Mechano-Carbonation of Portland Cement Paste: Simultaneous Milling and Aqueous Carbonation to Accelerate Carbonation Process

Mechano-Carbonation of Portland Cement Paste: Simultaneous Milling and Aqueous Carbonation to Accelerate Carbonation Process | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Mechano-Carbonation of Portland Cement Paste: Simultaneous Milling and Aqueous Carbonation to Accelerate Carbonation Process Jonathan Smith, Kiersten Williams, Juan Pablo Gevaudan This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9418583/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 5 You are reading this latest preprint version Abstract Conventional aqueous carbonation of ordinary portland cement (OPC) waste sequesters CO₂ as stable calcium carbonate while liberating pozzolanic silica gel, yet produces high specific surface areas (SSA, 50–63 m²/g) that exacerbate rheological challenges. This study investigates the influence of high-energy milling in aqueous environments with CO₂, a process named mechano-carbonation, to address these challenges. Findings show a pH-governed biphasic mechanism, where active calcium carbonate precipitation ceased within 20 minutes as the pH stabilized at 6.54–6.8, just above the first dissociation of carbonic acid (pKa = 6.35). Mechanical fragmentation of nascent silica gel followed by shrinkage and reaggregation (agglomeration) produces compact structures with lower surface area than undisturbed gel. The innovative process achieved a 91.2% degree of carbonation (DOC), 14.1–17.6%, higher than conventional aqueous carbonation methods which require processing times an order of magnitude longer. A novel finding of this study is that concurrent milling decoupled SSA from carbonation degree through mechanical fragmentation and reaggregation of nascent silica gel combined within a breakage–re-agglomeration equilibrium. Results show a 54–63% lower SSA than conventional aqueous carbonation despite higher DOC. ASTM C1897 results show an increased reactivity of 133 J/gSCM, yielding 2.8–5.9 fold higher reactivity per unit SSA than conventional aqueous carbonation methods. At 15 wt.% cement replacement, typical of portland cement Type 1L formulations, static yield stress increased by 122% (27.4 to 60.6 Pa) in comparison to limestone cement replacements. However, the maximum packing fraction showed minimal differences, indicating good workability and higher compressive strengths at 28 days. Thus, this study demonstrates mechano-carbonation as a viable processing method to produce reactive supplementary cementitious materials with controlled SSA, enabling direct substitution for limestone in Type 1L portland cement formulations at 15% replacement with superior 28-day compressive strength. Physical sciences/Chemistry Physical sciences/Engineering Earth and environmental sciences/Environmental sciences Physical sciences/Materials science Portland Cement Carbonation Compressive Stength Agglomeration Pozzolanic Activitiy Full Text Additional Declarations No competing interests reported. Supplementary Files SmithetalScientificReportsSI2026.docx Cite Share Download PDF Status: Under Review Version 1 posted Reviewers invited by journal 24 Apr, 2026 Editor invited by journal 23 Apr, 2026 Editor assigned by journal 15 Apr, 2026 Submission checks completed at journal 15 Apr, 2026 First submitted to journal 14 Apr, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9418583","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":633832568,"identity":"51cf2499-6250-4895-8d4e-af415538f907","order_by":0,"name":"Jonathan Smith","email":"","orcid":"","institution":"Pennsylvania State University","correspondingAuthor":false,"prefix":"","firstName":"Jonathan","middleName":"","lastName":"Smith","suffix":""},{"id":633832569,"identity":"dd1e12d7-bc14-419a-9413-cdee0705d039","order_by":1,"name":"Kiersten Williams","email":"","orcid":"","institution":"Pennsylvania State University","correspondingAuthor":false,"prefix":"","firstName":"Kiersten","middleName":"","lastName":"Williams","suffix":""},{"id":633832571,"identity":"0d60b4b2-3a49-4a70-b0bb-5d425a8b99ce","order_by":2,"name":"Juan Pablo Gevaudan","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA5ElEQVRIiWNgGAWjYBACxgYY6wAD4wMIK4F4LcwGRGlBgAMMbBJEaWGe3cD84mObXWLf8bPHqgv+HGbgZ88xwO+wOQfYLGe2JSfOPJOXdntm22EGyZ43BLTMSGAz5jnDnLjhQI7Zbd6GwwwGNwjZAtLy50x94obzb8yKeYAOsydCC/NjhorDiRtu5Jgx87ABbZEg6JeDbYw9FceNZ954Yyw9sy2dR+LMswK8WgxnNx/+8MOgWrbvfI7h54I/1nL87ckb8GuZwdgmAeMwAzEPXuUgIC/BwPwBWcsoGAWjYBSMAgwAAHFMTGVUCyQOAAAAAElFTkSuQmCC","orcid":"","institution":"Pennsylvania State University","correspondingAuthor":true,"prefix":"","firstName":"Juan","middleName":"Pablo","lastName":"Gevaudan","suffix":""}],"badges":[],"createdAt":"2026-04-14 17:53:29","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9418583/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9418583/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108803973,"identity":"f55cb3a3-feed-4c87-94f9-d0bdf09fd9fe","added_by":"auto","created_at":"2026-05-08 15:13:08","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":772974,"visible":true,"origin":"","legend":"","description":"","filename":"SmithetalScientificReports2026.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9418583/v1_covered_5061c8d1-e65d-4edf-8b2a-7274e98a1009.pdf"},{"id":108526849,"identity":"5d086f31-2eb5-4ceb-bbde-f610f8dba2b5","added_by":"auto","created_at":"2026-05-05 15:16:44","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":32473,"visible":true,"origin":"","legend":"","description":"","filename":"SmithetalScientificReportsSI2026.docx","url":"https://assets-eu.researchsquare.com/files/rs-9418583/v1/0fda6ffd8e166dc1da8c934d.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Mechano-Carbonation of Portland Cement Paste: Simultaneous Milling and Aqueous Carbonation to Accelerate Carbonation Process","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Portland Cement, Carbonation, Compressive Stength, Agglomeration, Pozzolanic Activitiy","lastPublishedDoi":"10.21203/rs.3.rs-9418583/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9418583/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eConventional aqueous carbonation of ordinary portland cement (OPC) waste sequesters CO₂ as stable calcium carbonate while liberating pozzolanic silica gel, yet produces high specific surface areas (SSA, 50\u0026ndash;63 m\u0026sup2;/g) that exacerbate rheological challenges. This study investigates the influence of high-energy milling in aqueous environments with CO₂, a process named mechano-carbonation, to address these challenges. Findings show a pH-governed biphasic mechanism, where active calcium carbonate precipitation ceased within 20 minutes as the pH stabilized at 6.54\u0026ndash;6.8, just above the first dissociation of carbonic acid (pKa\u0026thinsp;=\u0026thinsp;6.35). Mechanical fragmentation of nascent silica gel followed by shrinkage and reaggregation (agglomeration) produces compact structures with lower surface area than undisturbed gel. The innovative process achieved a 91.2% degree of carbonation (DOC), 14.1\u0026ndash;17.6%, higher than conventional aqueous carbonation methods which require processing times an order of magnitude longer. 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