{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/115958"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/115958","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Evolution of kaolinite morphology upon calcination and dissolution","abstract":"Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-08-01","abstract_html":"Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-08-01","abstract_has_math":false,"creators":["Romero Contreras, Pablo Alfonso"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Civil Engineering","degree_department":null,"school":null,"contributors":["Garg, Nishant"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2022,"date_issued":"2022-08","date_published":"2022-08","updated_at":"2026-07-22T22:24:55Z","subjects":["Kaolinite","metakaolin","dissolution","image processing","layer thickness"],"languages":["en","eng"],"rights":["Copyright 2022 Pablo Romero Contreras"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/115958","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Garg, Nishant"]},{"key":"dc:creator","label":"Author","values":["Romero Contreras, Pablo Alfonso"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2022-08","2022-07-22"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Civil Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Kaolinite","metakaolin","dissolution","image processing","layer thickness"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en","eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2022 Pablo Romero Contreras"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/115958"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-08-01","The student, Pablo Romero Contreras, accepted the attached license on 2022-07-20 at 22:43.","The student, Pablo Romero Contreras, submitted this Thesis for approval on 2022-07-20 at 22:54.","This Thesis was approved for publication on 2022-07-22 at 09:02.","DSpace SAF Submission Ingestion Package generated from Vireo submission #18401 on 2022-11-16 at 10:56:40","The use of calcined clays as a supplementary cementitious material has been a subject of intensive research due to their high availability and their potential to be used as a low-CO2 alternative to Portland cement. Once calcined, kaolinite transforms into metakaolin, which can dissolve and react under alkaline conditions. This reactivity has been studied in terms of dissolution kinetics, but not much is known about the evolution of clay morphology upon dissolution. Here, we apply quantitative imaging approaches to statistically quantify the extent of morphological changes that occur in dissolving kaolinite and metakaolin at multiple scales. Firstly, at the micro-scale, we successfully capture in-situ exfoliation of clay particles in an alkaline solution using a novel experimental setup. We find a noticeable difference in the maximum relative Feret diameters (2.4 for kaolinite vs 1.5 for metakaolin) as well as the pattern in which these clays break apart (exfoliation for kaolinite vs disintegration for metakaolin). Secondly, at the nano-scale, we report ex-situ measurements and comparisons of individual layer thicknesses before and after dissolution. For the first time, to our knowledge, we report that kaolinite undergoes an average thinning of ~ 15 nm (from 110 nm to 95 nm) upon calcination to metakaolin, and consequently, metakaolin layers undergo an evident thinning of ~20 nm (from 95 nm to 75 nm) upon dissolution. Finally, at the nano-scale, using in-situ calcination of clay particles under TEM, we report a reduction of 2% to 5% of the area of kaolinite layers, showing that reactive surface area (in this case, the layer edges) are to be affected first. Moreover, we find that these nano-scale layers also show a reduction in their thickness, by measuring an increasing grayscale intensity of their images over time. These two main morphological changes account for the whole kaolinite layer volume, and by fitting an exponential model, it is estimated that 90% of the calcination occurs before 47 minutes. This also shows that morphological changes in kaolinite are related to its reactive surface area, and therefore, to the particle size distribution of clay powders. These new quantitative results on morphological changes in 1:1 clays upon dissolution could pave toward a fundamental understanding of clay reactivity as well as widespread usage in cementitious systems."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Evolution of kaolinite morphology upon calcination and dissolution"]}]}],"canonical_facts":{"dc:contributor":["Garg, Nishant"],"dc:creator":["Romero Contreras, Pablo Alfonso"],"dc:date":["2022-08","2022-07-22"],"dc:description":["Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-08-01","The student, Pablo Romero Contreras, accepted the attached license on 2022-07-20 at 22:43.","The student, Pablo Romero Contreras, submitted this Thesis for approval on 2022-07-20 at 22:54.","This Thesis was approved for publication on 2022-07-22 at 09:02.","DSpace SAF Submission Ingestion Package generated from Vireo submission #18401 on 2022-11-16 at 10:56:40","The use of calcined clays as a supplementary cementitious material has been a subject of intensive research due to their high availability and their potential to be used as a low-CO2 alternative to Portland cement. Once calcined, kaolinite transforms into metakaolin, which can dissolve and react under alkaline conditions. This reactivity has been studied in terms of dissolution kinetics, but not much is known about the evolution of clay morphology upon dissolution. Here, we apply quantitative imaging approaches to statistically quantify the extent of morphological changes that occur in dissolving kaolinite and metakaolin at multiple scales. Firstly, at the micro-scale, we successfully capture in-situ exfoliation of clay particles in an alkaline solution using a novel experimental setup. We find a noticeable difference in the maximum relative Feret diameters (2.4 for kaolinite vs 1.5 for metakaolin) as well as the pattern in which these clays break apart (exfoliation for kaolinite vs disintegration for metakaolin). Secondly, at the nano-scale, we report ex-situ measurements and comparisons of individual layer thicknesses before and after dissolution. For the first time, to our knowledge, we report that kaolinite undergoes an average thinning of ~ 15 nm (from 110 nm to 95 nm) upon calcination to metakaolin, and consequently, metakaolin layers undergo an evident thinning of ~20 nm (from 95 nm to 75 nm) upon dissolution. Finally, at the nano-scale, using in-situ calcination of clay particles under TEM, we report a reduction of 2% to 5% of the area of kaolinite layers, showing that reactive surface area (in this case, the layer edges) are to be affected first. Moreover, we find that these nano-scale layers also show a reduction in their thickness, by measuring an increasing grayscale intensity of their images over time. These two main morphological changes account for the whole kaolinite layer volume, and by fitting an exponential model, it is estimated that 90% of the calcination occurs before 47 minutes. This also shows that morphological changes in kaolinite are related to its reactive surface area, and therefore, to the particle size distribution of clay powders. These new quantitative results on morphological changes in 1:1 clays upon dissolution could pave toward a fundamental understanding of clay reactivity as well as widespread usage in cementitious systems."],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/115958"],"dc:language":["en","eng"],"dc:rights":["Copyright 2022 Pablo Romero Contreras"],"dc:subject":["Kaolinite","metakaolin","dissolution","image processing","layer thickness"],"dc:title":["Evolution of kaolinite morphology upon calcination and dissolution"],"dc:type":["text","Thesis"],"thesis:degree_discipline":["Civil Engineering"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["M.S."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:24:55Z"}