachusetts Institute of Technology
Keywords
Materials Science and Engineering.