Dissertations / Theses on the topic 'Tricalcium silicates'
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Begarin, Farid. "Etude de paramètres endogènes et exogènes au ciment Portland ordinaire influençant l'hydratation de sa phase principale : le silicate tricalcique." Phd thesis, Université de Bourgogne, 2012. http://tel.archives-ouvertes.fr/tel-00845948.
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Ce travail consacré à l'étude des différents paramètres influençant l'hydratation de la phase silicate principale du Ciment Portland Ordinaire (OPC) a été réalisé au Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB). Cette étude s'inscrit dans le cadre du projet " Crystal Growth Control " initié par BASF dans le but de contrôler et de prévoir le mieux possible l'hydratation du Ciment Portland Ordinaire. La dissolution de l'alite, comme celle du C3S pur, est rapide dans l'eau pure. La vitesse diminue avec l'écart à l'équilibre et la concentration en ions aluminates en solution. On observe également une adsorption sur la surface de l'alite de l'aluminium libéré par la dissolution. La germination et la croissance des C-S-H a été étudié d'une part, en présence d'aluminates en solution et d'autre part en présence de sels inorganiques connus pour être des accélérateurs de l'hydratation du ciment Portland Ordinaire. La présence d'aluminium ne modifie pas la germination initiale des C-S-H mais semble participer directement à l'origine de la période dormante du ciment. L'hydratation du C3S dans des solutions salines conduit à former pendant la germination initiale d'autant plus de C-S-H que la solution est concentrée. De plus la morphologie des germes est modifiée. Chaque germe doit contenir plus de matière en occupant moins de surface. La simulation de l'ensemble de la courbe d'avancement de l'hydratation observée dans les solutions de sels de nitrates et d'halogénures de calcium, sodium et potassium à l'aide du modèle de croissance par agrégation de particules cubiques confirme l'anisotropie au cours de la croissance des germes. La vitesse de croissance des C-S-H perpendiculairement à la surface des grains augmente avec la concentration et l'effet est très dépendant de la nature de l'anion. Ce comportement est à rapprocher des séries d'Hofmeister
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Queiroz, Marcela Borsatto. "Physicochemical and biological properties of tricalcium silicate-based reparative materials with alternative radiopacifiers and Biosilicate /." Araraquara, 2018. http://hdl.handle.net/11449/153908.
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Orientador: Mário Tanomaru FilhoAbstract: Tricalcium silicate cements associated with radiopacifiers are used as repair materials. Publication 1: Evaluation of tricalcium silicate-based cements (TCS) associated with zirconium oxide (ZrO2), calcium tungstate (CaWO4) or niobium oxide (Nb2O5) radiopacifiers compared to MTA Repair HP (MTA HP). Publication 2: Evaluation of tricalcium silicate-based cements (TCS) associated with zirconium oxide (ZrO2) radiopacifier with 10% or 20% of Biosilicate (TCS ZrO2 + 10% Biosilicate and TCS ZrO2 + 20% Biosilicate) compared to Biodentine. Setting Time (ST) and radiopacity were evaluated based on ISO 6876/2002 standard. Solubility was evaluated according to the method proposed by Carvalho-Júnior et al. (2007) modified. pH was measured at 3, 12 and 24 hours and 7, 14 and 21 days after immersion in distilled water. Cellular cytotoxicity and bioactivity were evaluated by methyltetrazolium (MTT), neutral red (NR), alkaline phosphatase (ALP), alizarin red (ARS) and real time PCR (qPCR) (Publication 1) assays in different periods of contact with eluates of the materials in Saos-2 cells. Antibacterial activity was evaluated by direct contact on Enterococcus faecalis in the planktonic form. For the physico-chemical and ARS tests, the data were submitted to ANOVA and Tukey tests; for MTT, NR and ALP tests the data were analyzed by the Two-Way ANOVA and Bonferroni tests; the antibacterial activity, were submitted to Kruskall-Wallis and Dunn tests (α = 0.05). Publication 1: TCS + CaWO4 presented... (Complete abstract click electronic access below)
Resumo: Cimentos de silicato tricálcico com radiopacificadores são utilizados como materiais reparadores. Publicação 1: Avaliação de cimento à base de silicato tricálcico (STC) associado aos radiopacificadores óxido de zircônio (ZrO2), tungstato de cálcio (CaWO4) ou óxido de nióbio (Nb2O5) em comparação ao MTA Repair HP (MTA HP). Publicação 2: Avaliação de material à base de silicato tricálcico (STC) e radiopacificador óxido de zircônio (ZrO2) e 10% ou 20% de Biosilicato (STC ZrO2 + 10% de Biosilicato e STC ZrO2 + 20% de Biosilicato) em comparação ao Biodentine. Tempo de presa e a radiopacidade foram avaliados seguindo ISO 6876/2002. A solubilidade foi avaliada de acordo com o método proposto por Carvalho-Júnior et al. (2007) modificado. pH foi avaliado 3, 12 e 24 horas, 7, 14 e 21 dias após imersão em água destilada. A citotoxidade e bioatividade celular foram avaliadas pelos testes metiltetrazólio (MTT), vermelho neutro (VN), atividade de fosfatase alcalina (ALP), ensaio de vermelho de alizarina (ARS) e PCR em tempo real (qPCR) (Publicação1), em diferentes períodos de contato com eluídos dos materiais em células Saos-2. Atividade antimicrobiana dos materiais foi avaliada por meio do teste de contato direto com Enterococcus faecalis na forma planctônica. Para os testes físicoquímicos e ARS, os dados foram submetidos aos testes ANOVA e Tukey; para os ensaios do MTT, VN e ALP e qPCR os dados foram analisados aos testes Two Way ANOVA e Bonferroni; os dados da atividade antimicrobiana f... (Resumo completo, clicar acesso eletrônico abaixo)
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Claverie, Jérôme. "Molecular dynamics investigation of the mechanical, thermal and surface properties of tricalcium silicate and its early hydration /." Ilha Solteira, 2019. http://hdl.handle.net/11449/191301.
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Orientador: João Manuel Marques CordeiroAbstract: The energetical and environmental problematic related to the cement production is a very sensitive issue. As every other field, the construction industry must go through drastic change in the design of concrete and cement-based materials. The understanding of the physical and chemical properties of the Portland cement (PC) clinker is important to improve its design. Tricalcium silicate C3S, or alite, is the main phase of PC clinker and has been largely studied since it is the first responsible for the strength development of the cement paste. On the other hand, the development of computational methods at the molecular scale has made possible the modelling of structural, dynamical and energetic properties, sometimes hardly measurable by experimental means. Such methods are relatively new in the field of cement chemistry, but have been increasingly employed over the last 15 years. In this project, density functional theory (DFT), classical molecular dynamics (MD), and ab initio molecular dynamics (AIMD) are employed towards a better understanding of mechanical, thermal, and superficial properties of monoclinic C3S, as well as C3S/water interface features. The present thesis consists of five chapters. The first chapter presents a review of the literature on the chemistry of cement, and more particularly on the hydration process modeling. The various phases which compose the Portland cement clinker are introduced, then the the different polymorphs of C3S are described, in particu... (Complete abstract click electronic access below)
Resumo: A produção de cimento envolve questões energéticas e ambientais muito relevantes. Em função disso, a indústria da construção deve sofrer mudanças radicais na concepção de concreto de materiais cimentícios. A compreensão das propriedades físicas e químicas do clínquer de cimento Portland (PC) é importante para melhorar seu design. O silicato tricálcico (C3S), ou alita, é a fase principal do clínquer de PC e tem sido amplamente estudado uma vez que é o principal responsável pelo desenvolvimento da resistência da pasta de cimento. Por outro lado, o desenvolvimento de métodos de cálculo na escala molecular possibilitou a modelagem de propriedades estruturais, dinâmicas e energéticas, às vezes difícil de medir por meios experimentais. Esses métodos são relativamente novos no campo da química do cimento, mas tem sido cada vez mais empregados nos últimos 15 anos anos. Neste trabalho, a teoria de funcional da densidade (DFT), a dinâmica molecular clássica (MD) e a dinâmica molecular ab initio (AIMD) são utilizadas para permitir uma melhor compreensão das características mecânicas, térmicas e de superfície do C3S monoclinico, bem como propriedades da interface C3S/água. Esta tese consiste em cinco capítulos: O primeiro capítulo apresenta uma revisão da literatura sobre a química dos cimento e, mais particularmente, sobre o processo de hidratação e sua modelagem. Introduzimos as diferentes fases que compõem o clínquer de cimento Portland, em seguida, a estrutura e os diferentes polimor... (Resumo completo, clicar acesso eletrônico abaixo)
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Peterson, Vanessa Kate. "Diffraction investigations of cement clinker and tricalcium silicate using Rietveld analysis /." Electronic version, 2003. http://adt.lib.uts.edu.au/public/adt-NTSM20040830.173127/index.html.
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Thesis (Ph. D.)--University of Technology, Sydney, 2003."Submited for the degree of Doctor of Philosophy, University of Technology, Sydney, Dept. of Chemistry, Materials and Forensic Sciences, August 2003" Bibliographic references: leaves 224-232.
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Whitfield, Troy T. "Effect of Tricalcium Silicate Content on Expansion in Internal Sulfate Attack." Scholar Commons, 2006. http://scholarcommons.usf.edu/etd/3802.
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The purpose of this study was to determine the cementitious parameters and placement temperature that impact internal sulfate attack in concrete. Concrete structures make up a large percentage of the infrastructure and multifamily housing. Durability is very important. Cements can be formulated to reduce the impact of external environmental exposure such as high salinity from marine environments or high sulfate levels from soils or surface waters. Concrete is also subject to internal attack such as alkali aggregate reaction, (AAR), and delayed ettringite formation, (DEF). This study focused on some of the cement chemistry issues that determine susceptibility of cement to DEF. Expansion due to DEF can weaken the concrete matrix resulting in microcracks that in some cases may progress to severe matrix cracking. The end result is loss of load carrying capacity and costly repairs.
In this study, mortar bars were made with the as received cement chemistry and using additions of sulfate, and alkalis. The bars were then heat cured at various temperatures and stored in a saturated lime solution at room temperature. Measurements were made at predetermined time intervals. The series of mixes were made to determine the effect of varying sulfate levels, heat curing temperature, and alkali content in order to isolate the effect of these constituents. The cements were selected on the basis of tricalcium aluminate, alkali content, sulfate levels, C3S levels and fineness. The results indicate that a relationship exists between the rate and level of expansion experienced by the mortar bars and cementitious parameters, namely, alkali content, sulfate content, C3S levels and heat curing temperature.
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Rastoul, Juillan Katy. "Interaction polymère associatif - ciment en milieu pâteux Adsorption - Stabilité - Rhéologie." Paris 6, 2003. http://www.theses.fr/2003PA066479.
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Mishra, Ratan K. "Simulation of Interfaces in Construction Materials: Tricalcium Silicate, Gypsum, and Organic Modifiers." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1333037184.
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Damidot, Denis. "Etude de l'hydratation du silicate tricalcique en suspensions diluées par microcalorimétrie isotherme." Dijon, 1990. http://www.theses.fr/1990DIJOS036.
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Le silicate tricalcique est le constituant principal du ciment Portland utilisé dans le béton. L’hydratation du silicate tricalcique conduit à former deux hydrates peu solubles, l'hydrosilicate de calcium et la portlandite. La cinétique de l'hydratation du silicate tricalcique a été étudiée sur des suspensions diluées et agitées par microcalorimétrie et conductimétrie. L’utilisation simultanée de ces techniques a conduit à des résultats originaux qui ont permis de mettre en évidence: 1) le début de la précipitation de l'hydrosilicate de calcium et de la portlandite; 2) l'existence de deux étapes cinétiques lors de la précipitation de l'hydrosilicate de calcium. La première est observée lorsque la solution est sous-saturée par rapport à la portlandite et la seconde lorsque la solution est sursaturée par rapport à la portlandite. Au début de chacune des étapes, la cinétique est gouvernée par la nucléation-croissance de l'hydrosilicate de calcium puis par la diffusion à travers la couche formée par ce dernier autour des grains de silicate tricalcique. Le changement de régime cinétique correspond à un taux d'avancement de la réaction différent lors des deux étapes. Ceci indique que l'hydrosilicate de calcium formé lors de la première étape est différent de celui formé lors de la seconde, bien qu'aucune différence structurale n'ait pu être établie par RMN du silicium 29 ou par diffraction des rayons X. La compréhension du processus de l'hydratation du silicate tricalcique en suspension a permis d'expliquer l'hydratation du silicate tricalcique en pâte grâce à la continuité qui a été établie entre ces deux milieux. Ainsi les hypothèses antérieures pour expliquer l'hydratation du silicate tricalcique en pâte ont pu être discutées de façon critique à la lumière de nos résultats.
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Maggion, Renaud. "Etude de l'evolution de la microtexture de pates de silicate tricalcique hydrate." Orléans, 1992. http://www.theses.fr/1992ORLE2026.
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Le silicate tricalcique, (ca#3sio#5 ou c#3s) est le constituant majeur du clinker de ciment portland. L'hydratation de cette phase conduit a la formation de portlandite et d'un gel peu cristallin, le csh qui est le principal responsable du developpement des resistances de la pate de ciment. Le developpement en continu de l'aire interfaciale accessible a l'eau a ete suivi, par rmn du deuteron, entre 0 et 160 heures apres le gachage sur des pates hydratees preparees a des rapports ponderaux d#2o/c#3s de 0,4; 0,6 et 0,8. Les resultats obtenus indiquent que la surface specifique limite (proche de 100 m#2/g) est atteinte au bout d'une soixantaine d'heures de temps d'hydratation. L'augmentation de la surface est parfaitement correlee a la precipitation acceleree des hydrates telle que l'on peut la suivre par calorimetrie. La porosite, la repartition dimensionnelle des pores, l'aire interfaciale, et la microtexture a des echelles comprises entre 2 nm et 2 m ont ete etudiees sur un lot de pates hydratees a h#2o/c#3s de 0,4 et conservees dans le lait de chaux. Le temps d'hydratation varie de 1 a 500 jours. Il apparait que l'essentiel de la structuration de la pate est realisee dans les trente a cinquante premiers jours de l'hydratation. La porosite (mesuree par intrusion de mercure et par analyse d'images), la surface specifique developpee par les hydrates et la densite sont des fonctions lineaires du taux d'hydratation. L'evolution de la texture a l'echelle micronique intervient egalement au cours de cette periode. Cependant, a plus longue echeance, la diffusion des rayons x aux petites angles indique des modifications de la microtexture a l'echelle de quelques nanometres. Cette evolution qui a lieu a taux d'hydratation constant (et egal a 1) est liee a un processus de rearrangement de l'interface qui intervient a surface accessible a l'eau constante
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Mansoutre, Sandrine. "Des suspensions concentrees aux milieux granulaires lubrifies : etude de pates de silicate tricalcique." Orléans, 2000. http://www.theses.fr/2000ORLE2014.
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Les correlations croisees entre les parametres rheologiques en cisaillement, la dilatance et les mesures de retention d'eau, ont permis d'etablir un diagramme de phase rheologique d'une pate fraiche de c 3s en fonction de la concentration depuis le regime de suspension concentree, ou le comportement est essentiellement dicte par les interactions hydrodynamiques et ou la viscosite suit la loi de krieger-dougherty, jusqu'au regime de pate granulaire, ou le comportement est domine par les contacts solides et dans lequel le materiau presente un caractere dilatant. Par extension, le seuil de cisaillement de pates cimentaires a pu etre decrit par la combinaison d'une contribution physico-chimique, qui depend du point de demande en eau de la poudre et de la force ionique de la solution interstitielle, et d'une contribution granulaire qui traduit les frottements entre les grains. L'information apportee par les mesures directes de force par afm, a permis de proposer un schema d'action d'agents modificateurs de seuil : (1) les electrolytes en solution augmentent le seuil de la pate en renforcant la cohesion entre les flocs si ces ions sont dits forts vis-a-vis de la solubilite (par exemple les nitrates) et en provoquant une transition type liquide/solide si ceux-ci sont dits intermediaires (par exemple les sulfates) ; (2) les polyelectrolytes de type poly(naphtalene sulfonate) reduisent le seuil par ecrantage des interactions entre grains dans le regime de suspension concentree et par lubrification des contacts dans le regime granulaire. La lubrification n'est effective qu'aux faibles vitesses de deformation.
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Noirfontaine, Marie-Noëlle de. "Etude structurale et cristallographie du compose majoritaire du ciment anhydre : le silicate tricalcique." Palaiseau, Ecole polytechnique, 2000. https://pastel.archives-ouvertes.fr/pastel-00003675.
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Le ciment anhydre (portland) est essentiellement constitue d'une roche artificielle, le clinker, dont le compose majoritaire est le silicate tricalcique (ca 3sio 5) souvent note c 3s avec les notations compactes de la chimie des oxydes, c = cao et s = sio 2. Le polymorphisme du c 3s, encore incompletement connu, constitue l'objet essentiel de cette these. Le silicate tricalcique cristallise sous differentes formes (rhomboedrique r, monocliniques m1, m2, m3 et tricliniques t1, t2, t3), suivant la temperature et les impuretes qu'il contient. Dans la litterature seules les structures t1, m3 et r sont connues, et montrent de grandes mailles avec un desordre orientationnel sur les tetraedres sio 4. Les etudes ponctuelles sur monocristaux ne montrent aucune relation claire entre les differents polymorphes. Reprenant en detail les resultats connus sur monocristaux, nous avons pu etablir les relations metriques et structurales entre les diverses structures. Nous avons determine des briques de base pour les polymorphes t1, m1 et m3 en donnant toutes les matrices de transformation entre les differentes mailles. Nous avons aussi introduit de nouveaux objets structuraux 1-d, 2-d et 3-d, facilitant l'interpretation des structures du c 3s. Nous avons simplifie l'interpretation du desordre orientationnel et discute de l'effet des impuretes sur la structure. Dans les clinkers industriels, les impuretes presentes stabilisent surtout les formes monocliniques m1 et m3. Nous avons determine un groupe d'espace (pc) et des modeles atomiques (surstructure et maille moyenne) pour la structure m1. Tous les modeles ont ete valides sur des echantillons de synthese (m3, m2, m1 et t1) et des clinkers industriels analyses par diffraction des rayons x avec la methode de rietveld.
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Husson, Sophie. "Etude physicochimique et mécanique des interactions ciment-fillers : Application aux mortiers." Grenoble INPG, 1991. http://tel.archives-ouvertes.fr/tel-00844622.
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Cette recherche est consacrée à l'étude des interactions entre les fillers et le ciment. Ces interactions peuvent avoir une origine physique et/ou chimique. L'utilisation d'un filler de référence, inerte chimiquement (une zircone), permet de séparer les deux effets. Nous montrons que les fillers (calcaire et zircon) de par leur activité chimique peuvent agir favorablement sur les propriétés mécaniques des pâtes pures et des mortiers. Ils ont un effet accélérateur et participent à la formation des espèces hydratées. Une partie importante de l'étude concerne l'interaction du filler calcaire avec le constituant principal du ciment, à savoir: le silicate tricalcique. L'activité chimique des fillers varie suivant leurs origines et les traitements qu'ils subissent. Le broyage peut être à l'origine de la création de défauts planaires, linéaires et ponctuels. Ceux-ci déterminent la réactivité du filler. Il existe une relation entre cette activité chimique et les propriétés mécaniques des pâtes pures. Cette corrélation nous permet de préconiser un test de sélection des fillers calcaires.
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Sowoidnich, Thomas Verfasser], and Horst-Michael [Akademischer Betreuer] [Ludwig. "A Study of Retarding Effects on Cement and Tricalcium Silicate Hydration induced by Superplasticizers / Thomas Sowoidnich ; Betreuer: Horst-Michael Ludwig." Weimar : F. A. Finger-Institut für Baustoffkunde, 2016. http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20160224-25444.
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Sowoidnich, Thomas [Verfasser], and Horst-Michael [Akademischer Betreuer] Ludwig. "A Study of Retarding Effects on Cement and Tricalcium Silicate Hydration induced by Superplasticizers / Thomas Sowoidnich ; Betreuer: Horst-Michael Ludwig." Weimar : F. A. Finger-Institut für Baustoffkunde, 2016. http://d-nb.info/1116609118/34.
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Pignat, Christian. "Simulation numérique de l'hydratation du silicate tricalcique, caractérisation de la structure poreuse et de la perméabilité /." [S.l.] : [s.n.], 2003. http://library.epfl.ch/theses/?nr=2763.
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RASSEM, RACHA. "Apport de la rmn a l'etude du mecanisme d'hydratation du silicate tricalcique, composant majoritaire du ciment portland." Paris 6, 1990. http://www.theses.fr/1990PA066287.
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Le silicate tricalcique 3ca0. Sio2 (c3s) est le constituant majoritaire du ciment ordinaire portland. Son hydratation est responsable du phenomene de prise et du developpement des resistances mecaniques. La periode dormante qui se produit dans les toutes premieres heures de l'hydratation est extremement importante car au cours de ce temps, la pate de ciment reste maleable, ce qui permet son melange aux granulats pour confectionner le beton et permettre le coffrage. Notre objectif etait de determiner la structure, la cinetique et le mecanisme reactionnel mis en jeu dans la formation des hydrosilicates de calcium (csh) en particulier durant la periode dormante. Pour ce faire, on a utilise les techniques de la rmn haute resolution en phase solide de l'isotope 29 du silicium. On a ainsi suivi l'evolution des entites silicates au cours de l'hydratation depuis les premiers instants du melange avec l'eau jusqu'a des periodes d'hydratation de quelques mois. Nos resultats sur les pates (eau/solide=0. 5) ont mis en evidence la formation d'entites hydratees monomeres de type qo des les premiers instants puis d'especes dimeres et polymeres, de type q1 et q2, et ce, des la periode dormante. L'effet retardateur de prise d'un adjuvant tel que le polynaphtalene sulfonate a ete egalement observe. L'etude de l'hydratation en suspensions diluees agitees (eau/solide=20 et 50) a conduit a l'observation des memes hydrates que leur pate. On a montre que la precipitation des csh etait independante de leur precipitation de l'hydroxyle de calcium, la portalandite, a la fin de la periode dormante
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Tran, Xuan Vinh. "Effet d'un nouveau ciment de restauration à base de silicate tricalcique sur la réparation pulpo-dentinaire : Etude In Vivo." Thesis, Paris 5, 2013. http://www.theses.fr/2013PA05T005.
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L’introduction du coiffage pulpaire dans les thérapeutiques dentaires a permis d’exploiter le potentiel de régénération de la pulpe dentaire. Le but de ce travail a été d’évaluer l’effet sur la réparation pulpo-dentinaire d’un nouveau ciment de restauration à base de silicate tricalcique dont nous avions préalablement étudié les propriétés mécaniques innovantes. Pour cela, un modèle d’effraction pulpaire sur la molaire de rat a été utilisé. Une comparaison a été réalisée entre plusieurs agents de coiffage: l’hydroxyde de calcium (Ca(OH)2), le MTA (mineraltrioxydeaggregate) et le nouveau ciment à base de silicate tricalcique. Le processus de réparation a ensuite été évalué à plusieurs temps d’un point de vue histologique,immunohistochimique et histomorphométrique. De plus, une analyse en Microscopie électronique à balayage (MEB) et une analyse par dispersion des rayons X (EDX) ont permis de qualifier l’interface entre le nouveau ciment et la dentine. Aux temps précoces, nos résultats montrent que le ciment testé et MTA induisent prolifération cellulaire et formation de foyers de minéralisation fortement marquées par l’anticorps anti-ostéopontine. A quinze jours, un pont dentinaire de réparation formé par des cellules de type odontoblastique esthomogène et dense pour le groupe des silicates tricalciques alors qu’un pont poreux est observé pour le groupe Ca (OH)2. Après un mois, le pont dentinaire est plus structuré dans les trois groupes. Dans le groupe Ca (OH)2, il est en continuité avec la dentine primaire mais apparait encore hétérogène avec des inclusions cellulaires. Dans les groupes des ciments silicates tricalciques, le pont dentinaire présente une structure tubulaire et est immunopositif pour des marqueurs caractéristiques de la dentine telle la dentinsialoproteine. L’analyse par MEB montre une bonne qualité de l’interface ciment évalué-dentine attestant ainsi de l’étanchéité de l’obturation. Ces résultats suggèrent que le ciment évalué offre un environnement optimal pour la cicatrisation de la pulpe, comparable à celle obtenue avec le MTA, le ciment de référence. Avec les limitations inhérentes à l’expérimentation animale, ce ciment de restauration biocompatible dont nous avons montré la qualité des propriétés mécaniques peut également être utilisé comme agent de coiffage pulpaire directPas de résumé en anglais
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Lecoq, Xavier. "Etude de l'hydratation à concentration contrôlée du silicate tricalcique ca#3sio#5 et des caractéristiques de ses produits de réaction." Dijon, 1993. http://www.theses.fr/1993DIJOS063.
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Un dispositif expérimental a été élaboré pour maintenir constante, tout au long de l'hydratation du silicate tricalcique (C3s) en suspension diluée, la concentration en hydroxyde de calcium de la solution. Dans le domaine de concentration en hydroxyde de calcium de la solution étudiée, entre 6 et 36 mmol/l, les courbes d'avancement traduisent toutes une période de nucléation de l'hydrosilicate de calcium (c-s-h), une période de croissance individuelle des germes de c-s-h à la surface du c#3s (période accélérée) et une période d'épaississement de la couche de c-s-h recouvrant le c#3s (période décélérée). La cinétique de l'hydratation dépend essentiellement du nombre de germes initiaux de c-s-h précipites à partir des ions accumules en solution pendant la période de dissolution pure du c#3s et du mode de croissance des c-s-h. Il a été mis en évidence la formation, a partir du c#3s, de deux c-s-h de stœchiométrie et de structure différentes. L’un précipite pour 0
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Neji, Mejdi. "Modélisation chimie mécanique et simulation numérique du comportement expansif de résines échangeuses d’ions enrobées dans une matrice cimentaire." Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10106/document.
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Les résines échangeuses d’ions (REI) sont communément utilisées dans l’industrie nucléaire pour purifier des effluents contaminés non-stockables. Les REI deviennent ainsi un déchet solide qu’il est possible de conditionner. L’une des méthodes de conditionnement consiste en un enrobage dans une matrice cimentaire. Ce procédé pose un certain nombre de questions quant à la stabilité dimensionnelle de l’enrobé. Le déchet, une fois enrobé, est en effet susceptible d’interagir chimiquement avec la matrice cimentaire ce qui peut, dans certains cas, entrainer son gonflement par le biais de pressions internes. C’est autour de cette problématique que ce travail de thèse a vu le jour avec pour objectif de développer une modélisation physico-chimique multi-échelle du composite afin d’en estimer le comportement mécanique macroscopique. Cette étude s’est exclusivement intéressée aux interactions chimie-mécaniques induites par des REI cationiques pouvant engendrer à long terme un comportement expansif de l’enrobéIon exchange resins (IER) are widely used in the nuclear industry to purge non directly storable infected effluents. IER then become a solid waste which could be stored as any classical nuclear waste. One way of conditioning consists in embedding it into a cement paste matrix. This process raises some concerns regarding the cohesiveness of the composite. Once embedded, the IER might indeed interact with the cement paste which would lead, in some cases, to the swelling of the composite. This thesis has been set up to address this potential issue, with the aim to develop a numerical tool able to predict the mechanical behavior of this kind of material. This work only focuses on the long term behavior and more specifically on the potential degradations of the cement paste /IER composite due to cationic IER
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Naber, Christoph [Verfasser], Jürgen [Akademischer Betreuer] Neubauer, and Jürgen [Gutachter] Neubauer. "Hydration kinetics of tricalcium silicate: A dataset for reaction rate calculations and nanoscale analysis employing atom probe tomography / Christoph Naber ; Gutachter: Jürgen Neubauer ; Betreuer: Jürgen Neubauer." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2019. http://d-nb.info/1176809806/34.
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Spannagel, Philippe. "Contribution à l'étude du système silicate décalcique-phosphate tricalcique et son intérêt dans la caractérisation et la valorisation de scories d'aciéries." Nancy 1, 1996. http://www.theses.fr/1996NAN10371.
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La fabrication d'acier à partir de minerai riche en hématite conduit à une production de scories pauvres en phosphore. Afin qu’elles présentent un intérêt comme amendement engrais, nous avons étudié une méthode d'enrichissement en P₂O₅ réalisable au niveau du convertisseur. L'analyse et la caractérisation approfondie d'une scorie de conversion de fonte hématite (CFH) a permis de préciser la nature des phases et de proposer une estimation de leurs teneurs respectives ; le phosphore se retrouve principalement concentré dans des phases silicophosphates calciques du système Ca₂SiO₄-Ca₃ (PO₄)₂ Nous avons montré qu’il n'existe pas de solution solide continue entre Ca₂SiO₄-Ca₃ (PO₄)₂ mais qu’il se forme trois composés définis : - Ca₃₅ (Si0₄)₁₆ (P0₄) ₂, une nouvelle phase mise en évidence/ - la Nagelschmidtite Ca₇ (SiO₄)2 (PO₄)₂ identifiée dans les scories enrichies, dont nous avons déterminé la structure cristallographique après synthèse de monocristaux et précisé les relations structurales existant entre les différents composés du système Ca₂SiO₄ - Ca₃ (PO₄)₂ ; il existe un mécanisme de substitution du silicium par le phosphore avec création de lacunes ordonnées/ - Ca₅(Si0₄) (P0₄)₂, la silicocarnotite. L'influence, à 1300°C et 1500°C, d'ajouts sodiques synthétiques ou d'origines industrielles sur la formation et les caractéristiques des composés du système Ca₂SiO₄ -Ca₃ (P0₄)₂ a ensuite été étudiée ; l'élément sodium est principalement responsable de l'augmentation des vitesses de formation des silicophosphates calciques. L'étude de mélanges scorie CFH - ajouts à haute température a montré que: - l'enrichissement en phosphate aluminocalcique joue un rôle important sur la nature, la composition, la morphologie et la répartition des phases formées/ - l'introduction d'un ajout modifie la répartition du phosphore entre les différentes phases. Ils s'avèrent, lors de l'étude de la solubilité citrique de ces produits, que ces modifications influencent le rendement en phosphore biodisponible ; la sélectivité de l'attaque citrique a été mieux comprise.
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MASSE-BARBIER, BARBIER SYLVIE. "Synthese hydrothermale d'hydrates de silicate tricalcique analyse structurale en phase solide etude comparative avec les ciments utilises pour chemiser les puits de petrole." Paris 6, 1993. http://www.theses.fr/1993PA066606.
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Dans le but de simuler l'hydratation du ciment qui sert a chemiser les puits de petrole, l'hydratation du silicate tricalcique a ete realisee dans des conditions hydrothermales entre 60 et 120c sur des durees allant de 30 minutes a 1 an. L'analyse structurale des hydrates a ete effectuee en phase solide par resonance magnetique nucleaire du silicium-29 et du proton, par microscopie electronique a balayage, par spectroscopie infra-rouge, par diffraction des rayons x et scanner x. L'etude a montre qu'une augmentation de la temperature d'hydratation entrainait une acceleration de la cinetique de 60 a 100c et un allongement des chaines silicates constitutives des hydrates. A 120c, la cinetique des reactions d'hydratation est modifiee et une phase cristalline, de la tobermorite, a ete detectee sous haute pression (200 bar)
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Garrault-Gauffinet, Sandrine. "Etude expérimentale et par simulation numérique de la cinétique de croissance et de la structure des hydrosilicates de calcium, produits d'hydratation des silicates tricalcique et dicalcique." Dijon, 1998. http://www.theses.fr/1998DIJOS057.
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Ce travail, s'inscrivant dans la continuité d'une série de travaux menés sur l'hydratation et la prise du ciment, est consacré à l'étude de la nucléation et la croissance de l'hydrosilicate de calcium (C-S-H), forme au cours de l'hydratation des silicates tricalcique (C#3S) et dicalcique (C#2S), les composants principaux du ciment portland. La cinétique d'hydratation de C#3S et C#2S est controlée par le nombre de germes initiaux précipités au tout début de l'hydratation et par le mode de croissance des hydrates, qui dépendent tous deux de la concentration en hydroxyde de calcium en solution. Ce mécanisme reste identique en présence d'autres d'électrolytes. Le nombre de germes diminue quand la concentration en hydroxyde de calcium augmente. En présence de chlorure de sodium et d'hydroxyde de potassium, il augmente. La nucléation de C-S-H suit la théorie classique de la nucléation. Au cours de l'hydratation des silicates de calcium, la nucléation des C-S-H est hétérogène. L'observation directe par microscopie à force atomique a montré que la croissance des C-S-H se fait par agrégation de particules nanométriques anisotropes latéralement et perpendiculairement à la surface du silicate anhydre. Les simulations numériques des cinétiques d'hydratation expérimentales ont montré que l'agrégation se fait de moins en moins parallèlement à la surface des grains de silicates de calcium lorsque la concentration en hydroxyde de calcium augmente en solution. En présence de chlorure de calcium la vitesse perpendiculaire à la surface des grains augmente. Cette agrégation de particules est orientée jusqu'à ce que la surface soit complètement recouverte par la couche de C-S-H. Une fois que la surface est recouverte, la formation de C-S-H est gouvernée par un régime de diffusion des réactifs à travers la couche d'hydrate et l'assemblage devient de moins en moins organisé.
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Husson, Sophie. "Étude physicochimique et mécanique des interactions ciment-fillers. Application aux mortiers." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 1991. http://tel.archives-ouvertes.fr/tel-00844622.
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Cette recherche est consacrée à l'étude des interactions entre les fillers et le ciment. Ces interactions peuvent avoir une origine physique et/ou chimique. L'utilisation d'un filler de référence, inerte chimiquement (une zircone), permet de séparer les deux effets. Nous montrons que les fillers (calcaire et zircon) de par leur activité chimique peuvent agir favorablement sur les propriétés mécaniques des pâtes pures et des mortiers. Ils ont un effet accélérateur et participent à la formation des espèces hydratées. Une partie importante de l'étude concerne l'interaction du filler calcaire avec le constituant principal du ciment, à savoir: le silicate tricalcique. L'activité chimique des fillers varie suivant leurs origines et les traitements qu'ils subissent. Le broyage peut être à l'origine de la création de défauts planaires, linéaires et ponctuels. Ceux-ci déterminent la réactivité du filler. Il existe une relation entre cette activité chimique et les propriétés mécaniques des pâtes pures. Cette corrélation nous permet de préconiser un test de sélection des fillers calcaires.
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Girod-Labianca, Caroline. "Modélisation thermodynamique des diagrammes de phases des clinkers de ciments Portland : étude de l'influence des éléments mineurs : cas du phosphore." Paris 6, 2008. http://www.theses.fr/2008PA066158.
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Le clinker, roche synthétique polyphasée, est le constituant principal des ciments Portland. Le silicate tricalcique (C3S) est la phase majoritaire du clinker anhydre et confère l’essentiel des résistances mécaniques du matériau hydraté (béton, mortier). Actuellement, les cimentiers brûlent dans leurs fours des farines animales détruites par les très hautes températures des fours. Toutefois, ces déchets introduisent du phosphore sous forme de cendres qui s’incorporent au clinker en cours de fabrication. Pour comprendre l’effet du phosphore sur les différents états chimiques du matériau, nous avons réalisé des échantillons de C3S dopés avec du P2O5 (0 à 0,9% en poids). L’étude de la structure et la microstructure de ces échantillons anhydres à montré la présence d’une phase supplémentaire de type α’-C2S enrichie en phosphore et localisée aux interfaces des grains de C3S dopés. L’hydratation de ces échantillons, suivie par microcalorimétrie, a monté un effet retardateur du phosphore sur la prise du C3S. Enfin, des essais de résistance mécanique à la compression réalisés sur des éprouvettes de mortier élaborées avec nos échantillons, ont montré que le dopage en phosphore semblait améliorer la résistance en compression du C3S. L’étude thermodynamique vise à comprendre ce qui se passe dans le four lors de la fabrication du clinker. Pour cela, nous avons développé une base de données spécifique aux phases des ciments à partir d’un bilan bibliographique des fonctions thermodynamiques utilisables pour les phases des diagrammes fondamentaux des cimentiers. Ensuite, avec le logiciel Thermo-CALC, nous avons calculé les trois diagrammes de phases pseudo-binaires Al2O3-CaO, Al2O3-SiO2, CaO-SiO2 et le diagramme de phases pseudo-ternaire Al2O3-CaO-SiO2. La comparaison des diagrammes calculés et expérimentaux nous ont permis de montrer la validité de notre base de données dans les domaines de température et de composition de la clinkérisation
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Nachbaur, Laurent. "Etude de l'influence d'électrolytes sur l'hydratation et la prise du silicate tricalcique, composant principal du ciment Portland : Caractérisation des interactions à l'origine de la prise." Dijon, 1997. http://www.theses.fr/1997DIJOS055.
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Ce travail est consacré à l'étude de l'hydratation et de la prise du silicate tricalcique, composant principal du ciment Portland, dans des solutions d'électrolytes représentatives des solutions interstitielles des pâtes de ciment pendant les premiers jours d'hydratation. On observe une continuité des phénomènes, des suspensions diluées aux pâtes et du système simple à ces systèmes plus complexes du point de vue chimique. En présence des électrolytes étudiés (hydroxydes et sulfates alcalins), le mécanisme de l'hydratation reste identique au mécanisme intervenant dans l'eau. Tous ces électrolytes sont des accélérateurs de l'hydratation. La stœchiométrie des hydrates formes (C-S-H) est déterminée par l'activité en calcium de la solution. Les ions étudiés ont des effets différents sur les caractéristiques de la double couche électrique présente autour des particules. Le calcium et le sulfate sont spécifiquement adsorbés à la surface du silicate tricalcique et du C-S-H, les alcalins sont des ions indifférents. Ces différences de comportement se retrouvent dans l'influence de ces ions sur les différentes étapes de l'hydratation. L'évolution mécanique des pâtes est caractérisée par la formation d'une structure au cours des premières minutes suivant la fin du gâchage. Cette structuration de la pâte intervient sous l'action de forces attractives qui s'opposent aux forces répulsives, dues aux interactions entre les doubles couches entourant les particules, trop faibles dans ces conditions pour s'opposer à la coagulation rapide des particules. Les forces attractives sont des forces entre surfaces, responsables également des propriétés mécaniques du solide formé après la prise. L'augmentation des résistances du matériau est due à l'augmentation des surfaces en vis à vis dans la pâte du fait de la formation des hydrates. Il s'agit d'un phénomène continu. La prise ne correspond à aucune transition structurale.
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Plassais, Arnaud. "Nanoporosité, texture et propriétés mécaniques de pâtes de ciments." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2003. http://tel.archives-ouvertes.fr/tel-00007576.
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Des silicates de calcium hydratés (C-S-H) forment le liant des matériaux cimentaires et sont responsables de sa cohésion. Mais la structure du C-S-H est encore mal décrite. Nous proposons une description de la porosité basée sur une caractérisation par la relaxation RMN des protons contenus dans les pâtes de C3S. Des courbes de relaxation longitudinale sont extraites des distributions de cinq temps de relaxation (T1). La spectroscopie RMN puis la relaxométrie permettent l'interprétation de ces T1 : le dernier correspond à la portlandite, chacun des quatre premiers correspond à une taille de pore, allant de l'interfeuillet à la plus grande dimension de l'empilement. Dans chacun de ces cas, la relaxation est due à l'association de deux mécanismes impliquant des interactions avec des impuretés paramagnétiques à la surface des C-S-H, ces surfaces comportant des groupements SiOH, CaOH et HOH. La texturation d'une pâte comporte trois étapes. Après une période de latence, l'hydratation s'accélère. La formation des C-S-H implique le développement de la surface associée : ce phénomène est lié à la décroissance progressive de la valeur du T1. Ensuite se dissocient quatre grandes familles de porosité dont trois sont extra-lamellaires. Alors que la réaction d'hydratation est terminée, ces trois familles évoluent vers la formation d'une distribution en loi de puissance. La modification des paramètres de cure influence essentiellement les proportions des deux plus grandes échelles de porosité. La perte de l'organisation en loi d'échelle ou du moins la diminution de son coefficient sont associées à une diminution des modules d'élasticité. C'est le cas lorsque le rapport e/c est supérieur à 0,4 ou quand la température de cure dépasse 50°C. L'ajout de fumée de silice ou l'augmentation de la température de cure, entre 20 et 50°C, accélère la cinétique de texturation. La présence de fumée de silice fait également apparaître une famille de pores supplémentaire aux échelles supérieures.
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Švéda, Matěj. "Vliv různé technologie mletí na vlastnosti Portlandského cementu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-295660.
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This diploma thesis compares impact of various high-energy grinding technologies on crystallographic and granulometric properties of portland cement. It also observes the influence of the conventional and high-speed grinding technology on the resulting physical and mechanical properties of portland cement, depending on the storage time.
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Wu, Yi-Chung, and 吳懿君. "Study of collagen/tricalcium silicate bone glue." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/5z77v2.
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碩士國立臺北科技大學
生物科技研究所
100
In this study, the aim is to develop a novel bone glue composed of tricalcium silicate and high proportion of type I collagen. The bone glue has plasticity in the early stage and will self-set after hydration to provide mechanical strength. Tricalcium silicate (C3S) is one of the main components of Portland cement, with the ability of rapid hydration to harden in a short period of time. It was reported to induce the formation of bone-like apatite and with excellent bone binding capacity in vitro and in vivo. Type I collagen, the main distribution of the majority of connective tissue in the skin, hard bone and blood vessels, plays important roles in tissue remodeling, wound healing and bone reconstruction. Carboxymethyl cellulose (CMC) is a cellulose-based ring hydroxyl methyl substituted derivative. Depending on the degree of substitution, CMC provides different levels of the sticky property and has been widely used in biomedical products in the recent years. In this experiment, sodium carboxymethyl cellulose with medium degree of substitution was applied to increase the adhesion property of the bone glue. Mechanical property test, surface morphology observation, crystalline phase analysis, in vitro pH value measurement, ions releasing, cytotoxicity test with MG 63 cell line and the drug releasing test including antibiotics and nonsteroidal anti-inflammatory were carried out. The results indicated that bone glue containing 40% collagen, Glue 40, had the following advantages, including shorter working time and setting time, about 11 and 150 minutes, respectively; better adhesion ability in vitro; higher adhesive strength about 416 Kpa; higher tensile strength about 167 Kpa. After seven days curing in the simulated body fluid, Glue 40 was cemented to be block and the changes of pH value was controlled between 7~9. Furthermore, Glue 40 was selected for advanced investigations. After seven days of curing in the saturated vapor of water, the compressive strength of Glue 40 increased with time and reached the maximum value of 500 Kpa. In addition, the additive of CMC not only enhanced the viscosity of the material, but also promoted the proliferation of MG 63 cells. Results of tetracycline releasing test showed that Glue 40 had the ability of initial burst, from 4% to 13%, and then maintained about 20%. Results of diclofenac sodium releasing test showed that after two days the release increased from 46% to 53%, and then maintained about 53%. Concluding the results of tests, Glue 40 has great potential to be a novel bone glue carrying with drugs.
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Chuang, Ya-Chien, and 莊雅茜. "Synthesis and structural elucidation of tricalcium silicate biomaterials." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/94491665419929982727.
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碩士國立臺灣大學
化學研究所
100
Tricalcium silicate (Ca3SiO5, C3S), the main component of mineral trioxide aggregate (MTA), is a potential dental material because of its favorable sealing ability, bioactivity, and biocompatibility. Pure phase of C3S, however, could only be obtained at 1400 degreeC or above. The requirement of high temperature and the poor compressive strength of C3S are undesirable for its clinical applications. Fluoride ions, as a fluxing reagent, can significantly lower the calcination temperature for C3S formation. In this study, C3S are prepared in the presence of NaF by co-precipitation method. By adding 0 to 2 wt% of NaF, different polymorphs of C3S are obtained from 1100 to 1400 degreeC. At 1400 degreeC, the triclinic phase of C3S is the major product, with or without the addition of fluoride. At a temperature of 1100 to 1250 degreeC, the rhombohedral phase of C3S could be obtained by doping 1 to 2 wt% of NaF. In the absence of fluoride ions, however, only dicalcium silicate (C2S) would be formed. In addition to lowering the formation temperature, the setting time and microhardness of C3S can also be improved by the addition of fluorides. The 29Si magic-angle spinning NMR spectra of the rhombohedral C3S show a broad Q0 peak spanning the range from -69 to -75 ppm, whereas there are seven distinct sharp peaks (FWHM ~0.5 ppm) in the same chemical shift range of the Q0 site for the triclinic C3S samples. In other words, the triclinic phase of C3S has significantly higher crystallinity than the rhombohedral phase. Based on a series of 29Si–29Si double-quantum/single-quantum spectra, we have narrowed down the spectral assignments of the resolved seven resonances to two possible scenarios.
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Lin, Kuan-Hung, and 林官鴻. "Study of γ-Polyglutamic Acid/Tricalcium Silicate Composite Bone Cement." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/er8au5.
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碩士國立臺北科技大學
生化與生醫工程研究所
102
Bone cement, a biomaterial with self-curing properties, is used to fill bone defects of different sizes for its injectability and plasticity. Tricalcium silicate (C3S), the main component of Portland cement, is also widely used in terms of biomedical materials. It has good biocompatibility and ability of self-curing to serve as bone cement as a result. And after curing it has certain mechanical strength but easily being broken. γ-PGA is a natural, non-toxic, highly biocompatible and edible polymer. In order to improve the physical properties of tricalcium silicate cement, in the study we prepared γ-polyglutamic acid/tricalcium silicate composite bone cement and tested its properties. Tricalcium silicate was synthesized by sol-gel method. The C3S powder was grinded and calcined in electrically heated furnace in an air atmosphere at 1400oC for 4h. The C3S powder was passed through a No. 400 sieve and mixed with different proportions of γ-PGA. With a ratio of powder/liquid 2:1, the powder was mixed with 10-wt % NaH2PO4 solution to make of the composite bone cement. Due to PGA containing carboxyl, the chelation reaction carried out when combined with tricalcium silicate. After a serious of materials characteristics and biocompatibility evaluations, the potential of the composite to be an ideal bone cement was investigated.
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Wang, Wei-chuan, and 王偉全. "Development of new sol-gel tricalcium silicate cements in endodontic applications." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/65627014853310195330.
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碩士國立臺灣大學
臨床牙醫學研究所
99
An ideal repair material plays an important role in the success of endodontic repair therapy including retrograde filling, perforation repair and vital pulp therapy. There are many repair materials have been used in endodontic applications, but none of these could fit the requirements of ideal material. Mineral trioxide aggregate (MTA) has been currently considered as a potential material used in endodontic repair treatments with promising results, which may caused by its major component - the tricalcium silicate (C3S). However, several disadvantages of MTA have been reported such as long setting time, difficulty in handling, and the high arsenic levels contained. Calcium silicate ceramics (CSCs) without toxic ingredients, developed by our research team, are surface bioactive ceramics presenting the similar behaviors in hydration, cell-material interaction and bioactivity to MTA. But the large amount of CaO remained in the high temperature sintering CSCs caused the low chemical reactivity and long setting time. In this study, we developed the porous C3S to enhance their setting reaction by applying sol-gel process, and further investigated their potential using in endodontic applications. This study was conducted to two sections. In the first section, we synthesized tricalcium silicate via sol-gel process (sC3S) following Tsai’s protocol, and evaluated its physical-chemical and clinical properties with commercial MTA and conventional-sintered C3S as compared groups. The results of X-ray diffraction (XRD) analysis showed the similar patterns in sC3S and C3S powders. After hydrated, peaks corresponding to reactants decreased, and peaks corresponding to hydration products of calcium hydroxide and calcium carbonate were recorded by XRD in both groups. Furthermore, the microstructures of C3S and sC3S hydrates were similar, which became more compact structure when time increased. Scanning electron microscope indicated the smaller particle size and porous texture of sC3S powder. In addition, sC3S presented the significant short setting time (12±0.8min) than those of C3S (177±10min), WMTA (172±8min) and GMTA (114±5min) gourps. In the push-out bonding test, there was no significant difference between sC3S (12.96±4.1 MPa), C3S (11.11±3.9MPa), WMTA (16.2±4.5 MPa) and GMTA (15.78±3.8 MPa). To consider the high level content of residual calcium oxide and unacceptable compressive strength (20.21±3.26 MPa) of previous synthesized sC3S, the protocols of sol-gel process were be modified by changing the mixing order (r ratio) and the concentration of catalyst to improve the properties of the material in the second section. The results showed that the changes in r ratio and the concentration of catalyst would not affect the porous texture and crystal phases of the produced sC3S powder, except the decline of the intensities of the peaks corresponded to calcium oxide. After hydration, the crystals over the outer surface changed their shapes form bar-like crystals to plate-like crystals with 3D structure when the catalyst decreased in concentration. In comparison to the previous synthesized sC3S in first section, the modification of sol-gel process by changing the r ratio and the concentration of catalyst would slightly prolong the setting time of products (28min~34min), but still significantly shorter than that of commercial MTA (p<0.001). Meanwhile, the decrease of the concentration of catalyst in sol-gel process would also improve the compressive strength of products (68.14±7.12MPa), which was much better than that of MTA (p<0.001). In conclusion, sol-gel process could produce porous sC3S with a clinical significant short setting time. Furthermore, the modification of r ratio and the concentration of catalyst in sol-gel process could improve the gelation and the purity of products, and enhance their compressive strength after hydration. Based on these findings, sol-gel synthesized tricalcium silicate is a potential ideal material in endodontic applications.
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Su, Yu-Chieh, and 蘇育傑. "Study of Polymethylmethacrylate / Tricalcium Silicate Paste Organic-inorganic Hybrid Bone Cement." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/3dje6y.
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碩士國立臺北科技大學
化學工程與生物科技系生化與生醫工程碩士班
105
Bone cement is used as a kind of orthopedic material for surgical filling and bone void filler because of its characteristics of self-hardening, good injectibility and moldability. Tricalcium silicate (TCS), the main component of Portland cement, is widely used in terms of biomedical materials. It has good biocompatibility and self-curing ability to serve as a bone cement. TCS bone cement can reach certain level of mechanical strength after setting, but this is unfortunately a brittle material. Polymethylmethacrylate (PMMA) cement has been used in orthopedics for more than seven decades because of its high compressive strength, viscosity, moldability and rapid setting ability. Nevertheless, the heat produced during polymerization could usually challenge its direct bonding to the surrounding bone tissue, which would eventually lead to aseptic loosening. In this study, bioceramics-TCS was chosen to bond directly to the surrounding bone tissue while PMMA could provide good rigidity. These two materials as a composite would complement each other and reduce the problems of loosening due to the high exothermic reaction of PMMA and brittleness of TCS. Therefore, PMMA was combined with TCS to form a composite bone cement. TCS was synthesized by sol-gel method. TCS was calcined in air at 1400°C for 4h and grinded into powder. TCS powder was then sieved through a 400 mesh size sieve to collect powders ≤ 38µm. TCS powder was mixed with citric acid solution at a powder/liquid ratio of 2:1, and then mixed with PMMA in paste form in different ratios to analyze the material properties and biocompatibility. The results showed that the addition of 0.5M citric acid could effectively reduce the setting time of TCS bone cement. The setting-time is in accordance with the regulation of ISO-5833 (Implants for surgery -- Acrylic resin cements) in the range of 5-15 min. For TCS/PMMA composite bone cement, higher TCS ratio would lead to lower temperature produced during polymerization. The curing temperature of the cement was successfully reduced with TCS addition with the highest temperature from 50.4°C of PMMA to the lowest of 39.1°C of TCS 30. In initial test of biocompatibility, specimens were soaked in artificial simulated body fluid (SBF). The pH of the SBF soaked with pure TCS was strongly alkaline while the addition of PMMA could successfully reduce the pH to the range of 7.0-8.5. In addition, there was bone like apatite precipitated on the material surface in 7 days as confirmed by XRD and SEM observations. In vitro studies were proceeded using human osteoblast cell line (MG-63) cultured directly on the materials or in the extracts. The results of cell viability measured using MTT and alkaline phosphatase (ALP) activity showed that the TCS/PMMA cement had great biocompatibility and osteoconductivity. In conclusion, this composite bone cement of PMMA combined with TCS has great potential in orthopedics to serve as bone restoration material.
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"Diffraction investigations of cement clinker and tricalcium silicate using Rietveld analysis." Thesis, University of Technology, Sydney. Department of Chemistry, Materials & Forensic Sciences, 2003. http://hdl.handle.net/10453/20345.
Full textAbstract:
University of Technology, Sydney. Department of Chemistry, Materials & Forensic Sciences.Cement is the world's most popular building material, yet surprisingly its composition is not fully understood. Due to the complex nature of cement constituents, there is currently no reliable method to quantitatively determine the composition of cement. Partly this arises from the fact that the crystal structure of the main component of cement, tricalcium silicate, has not been fully determined. There has been an increase in the use of Rietveld refinement of powder diffraction data for the analysis of cement in recent years. The method has emerged as a valuable tool for the quantitative determination of the composition of cement. A further advantage of the method is its ability to refine complex crystal structures, such as tricalcium silicate. Despite the increased application of this method, few publications exist concerning the evaluation or improvement of the method for the purpose of cement analysis. In this work, the Rietveld method has been critically investigated as a tool for the identification and quantification of the different phases in cement clinker. Laboratory X-ray, synchrotron, neutron, and combined diffraction data are all used in the investigations. For the first time, comparisons of analysis results using various sources are made, rather than comparing the results from various methods. Inconsistencies in the results were found, and their causes were investigated and identified. The reliability of this method was shown to be dependent on the quality of the diffraction data, both in terms of the counting statistics and the resolution, and on the ability of the structures used in the Rietveld model to describe the phases in the sample. The only previously existing structural model for triclinic tricalcium silicate is shown, in this work, inadequate as a description of the form found in cement. Consequently, the triclinic crystal structures of tricalcium silicate were re-investigated. Using synchrotron powder diffraction data, the lattice dynamics during the T1-T2 transition were observed in detail for the first time. Superstructure reflections were observed for the two structures. The first model for the average sub-structure of the T2 form is presented. Structural modulation in the T1 form was re-investigated. The parent sub-structure, suitable for Rietveld refinement, corresponding modulation wave-vector, and superspace group of the superstructure, were identified.
35
"Diffraction Investigations of Cement Clinker and Tricalcium Silicate using Rietveld Analysis." University of Technology, Sydney. Department of Chemistry, Materials & Forensic Sciences, 2003. http://hdl.handle.net/2100/328.
Full textAbstract:
Cement is the world's most popular building material, yet surprisingly its composition is not fully understood. Due to the complex nature of cement constituents, there is currently no reliable method to quantitatively determine the composition of cement. Partly this arises from the fact that the crystal structure of the main component of cement, tricalcium silicate, has not been fully determined. There has been an increase in the use of Rietveld refinement of powder diffraction data for the analysis of cement in recent years. The method has emerged as a valuable tool for the quantitative determination of the composition of cement. A further advantage of the method is its ability to refine complex crystal structures, such as tricalcium silicate. Despite the increased application of this method, few publications exist concerning the evaluation or improvement of the method for the purpose of cement analysis. In this work, the Rietveld method has been critically investigated as a tool for the identification and quantification of the different phases in cement clinker. Laboratory X-ray, synchrotron, neutron, and combined diffraction data are all used in the investigations. For the first time, comparisons of analysis results using various sources are made, rather than comparing the results from various methods. Inconsistencies in the results were found, and their causes were investigated and identified. The reliability of this method was shown to be dependent on the quality of the diffraction data, both in terms of the counting statistics and the resolution, and on the ability of the structures used in the Rietveld model to describe the phases in the sample. The only previously existing structural model for triclinic tricalcium silicate is shown, in this work, inadequate as a description of the form found in cement. Consequently, the triclinic crystal structures of tricalcium silicate were re-investigated. Using synchrotron powder diffraction data, the lattice dynamics during the T1-T2 transition were observed in detail for the first time. Superstructure reflections were observed for the two structures. The first model for the average sub-structure of the T2 form is presented. Structural modulation in the T1 form was re-investigated. The parent sub-structure, suitable for Rietveld refinement, corresponding modulation wave-vector, and superspace group of the superstructure, were identified.
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Huang, Ying-Chieh, and 黃瑩潔. "Effect of tricalcium aluminate on material properties, bioactivity and biocompatibility of calcium silicate ceramics." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/10171202611979068102.
Full textAbstract:
碩士國立臺灣大學
臨床牙醫學研究所
99
In dentistry, the goal of vital pulp therapy involves removing diseased pulp tissue and covering the remaining undamaged tissue with appropriate materials to induce pulp regeneration. Although plausible clinical results could often be achieved, the actual mechanism of pulp-dentin repair is still unknown. New materials need to be developed for reliable prognosis. The purpose of this study was to examine the physico-chemical properties and biological performances of novel calcium silicate biomaterials prepared from mixing different ratio of tricalcium silicate(C3S) and tricalcium aluminate(C3A) which aimed to improve the setting time which was compared with that of ProRoot white MTA without any change in biological properties. This study contained three experimental groups which contain C3S and C3A with different ratio (C3S/C3A: 90/10, 70/30, 50/50) and were fabricated with sol-gel technique; white-colored ProRoot MTA (Dentsply) was comparable group. The setting times, micro-hardness value, morphology and phase composition of hydration products and ex vivo bioactivity were evaluated, as well as the biocompatibility and mineralization, which use of MTT assay to evaluate cytotoxicity and use of ALP assay and Alizarin test to evaluate mineralization. As solid phases determined by XRD, the material powder with different C3A content were proved. The initial setting times of 70/30, 50/50 groups were in the range of 10-25 minutes, which are significantly (p<0.05, ANOVA and post-hoc test) lower than those obtained for white-colored ProRoot MTA (165 minutes) and 90/10 group(81 minutes). The micro-hardness of 50/50 and 70/30 were also significantly(p<0.05) higher than ProRoot MTA in the first day. All groups demonstrated ex vivo bioactivity when they came into contact with phosphate ions. The biocompatibility results of all groups were as good as the negative control except 50/50 with mild cytotoxicity. Results of mineralization test showed that all groups could induce hard tissue formation. Then we concluded in this study that, first, 90/10 group has optimal compressive strength, biocompatibility, and mineralization ability. Moreover, its material property is more reactive than white MTA. Second, with C3A increased to 30% to 50% in calcium silicate ceramics significantly improved setting time and early microhardness of the material, however, also exacerbating its material strength and biological properties.
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Huang, Xiao-Juan, and 黃筱娟. "Development of Poly-L-Lactic Acid/Tricalcium Silicate Composite Film for Leakage Prevention in Percutaneous Kyphoplasty." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/r58ee4.
Full textAbstract:
碩士國立臺北科技大學
化學工程與生物科技系化學工程碩士班（碩士在職專班）
105
For people aged 50 years or over, osteoporosis caused by spinal compression fractures is a common cause of pain. In recent years, percutaneous vertebroplasty and percutaneus balloon kyphoplasty become the most accepted treatments for these fractures. The main concern with percutaneous kyphoplasty is high incidence of bone cement leakage and other resulting complications; therefore, this experiment aimed to make a biodegradable film casing to replace the conventional balloon to improve the leakage problem. Polylactic acid is a biomaterial with good bioabsorbability, biodegradability and good environmental affinity, as a polymeric material, it attracts considerable attention in recent years. Poly-L-lactic acid (PLLA), an optical isomer of polylactic acid, is often used in different industrial or medical applications. Tricalcium silicate (C3S) is the main component of Portland cement, with good biocompatibility and rapid hydration ability, widely used in biomaterials. PLLA was first dissolved in chloroform, and calcium silicate was then added to the polymer solution. The composite film with anti-permeation property was prepared by the solution casting method. In this study, we first explored the effects of different concentrations of tricalcium silicate (C3S) on the mechanical properties of the film. It was found that the addition of 1wt% C3S powder worked best in poly-L-lactic acid solution balancing all parameters. With an increase of C3S content, the Young s modulus of the composite film also increased. The maximum stress of PLLA/C3S film was 13.03 MPa and the fractural strain was 157%. TGA and DSC thermal properties of the film showed no residual chloroform on the film, the thermal cracking temperatures of both PLLA and PLLA/C3S films were around 385°C. The addition of C3S to the film was non-homogeneous nucleation. The cold crystallization peak appeared before Tg point could promote the film to the melting point state. The film was immersed in artificial simulated body fluid (SBF), whereas the pH value was maintained at about 7.4, and the apatite deposited on the material after 8 hours of soaking. Release of silicon from PLLA/C3S film was 15 ppm after 21 days of soaking in SBF. By considering the mechanical properties, in vitro test, cell experiments and other experimental results of the material, this PLLA/C3S film has good biocompatible and anti-leakage potential to be applied to percutaneous balloon kyphoplasty.
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Fan, Kuei-Sheng, and 范貴盛. "Study of Tricalcium Silicate Doped with Strontium Prepared through a Sol-gel Process and Its Composite with Hydroxyapatite." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/y6v97d.
Full textAbstract:
碩士國立臺北科技大學
化學工程研究所
99
In this study, we successfully prepared tricalcium silicate (Ca3SiO5, C3S) doped with a series of strontium (SrxCa3-xSiO5, X= 0.0075 to 0.06) through a sol-gel process. The materials properties including setting property, crystallinity, microstructure and mechanical strength were characterized. Incubation in simulated body fluid was carried out to evaluate the ions releasing and curing behaviors in liquid. Cytotoxcity of the setting block was evaluated with L929 cell-line cultivation. To form a self-setting slurry, the powders were mixed with 10 wt% NaH2PO4 solution. The results showed that the working time of prepared slurries were all less than 10 minutes. Slurry of Sr0.015Ca2.985SiO5 had shortest setting, around 43 minutes. Slurry of Sr0.0525Ca2.9475SiO5 had 69 min setting time, however, and the highest compressive strength 42 MPa after 14 days curing. Results of simulated body fluid incubation study showed that apatite would rapidly form onto the materials, which indicated the well surface bioactivity. The final pH value was 11.7 with high Sr2+ release 135.6 ppm. The cell viability of L929 cell-line was 66% with the treatment of extraction solution using setting block 25 mg/mL, and 98% for 10 mg/mL. Furthermore, a Ca-P-Si composite composed of Sr0.0525Ca2.9475SiO5/Hydroxyapatite (weight ratio of 3) was prepared through a two steps sol-gel process. We successfully decreased pH value and setting time to 8.9 and 43.6 min, respectively. The cell viability of L929 cell-line raised to 107% for 25 mg/mL. The prepared (75 wt%)Sr0.0525Ca2.9475SiO5/(25 wt%)HAp has great potential in bone restoration applications.
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Pereira, João António Abreu. "Characterization of dental cements by computed tomography techniques." Master's thesis, 2021. http://hdl.handle.net/10773/30910.
Full textAbstract:
Nowadays, dental cements are part of the fundamental materials in several
dental treatments, in order to solve problems usually related to bacterial
infections that occur in the dentition and that need an adequate restoration that
can maintain the integrity of that same dentition. Dental cement is essential in
root canal treatments (often called dental devitalization), and its main objective
is to prevent the occurrence of a second infection, so it is necessary that the
cements used seal the entire space between the canal system roots and the
surrounding tissues so as not to allow the passage of microorganisms. It is also
important that the cements have antimicrobial properties, however, this capacity
of the materials used in the production of the cements ends up deteriorating with
the passage of time, making the task of inhibiting a secondary infection difficult.
The porosity of cements is directly linked to the formation of these biofilms, the
smaller this is, the less the possibility of bacteria entering the interior, which
makes the percentage of porosity related to the probability of formation of a
bacterial biofilm responsible for injuries such as post-treatment apical
periodontitis. Micro-CT, a non-destructive technology (NDT), was the technique
chosen for the analysis of dental cements using Skyscan 2211 and allowed for
a careful study of porosity throughout the sample volume. This technique made
possible not only the analysis of the porosity inherent in each of the dental
cements analyzed, but also provided information of enormous importance
regarding the dimensions of the pores present in each sample.Hoje em dia, os cimentos dentários fazem parte dos materiais fundamentais em diversos tratamentos dentários, com o intuito de resolver problemas geralmente relacionados com infeções bacterianas que ocorrem na dentição e que precisam de uma restauração adequada que consiga manter a integridade dessa mesma dentição. O cimento dentário é fundamental em tratamentos de canais radiculares (muitas vezes chamada de desvitalização dentária), e tem como objetivo principal impedir a ocorrência de uma segunda infeção. Desta forma, é necessário que os cimentos utilizados vedem todo o espaço entre o sistema de canais radiculares e os tecidos circundantes de maneira a não permitir a passagem de microorganismos. É também importante que os cimentos apresentem propriedades antimicrobianas. No entanto, esta capacidade dos materiais utilizados na produção dos cimentos acaba por se deteriorar com a passagem do tempo, tornando se difícil a tarefa de inibir uma infeção secundária. A porosidade dos cimentos está diretamente ligada à formação dos biofilmes; quanto mais reduzida esta for, menor será a possibilidade da entrada de bactérias no interior destes, o que torna relacionável a percentagem de porosidade com a probabilidade de formação de um biofilme bacteriano responsável por lesões como a periodontite apical pós-tratamento. A micro-CT, uma tecnologia não-destrutiva (NDT), foi a técnica escolhida para a análise dos cimentos dentários através do Skyscan 2211, e permitiu um estudo cuidado da porosidade por todo o volume das amostras. Esta técnica tornou possível não só a análise da porosidade inerente em cada um dos cimentos dentários analisados, mas também disponibilizou informação de enorme relevo relativamente às dimensões dos poros presentes em cada amostra.
Mestrado em Materiais e Dispositivos Biomédicos
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Varela, Montilla María Cristina. "The use of bioinductor materials for vital pulp therapy in immature permanent teeth: narrative review." Master's thesis, 2021. http://hdl.handle.net/10284/10842.
Full textAbstract:
Background: Dental pulp preservation is essential, especially in young permanent teeth. Nowadays, with the development of biomaterials and advances in pulp biology, the preservation of dental pulp based on regenerative therapies with the use of new biomaterials could be achieve.
Objective: Analyse the use of bioinductive materials for vital pulp therapy in immature permanent teeth.
Materials and methods: A narrative review of publications, between the years 2000 and 2021, retrieved from “PubMed and B-ON” database and search engines of indexed scientific journals. 29 articles were selected according with the inclusion criteria of comparing bioinductive materials used in pulp treatment, based on biological principles and the behaviour of such materials in pulp treatment.
Conclusions: Vital pulp therapy in immature permanent teeth has been successful, especially, with the use of bioinductive materials like Mineral Trioxide Aggregate which is the most recommended.Introdução: A preservação da polpa dentária é essencial, principalmente em dentes permanentes jovens. Atualmente, com o desenvolvimento dos biomateriais e avanços na biologia pulpar, pode-se alcançar a preservação da polpa dentária baseada em terapias regenerativas com o uso de novos biomateriais. Objetivo: Analisar o uso de materiais bioindutivos na terapia da polpa vital em dentes permanentes imaturos. Materiais e métodos: Uma revisão narrativa de publicações, entre os anos de 2000 e 2021, recuperadas dos motores de busca “PubMed e B-ON” de revistas científicas indexadas. 29 artigos foram selecionados de acordo com os critérios de inclusão de comparação de materiais bioindutivos utilizados no tratamento da polpa, com base nos princípios biológicos e no comportamento desses materiais no tratamento da polpa. Conclusões: A terapia da polpa vital em dentes permanentes imaturos tem tido sucesso, principalmente, com o uso de materiais bioindutivos como o Agregado de Trióxido Mineral que é o mais recomendado.