Multi-modal characterization of cements and irradiated granites

In the evolving landscape of scientific exploration, multimodal imaging has emerged as a pivotal technique for comprehensively characterizing complex materials. Despite its potential, current methodologies face limitations in performing a holistic physicochemical and chemomechanical characterization of individual phases, especially when distinction between polymorphs is challenging. To address these gaps, this dissertation introduces an innovative Raman imaging protocol within the multimodal framework. This protocol, incorporating an auto-focusing Z-imaging feature, enables direct polymorph fingerprinting in unpolished samples and offers a new methodology for generating high-fidelity phase images applicable to any multi-phase, heterogeneous system. This dissertation investigates the applicability of the developed protocol on components of concrete, ranging from aggregates to cement. Firstly, applying this protocol to static systems like granites, definitive phase images were obtained, which were used to quantify all present minerals, uniquely distinguish polymorphs, and clearly demarcate mineral transition regions with a < 0.3–2 µm spatial resolution. Moreover, the generated Raman and EDS images of minerals had a high level of agreement (R2 > 0.97) proving that accurate phase imaging can be done on any rock specimen using the proposed methodology. Secondly, when examining other static systems such as anhydrous cements, Raman imaging was used as a complement to X-ray Diffraction (XRD) and optical microscopy in investigating Portland cements, providing highly accurate phase quantification (coefficient of determination, R2 > 0.98) of both major and minor phases in a wide range of 11 unique anhydrous cements with a total mean deviation of less than 2%. This protocol was additionally used to determine phase-specific particle size distributions and shape characteristics, providing a holistic understanding of the physical and chemical characteristics within anhydrous cements. These PSDs provided unique insights into the physical characteristics of nearly 12 unique phases across a diverse range of 10 commercial powdered cements, with the four principal phases exhibiting unique D50 values (e.g. alite: 21.6 µm, belite: 14.5 µm). A composition-size quotient parameter (CSQ) is introduced, enhancing predictive capabilities for critical performance indicators like the 72-hour cumulative heat upon hydration (R2 = 0.86). In dynamic systems, this study assesses irradiation damage in aggregates, integrating Raman imaging with various techniques, including laser profilometry, SEM, nanoindentation, and TEM. This comprehensive approach achieves a nuanced understanding of the dynamic changes induced by irradiation, particularly in silicates within concrete aggregates. Upon exposure to 10 MeV, specifically 1016 ions/cm2 Si2+ radiation, distinct mineral-specific responses were quantified (e.g. quartz undergoes a volumetric expansion of 14.8%, albite 6.8%, etc.). Utilizing Si2+ ion radiation as a surrogate for emulating neutron radiation damage, reported mineral-specific responses contribute to a comprehensive evaluation of expansions comparable to neutron radiation equivalents (R2 = 0.86, RMSE = 1.29% for 10 MeV Si2+), enhancing precision in accurately assessing radiation damage and establishing a robust framework for tackling dynamic systems through diverse imaging modalities. Collectively, this study highlights the benefits of integrating multimodal imaging, emphasizing the utility of novel Raman imaging protocol. Introducing this advanced approach addresses gaps in mineral characterization methodologies, providing a more comprehensive understanding of materials, including Portland cements and the assessment of radiation damage in concrete components of aging nuclear power plants. Beyond advancing scientific capabilities, this work opens avenues for continued exploration in the realm of multimodal imaging and material.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Civil Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2024

Author dc:creator

• Polavaram, Krishna Chaitanya

Contributors dc:contributor

• Garg, Nishant
• Popovics, John S.
• Espinosa-Marzal, Rosa M.
• Le Pape, Yann M.

• Phase-specific
• Hydration
• Irradiation Damage
• Multi-modal Imaging
• Cement
• Granite
• Raman Imaging

Statement dc:rights

• Copyright 2024 Krishna Chaitanya Polavaram

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/124633

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F124633