Devido à demanda dos países em desenvolvimento, a produção de cimento e as emissões de CO2 relacionadas aumenta progressivamente, colocando esta indústria sob pressão devido às preocupações com o aquecimento global. Como diminuir a produção não é uma opção sustentável do ponto de vista social, deve-se primar pela diminuição dos impactos ambientais mantendo-se o aumento da produção. Porém, as principais estratégias de redução das emissões substituição de clínquer por adições, aumento da eficiência de fornos e uso de combustíveis alternativos não são capazes de uma redução que compense o crescimento da produção, mesmo com a disseminação dos maiores esforços industriais possíveis, devido a limites tecnológicos e de disponibilidade de materiais. A captura e sequestro de carbono, por sua vez, pode vir a aumentar significativamente o custo do cimento, prejudicando justamente os países mais necessitados. Novas alternativas são necessárias. Uma delas, ainda pouco desenvolvida, é o aumento da eficiência do uso dos ligantes em materiais cimentícios, como os concretos. Esta tese tem o objetivo de explorar o potencial desta estratégia para contribuir à mitigação das emissões de CO2 da cadeia concreto/cimento. O êxito nesta tarefa tem relação direta com o uso de ferramentas de empacotamento e dispersão de partículas para permitir comportamento reológico adequado à aplicação com uso de menor teor de água na mistura. O trabalho foi dividido em três etapas: 1) levantamento de dados para criação de benchmark da tecnologia atual de concretos com relação e eficiência no uso dos ligantes através de dois indicadores de eficiência Índice de Ligantes (IL) e Índice de CO2 (IC); 2) levantamento da teoria de empacotamento e dispersão de partículas; e 3) estudo experimental demonstrando como a eficiência do uso dos ligantes pode ser aumentada através da aplicação dos conceitos da etapa 2, do controle mais preciso do comportamento reológico e do uso de finos inertes para substituir clínquer para obtenção de parâmetros reológicos. Concluiu-se que o potencial de aumento da eficiência é superior a 50%. Porém, sua implantação em escala comercial dependeria de aumento do controle tecnológico das dosagens de concreto e de profundas modificações na cadeia produtiva e na definição de agregados, fillers, cimento e ligantes. / Due to the increasing demand of developing countries, cement production and related CO2 emissions increases steadily, putting industry under pressure due to global warming constraints. As decreasing production is not a sustainable option from social point of view, environmental loads need to be decreased even maintaining the increase of production. However, current strategies for reducing emissions clinker replacement by mineral additions, increase of kiln efficiency and the use of alternative fuels are not capable of a reduction which could compensate the increasing in production, even with the dissemination of highest industrial efforts due to technological and materials availability limits. Carbon capture and storage, by the time, could increase significantly cement cost, which could harm exactly the neediest countries. New alternatives are needed. One of them, few developed yet, is increasing the efficiency of binder use on cementitious materials, such as concretes. This thesis has the aim of exploring the potential of this strategy for contributing to the mitigation of CO2 emissions of concrete/cement chain. The success in this task is directly related to the use of tools of packing and dispersion of particles for allowing an adequate rheological behavior for the application but with a lower water content in the mixture. The thesis was divided in three main steps: 1) literature research for creating a benchmark of current concrete technology in terms of binder efficiency by two efficiency indexes Binder Intensity (BI) and CO2 Intensity (CI); 2) research of particles packing and dispersion theory; and 3) experimental planning for demonstrating how the binder use efficiency can be significantly increased by the use of concepts from step 2, a more precise rheological behavior control and the use of inert fillers for replacing clinker to obtain rheological parameters. It could be concluded that the potential of efficiency increase is higher than 50%. However, the implantation in commercial scale would depend on the increase of technological control in concrete designs, and also on deep changes in the productive chain and in the definitions of aggregates, fillers, cement and binders.

I have worked on many projects, but there are several things that they all had in common. First, nearly all projects involved searching for the structural parameters that governed the macroscopic properties of the polymers and composite materials. A second common denominator is that even though my work was performed in an “academic context”, the goals were targeted toward industrial needs. Lastly, the methods and procedures were similar; they were all based on experimental results obtained for various scales of measurement (see Fig. 1). Hence, multi-scale modeling was very useful and beneficial for these projects. The models developed (mainly numerical and sometimes analytical) were initially derived from experimental evidence and then validated and improved with further experimentation. The refined models provided an efficient means of: (i) optimizing the composites according to specific needs, (ii) better understanding the hierarchical relations between the different scales, (iii) controlling the micro or meso structure and thereby the macroscopic properties. This study of the relations between structure and properties was performed on a wide variety of physical properties and materials. However, the electric and dielectric properties of composites constituted the major- ity of it and will be presented in this report. The remaining property investigations provided supplemental but valuable information. This work often requires altering various conventional experimental techniques or using well-known techniques for new purposes. I also developed, when needed, several unconventional but necessary measurement techniques. This report contains two major parts which are separated according to the nature of the fillers: Part I : Conducting fillers. In the first part, the main interest both for application and fundamental point of view, is related to the changes in properties in the vicinity of the sharp percolation transition. After a brief introduction to the percolation theory, this part will be subdivided in three chapters: Chapter 1. presents a numerical method that correlates the mesostructure to the macroscopic electrical properties both in two and three dimensions. Chapter 2. will show that an external variable (the mechanical stress) may largely alter the microstruc- ture of the percolating network within composites as revealed the macroscopic conductivity. The understanding of the mesoscale changes will be based on the chemical structure of the polymer matrix. Chapter 3. is devoted to the description of a unique case in term of percolation behavior, which made possible the control of the phase arrangement within the composite and thereby the control of the macroscopic resistivity. p. 2 Multiscale relationships in polymer–based heterogeneous systems. . . Part II : Insulating fillers. In the second part, the main interest is to obtain good electrical insulators, i.e. that can withstand large electric fields. This part thus starts with a brief introduction to the common failure mechanisms, associated with the dielectric breakdown and is also divided in three chapters: Chapter 4. is devoted to the description of a numerical simulation of the relationships between mesostructure and dielectric breakdown. Chapter 5. reveals the influence of the processing conditions of a composite utilized in the industry on the microstructure and the quantitative consequences on breakdown properties. Chapter 6. presents the aging of these composites under “real word” conditions which will further be compared to accelerated aging performed in controlled conditions, in the laboratory. A comparison of the two aging situations will furnish a quantitative understanding of the relative influence of the chemical and physical contributions to the aging process. This report will then be concluded with a description of the current and future projects.

Devido à demanda dos países em desenvolvimento, a produção de cimento e as emissões de CO2 relacionadas aumenta progressivamente, colocando esta indústria sob pressão devido às preocupações com o aquecimento global. Como diminuir a produção não é uma opção sustentável do ponto de vista social, deve-se primar pela diminuição dos impactos ambientais mantendo-se o aumento da produção. Porém, as principais estratégias de redução das emissões substituição de clínquer por adições, aumento da eficiência de fornos e uso de combustíveis alternativos não são capazes de uma redução que compense o crescimento da produção, mesmo com a disseminação dos maiores esforços industriais possíveis, devido a limites tecnológicos e de disponibilidade de materiais. A captura e sequestro de carbono, por sua vez, pode vir a aumentar significativamente o custo do cimento, prejudicando justamente os países mais necessitados. Novas alternativas são necessárias. Uma delas, ainda pouco desenvolvida, é o aumento da eficiência do uso dos ligantes em materiais cimentícios, como os concretos. Esta tese tem o objetivo de explorar o potencial desta estratégia para contribuir à mitigação das emissões de CO2 da cadeia concreto/cimento. O êxito nesta tarefa tem relação direta com o uso de ferramentas de empacotamento e dispersão de partículas para permitir comportamento reológico adequado à aplicação com uso de menor teor de água na mistura. O trabalho foi dividido em três etapas: 1) levantamento de dados para criação de benchmark da tecnologia atual de concretos com relação e eficiência no uso dos ligantes através de dois indicadores de eficiência Índice de Ligantes (IL) e Índice de CO2 (IC); 2) levantamento da teoria de empacotamento e dispersão de partículas; e 3) estudo experimental demonstrando como a eficiência do uso dos ligantes pode ser aumentada através da aplicação dos conceitos da etapa 2, do controle mais preciso do comportamento reológico e do uso de finos inertes para substituir clínquer para obtenção de parâmetros reológicos. Concluiu-se que o potencial de aumento da eficiência é superior a 50%. Porém, sua implantação em escala comercial dependeria de aumento do controle tecnológico das dosagens de concreto e de profundas modificações na cadeia produtiva e na definição de agregados, fillers, cimento e ligantes. / Due to the increasing demand of developing countries, cement production and related CO2 emissions increases steadily, putting industry under pressure due to global warming constraints. As decreasing production is not a sustainable option from social point of view, environmental loads need to be decreased even maintaining the increase of production. However, current strategies for reducing emissions clinker replacement by mineral additions, increase of kiln efficiency and the use of alternative fuels are not capable of a reduction which could compensate the increasing in production, even with the dissemination of highest industrial efforts due to technological and materials availability limits. Carbon capture and storage, by the time, could increase significantly cement cost, which could harm exactly the neediest countries. New alternatives are needed. One of them, few developed yet, is increasing the efficiency of binder use on cementitious materials, such as concretes. This thesis has the aim of exploring the potential of this strategy for contributing to the mitigation of CO2 emissions of concrete/cement chain. The success in this task is directly related to the use of tools of packing and dispersion of particles for allowing an adequate rheological behavior for the application but with a lower water content in the mixture. The thesis was divided in three main steps: 1) literature research for creating a benchmark of current concrete technology in terms of binder efficiency by two efficiency indexes Binder Intensity (BI) and CO2 Intensity (CI); 2) research of particles packing and dispersion theory; and 3) experimental planning for demonstrating how the binder use efficiency can be significantly increased by the use of concepts from step 2, a more precise rheological behavior control and the use of inert fillers for replacing clinker to obtain rheological parameters. It could be concluded that the potential of efficiency increase is higher than 50%. However, the implantation in commercial scale would depend on the increase of technological control in concrete designs, and also on deep changes in the productive chain and in the definitions of aggregates, fillers, cement and binders.

Betong är vårt vanligaste byggmaterial men cement står globalt sett för 5 % av CO2-emissionerna. Med detta som bakgrund så har CBI Betonginstitutet anordnat en tävling, där målet är att nå den högsta tryckhållfasthet i en resurssnål betong, med enbart 200 kg cement per m3. Syftet med denna rapport är att utvärdera tävlingen, vilket har utförts genom en omfattande litteraturstudie.  En första analys av de olika betongrecepten medförde att olika grupperingar kunde urskiljas. Ur dessa fanns det tre stycken vars resultat var väldigt bra.   Concrete Innovation Centre, som med ett lågt vct, stora mängder granulerad masugnsslagg (81 %) och lite silikastoft (5 %), uppnådde en tryckhållfasthet på 80 MPa vid 28 dygn och 95 MPa vid 56 dygn.   CBI Stockholm, som genom användandet av ulltrafint filler och silikastoft (4,8 %), uppnådde en tryckhållfasthet på 84 MPa vid 28 dygn och 98 MPa vid 56 dygn.   Thomas Concrete Group som genom att ersätta cementet med en medelmåttig mängd granulerad masugnsslagg (54 %), liten mängd flygaska (9 %), kalkfiller och silikastoft (5 %), uppnådde en tryckhållfasthet på 94 MPa vid 28 dygn och 98 MPa vid 56 dygn.  Det finns således tre recept som vidare studier kan vara rättfärdigade på, de tre ovan nämnda. Det bör tilläggas att en imponerande tryckhållfasthet på nästan 100 MPa, kan uppnås i en betong med enbart 200 kg cement per m3. / Concrete is the most frequently used construction material, but cement globally stands for 5 % of the world’s CO2 emissions. With this as a background CBI Betonginstitutet has arranged a competition, where the goal is to reach the highest compressive strength in a resource economic concrete, with only 200 kg cement per m3. The purpose of this report is to evaluate the competition, which has been done via a substantial literature study.  A first analysis of the different concrete recipes resulted in that different groups could be identified. From these there were three recipes whose result was very good.   Concrete Innovation Centre, which with a low w/c, a high amount of ground granulated blast furnace slag (81 %) and little silica fume (5 %), reached a compressive strength of 80 MPa at 28 days and 95 MPa at 56 days.   CBI Stockholm, which by the usage of ultrafine filler and silica fume (4,8 %), reached a compressive strength of 84 MPa at 28 days and 98 MPa at 56 days.   Thomas Concrete Group, which by replacing the cement with a moderate amount of ground granulated blast furnace slag (54 %), a small amount of fly ash (9 %), lime filler and silica fume (5 %), reached a compressive strength of 94 MPa at 28 days and 98 MPa at 56 days.  The conclusion is that there are three recipes that further studies are justified to continue with, the three mentioned above. It should be added that an impressive concrete compressive strength of almost 100 MPa, can be reach with the use of only 200 kg cement per m3.

In dieser Studie wird ein neuer Ansatz zur Herstellung von Hybridfüllstoffen – Compositen aus Cellulose und präzipitiertem Calciumcarbonat – zur Festigkeitssteigerung in Papier sowie für Anwendungen über die Papierherstellung hinaus (wie bspw. Kunststoff sowie Baufaserplatten, Filter oder Filterhilfsmittel und Foamforming-Produkte) vorgestellt. Das Hauptaugenmerk lag dabei auf der Fällung von CaCO3 über Doppelaustauschreaktion mit Calciumhalogeniden (CaCl2) und Alkalimetallcarbonaten (vorwiegend Na2CO3) auf chemisch und mechanisch modifizierte Faserstoffe in einem Doppelschneckenextruder. Die Hypothese, die dieser Doktorarbeit zugrunde lag, war, dass es möglich ist, CaCO3 durch die reaktive Extrusion direkt auf die Fasern – durch deren veränderte Ladungseigenschaften nach Modifizierung – auszufällen und damit eine irreversible Anlagerung des mineralischen Füllstoffs an den cellulosischen Faserstoff zu generieren. Dabei erwies sich die reaktive Extrusion als vielversprechende Methode sowohl für die Erzeugung carboxymethylierter und fibrillierter Faserstoffe (CMFC) als auch für die in-situ Fällung von CaCO3 direkt auf die CMFC zur Herstellung faserarmierter Füllstoffe mit einer optimierten Füllstoffretention. Darüber hinaus wurde untersucht, inwiefern sich durch die Einstellung der Reaktions- und Prozessparameter die CaCO3-Morphologie, Kristallform und -größe steuern und damit die resultierenden Composite-Eigenschaften einstellen lassen. Zudem konnte durch Anwendungsversuche der neuartigen Hybridfüllstoffe das Potenzial eben dieser in variierenden Endanwendungen – besonders jedoch zur Festigkeitssteigerung in Papier sowie zur Verbesserung des Eigenschaftsprofils in Polypropylen – verdeutlicht werden. Die Untersuchungen zeigten, dass die funktionellen Faserstoffeigenschaften einen entscheidenden Einfluss auf die CaCO3-Fällung – sowohl auf die Kristallisations- als auch Umwandlungsprozesse – und damit auf die resultierenden Hybridfüllstoff-Eigenschaften haben. Besonders wird die Keimbildungsrate durch die hydrogelartige Oberfläche der CMFC reduziert und das Kristallwachstum gefördert, sodass vor-wiegend große CaCO3-Kristalle (≥ 3 µm) an bzw. in der hydrogelartigen Faseroberfläche entstehen. Ebenso konnte gezeigt werden, dass sich auch bei intensiver mechanischer Behandlung bis zu 89 wt.-% des ausgefällten CaCO3 nicht von der CMFC lösen und demnach irreversibel angelagert sind. Dies führt bei der Laborblattbildung zu einer Verbesserung der CaCO3-Retention von 62 wt.-% auf 80 wt.-% bei Kurzfaserzellstoff (BEKP) bzw. von 38 wt.-% auf 91 wt.-% bei Langfaserzellstoff (NBSK). Darüber hinaus konnte gezeigt werden, dass die Hybridfüllstoffe zu einer Festigkeitssteigerung (Tensile Index) um das 1,5-fache bei NBSK- (16,4 Nm/g) und um das 2,1-fache bei BEKP-Laborblättern (26,2 Nm/g) beitragen. Diese Doktorarbeit verdeutlicht, dass die reaktive Extrusion ein innovatives und zukunftsfähiges Verfahren zur Composite-Herstellung ist und die neuartigen Hybridfüllstoffe Potenzial für den vielseitigen Einsatz in variierenden Materialien versprechen.:Abstract I Zusammenfassung II Danksagung III Eidesstattliche Erklärung IV Abbildungsverzeichnis VIII Abkürzungsverzeichnis XIV Formelzeichen und Indizes XVIII Formelverzeichnis XXII Normen- und Methodenverzeichnis XXIII Tabellenverzeichnis XXVI 1 Einleitung 1 2 Allgemeiner Aufbau von Zellstofffasern 3 2.1 Holzquelle Wald 3 2.2 Anatomie des Holzes 3 2.3 Morphologische Eigenschaften und chemische Zusammensetzung der Zellwand 5 2.4 Chemischer Aufbau des Holzes 6 3 Von der Zellstofffaser zur Nanocellulose 11 3.1 Nanocellulosetypen 11 3.2 Mikrofibrillierte Cellulose – MFC 14 3.3 Einsatzmöglichkeiten für MFC 14 3.3.1 Allgemeine Einsatzmöglichkeiten von MFC 14 3.3.2 Einsatz von MFC in der Papierherstellung 15 3.4 Herstellung von MFC 16 3.4.1 Allgemeine Herstellung von MFC 16 3.4.2 Herstellung von MFC im Extruder 18 3.5 Chemische Modifizierung/Vorbehandlung von Faserstoffen 20 3.5.1 Carboxymethylcellulose – CMC 20 3.5.2 TEMPO-Oxidierte Cellulose 22 3.5.3 Carboxymethylierte, fibrillierte Cellulose – CMFC 24 4 Theorie der Fällung und Kristallisation 25 4.1 Fällung und Kristallisation im Allgemeinen 25 4.2 Keim- und Partikelbildung 29 4.2.1 Änderung der freien Enthalpie bei der Keim- und Partikelbildung 29 4.2.2 Löslichkeit und Übersättigung 30 4.2.3 Keimbildungskinetik 34 4.2.4 Keimbildungs- und Wachstumsrate 37 4.3 Kristallwachstum 39 4.3.1 Diffusionskontrolliertes und einbaulimitiertes Wachstum 39 4.3.2 Modellansätze von LaMer und Ostwald 41 4.4 Mechanismen zur Beeinflussung von Fällungsreaktionen 43 5 Calciumcarbonat – Eigenschaften, Herstellung, Einsatz 45 5.1 Stoffsystem Calciumcarbonat 45 5.1.1 Eigenschaften und Vorkommen 45 5.1.2 Modifikationen und Kristallformen 47 5.1.3 Bildung der wasserfreien Phasen – Calcit, Aragonit und Vaterit 50 5.1.4 Möglichkeiten zur Steuerung der Modifikationen und Kristallformen 55 5.2 Herstellung von Calciumcarbonat 57 5.2.1 Allgemein 57 5.2.2 Natürliches Calciumcarbonat – GCC 58 5.2.3 Synthetisches Calciumcarbonat – PCC 59 5.2.3.1 Fällung aus Kalkmilch 59 5.2.3.2 Doppelaustauschreaktion 60 5.2.3.3 Weitere technische Fällungs-Methoden 61 5.3 Einsatzmöglichkeiten von Calciumcarbonat 62 5.3.1 Allgemeine Einsatzmöglichkeiten von Calciumcarbonat 62 5.3.2 PCC als funktioneller Füllstoff in der Papierherstellung 63 6 Calciumcarbonat-Fällung an Faseroberflächen 66 6.1 Motivation 66 6.2 Stand der Technik 67 6.2.1 Calciumcarbonat-Fällung an Faseroberflächen zur Hybridfüllstoff-Herstellung 67 6.2.2 Weitere Methoden zur Hybridfüllstoff-Herstellung bzw. zur Verbesserung der Faser-Füllstoff-Interaktion 72 6.3 Prozesse bei der Calciumcarbonat-Fällung an Faseroberflächen und in Hydrogelen 76 7 Problemstellung 81 7.1 Idee und Ziel der Arbeit 81 7.2 Hypothesen der Arbeit 84 8 Material und Methoden 85 8.1 Material 85 8.1.1 Verwendete Zellstoffe und deren Modifizierung 85 8.1.2 Fällungsreagenzien/-chemikalien 86 8.1.3 Weitere Chemikalien und Materialien 87 8.2 Laborfällung 87 8.2.1 Versuchsaufbau 87 8.2.2 Versuchsdurchführung 88 8.3 Extruderfällung 93 8.3.1 Versuchsaufbau 93 8.3.2 Versuchsdurchführung 95 8.4 Messmethoden zur Materialcharakterisierung 98 8.4.1 Überblick über alle angewandten Messmethoden zur Calciumcarbonat-, Faserstoff- sowie Composite-Charakterisierung 98 8.4.2 Themenspezifische und adaptierte Messmethoden sowie Probenpräparation 100 8.5 Anwendung der Composite in unterschiedlichen Produkten 107 8.5.1 Composite-Einsatz in der Laborblattbildung 107 8.5.2 Composite-Einsatz in weiteren Materialien 108 9 Ergebnisse und Diskussion der Fällungsexperimente 111 9.1 Untersuchungen zur Steuerung der Doppelaustauschreaktion zur reinen Calciumcarbonat-Fällung im Labor 111 9.2 Untersuchungen zur Composite-Bildung über Doppelaustauschreaktion im Labor 120 9.3 Untersuchungen zur Composite-Bildung über Doppelaustauschreaktion und Kalkmilchfällung im Extruder 132 9.4 Zusammenfassung der Ergebnisse 149 10 Anwendungsversuche 152 10.1 Definition möglicher Einsatzgebiete für mineralisierte Cellulosestrukturen 152 10.2 Einfluss der Composite in der Laborblattbildung 154 10.3 Einfluss der Composite in anderen Materialien 159 10.4 Zusammenfassung der Ergebnisse 164 11 Zusammenfassung und Ausblick 166 Literaturverzeichnis 169 Anlagenverzeichnis 194 / This study presents a new approach for the production of hybrid fillers – composites of cellulose and precipitated calcium carbonate – for strength enhancement in paper as well as for applications beyond paper production (such as plastics as well as building fibre boards, filters or filter aids and foamforming products). The main focus was on the precipitation of CaCO3 via double exchange reaction with calcium halides (CaCl2) and alkali metal carbonates (mainly Na2CO3) onto chemically and mechanically modified fibrous materials in a twin screw extruder. The hypothesis underlying this PhD thesis was that it is possible to precipitate CaCO3 directly onto the fibres – through their altered charge properties after modification – by reactive extrusion, thus generating an irreversible attachment of the mineral filler to the cellulosic pulp. Reactive extrusion proved to be a promising method both, for the generation of carboxymethylated and fibrillated cellulose (CMFC) and for the in-situ precipitation of CaCO3 directly onto the CMFC for the production of fibre-reinforced fillers with optimised filler retention. Furthermore, it was investigated to what extent the CaCO3 morphology, crystal shape and size can be controlled by adjusting the reaction and process parameters and thus the resulting composite properties. In addition, the potential of the novel hybrid fillers in varying end-use applications – especially for increasing the strength of paper and improving the property profile of polypropylene – was demonstrated in application trials. The investigations showed that the functional fibre properties have a decisive influence on CaCO3 precipitation – both on the crystallisation and conversion processes – and thus on the resulting hybrid filler properties. In particular, the nucleation rate is reduced by the hydrogel-like surface of the CMFC and crystal growth is promoted, so that predominantly large CaCO3 crystals (≥ 3 µm) are formed on or in the hydrogel-like fibre surface. It was also shown that even with intensive mechanical treatment, up to 89 wt. % of the precipitated CaCO3 does not detach from the CMFC and is therefore irreversibly attached. This leads to an improvement in CaCO3 retention in laboratory sheet formation from 62 wt. % to 80 wt. % for hardwood pulp (BEKP) and from 38 wt. % to 91 wt. % for softwood pulp (NBSK). Furthermore, it could be shown that the hybrid fillers contribute to an increase in strength (tensile index) of 1.5 times for NBSK (16.4 Nm/g) and 2.1 times for BEKP laboratory sheets (26.2 Nm/g). This thesis work illustrates that reactive extrusion is an innovative and sustainable process for composite production and that the novel hybrid fillers promise potential for versatile use in varying materials.:Abstract I Zusammenfassung II Danksagung III Eidesstattliche Erklärung IV Abbildungsverzeichnis VIII Abkürzungsverzeichnis XIV Formelzeichen und Indizes XVIII Formelverzeichnis XXII Normen- und Methodenverzeichnis XXIII Tabellenverzeichnis XXVI 1 Einleitung 1 2 Allgemeiner Aufbau von Zellstofffasern 3 2.1 Holzquelle Wald 3 2.2 Anatomie des Holzes 3 2.3 Morphologische Eigenschaften und chemische Zusammensetzung der Zellwand 5 2.4 Chemischer Aufbau des Holzes 6 3 Von der Zellstofffaser zur Nanocellulose 11 3.1 Nanocellulosetypen 11 3.2 Mikrofibrillierte Cellulose – MFC 14 3.3 Einsatzmöglichkeiten für MFC 14 3.3.1 Allgemeine Einsatzmöglichkeiten von MFC 14 3.3.2 Einsatz von MFC in der Papierherstellung 15 3.4 Herstellung von MFC 16 3.4.1 Allgemeine Herstellung von MFC 16 3.4.2 Herstellung von MFC im Extruder 18 3.5 Chemische Modifizierung/Vorbehandlung von Faserstoffen 20 3.5.1 Carboxymethylcellulose – CMC 20 3.5.2 TEMPO-Oxidierte Cellulose 22 3.5.3 Carboxymethylierte, fibrillierte Cellulose – CMFC 24 4 Theorie der Fällung und Kristallisation 25 4.1 Fällung und Kristallisation im Allgemeinen 25 4.2 Keim- und Partikelbildung 29 4.2.1 Änderung der freien Enthalpie bei der Keim- und Partikelbildung 29 4.2.2 Löslichkeit und Übersättigung 30 4.2.3 Keimbildungskinetik 34 4.2.4 Keimbildungs- und Wachstumsrate 37 4.3 Kristallwachstum 39 4.3.1 Diffusionskontrolliertes und einbaulimitiertes Wachstum 39 4.3.2 Modellansätze von LaMer und Ostwald 41 4.4 Mechanismen zur Beeinflussung von Fällungsreaktionen 43 5 Calciumcarbonat – Eigenschaften, Herstellung, Einsatz 45 5.1 Stoffsystem Calciumcarbonat 45 5.1.1 Eigenschaften und Vorkommen 45 5.1.2 Modifikationen und Kristallformen 47 5.1.3 Bildung der wasserfreien Phasen – Calcit, Aragonit und Vaterit 50 5.1.4 Möglichkeiten zur Steuerung der Modifikationen und Kristallformen 55 5.2 Herstellung von Calciumcarbonat 57 5.2.1 Allgemein 57 5.2.2 Natürliches Calciumcarbonat – GCC 58 5.2.3 Synthetisches Calciumcarbonat – PCC 59 5.2.3.1 Fällung aus Kalkmilch 59 5.2.3.2 Doppelaustauschreaktion 60 5.2.3.3 Weitere technische Fällungs-Methoden 61 5.3 Einsatzmöglichkeiten von Calciumcarbonat 62 5.3.1 Allgemeine Einsatzmöglichkeiten von Calciumcarbonat 62 5.3.2 PCC als funktioneller Füllstoff in der Papierherstellung 63 6 Calciumcarbonat-Fällung an Faseroberflächen 66 6.1 Motivation 66 6.2 Stand der Technik 67 6.2.1 Calciumcarbonat-Fällung an Faseroberflächen zur Hybridfüllstoff-Herstellung 67 6.2.2 Weitere Methoden zur Hybridfüllstoff-Herstellung bzw. zur Verbesserung der Faser-Füllstoff-Interaktion 72 6.3 Prozesse bei der Calciumcarbonat-Fällung an Faseroberflächen und in Hydrogelen 76 7 Problemstellung 81 7.1 Idee und Ziel der Arbeit 81 7.2 Hypothesen der Arbeit 84 8 Material und Methoden 85 8.1 Material 85 8.1.1 Verwendete Zellstoffe und deren Modifizierung 85 8.1.2 Fällungsreagenzien/-chemikalien 86 8.1.3 Weitere Chemikalien und Materialien 87 8.2 Laborfällung 87 8.2.1 Versuchsaufbau 87 8.2.2 Versuchsdurchführung 88 8.3 Extruderfällung 93 8.3.1 Versuchsaufbau 93 8.3.2 Versuchsdurchführung 95 8.4 Messmethoden zur Materialcharakterisierung 98 8.4.1 Überblick über alle angewandten Messmethoden zur Calciumcarbonat-, Faserstoff- sowie Composite-Charakterisierung 98 8.4.2 Themenspezifische und adaptierte Messmethoden sowie Probenpräparation 100 8.5 Anwendung der Composite in unterschiedlichen Produkten 107 8.5.1 Composite-Einsatz in der Laborblattbildung 107 8.5.2 Composite-Einsatz in weiteren Materialien 108 9 Ergebnisse und Diskussion der Fällungsexperimente 111 9.1 Untersuchungen zur Steuerung der Doppelaustauschreaktion zur reinen Calciumcarbonat-Fällung im Labor 111 9.2 Untersuchungen zur Composite-Bildung über Doppelaustauschreaktion im Labor 120 9.3 Untersuchungen zur Composite-Bildung über Doppelaustauschreaktion und Kalkmilchfällung im Extruder 132 9.4 Zusammenfassung der Ergebnisse 149 10 Anwendungsversuche 152 10.1 Definition möglicher Einsatzgebiete für mineralisierte Cellulosestrukturen 152 10.2 Einfluss der Composite in der Laborblattbildung 154 10.3 Einfluss der Composite in anderen Materialien 159 10.4 Zusammenfassung der Ergebnisse 164 11 Zusammenfassung und Ausblick 166 Literaturverzeichnis 169 Anlagenverzeichnis 194

Este estudo avaliou propriedades de fratura e seus parâmetros de superfície em composições de pasta de cimento de mesma porosidade capilar, variando o teor de filler calcário como substituinte ao cimento comercial. Ainda, para avaliação do efeito em composições de argamassa, foi avaliada a capacidade de redução de água que essa adição pode proporcionar e seu efeito na resistência mecânica. A avaliação dos parâmetros de fratura ocorreu por ensaio de flexão por carregamento em três pontos, com controle por taxa de deslocamento e as análises de superfície por ensaio de interferometria, em seções de fratura e entalhe. O aumento do teor de filler calcário proporcionou redução da demanda de água nas argamassas, para mesmo comportamento. A redução da demanda foi ainda maior para as composições dispersas com aditivo, em relação à referência com aditivo. As resistências à compressão das argamassas apresentaram boa correlação em relação ao ajuste com todas as composições, enquanto foi observado que argamassas de médio teor de filler podem apresentar mesma resistência à flexão que as argamassas de referência, mesmo que estas apresentem menor porosidade capilar. As pastas ensaiadas à flexão por carregamento três pontos não apresentaram comportamento quase-frágil, impedindo o cálculo da energia de fraturamento. Isto ocorreu devido ao método de ensaio adotado, com configuração inadequada, e que pode ser ajustada através da redução da taxa de deslocamento do ensaio, da geometria dos corpos de prova ou da geometria dos entalhes produzidos. Todas as composições apresentaram insensibilidade à profundidade de entalhe sob as condições de ensaio adotadas, possivelmente devido às falhas de configuração do método. As médias de resistência à flexão e do fator de intensidade de tensão crítico foram maiores para a composição de alto teor de filler, seguidos da referência e da composição de médio teor de filler, respectivamente. Em todas as análises e tipos de superfície estudadas, as composições de alto teor de filler apresentaram maior índice de rugosidade e amplitude entre picos e vales, enquanto não foi identificada diferença entre a referência e a composição de médio teor de filler. Estes dois parâmetros e a raiz quadrática da rugosidade indicaram que a rugosidade das superfícies fraturadas é maior que em superfícies cortadas com disco diamantado. / This study assesses fracture properties and their surface parameters in cement paste compositions of the same capillary porosity, varying the filler content of limestone as a substitute for commercial cement. Also, to evaluate the effect in mortar compositions, the water reduction capacity that this addition can provide and its effect on the mechanical resistance was evaluated. The evaluation of the fracture parameters was performed by three-point loading flexion test with displacement rate control and surface analysis by interferometry test in fracture and notch sections. The increase of limestone filler provided a reduction of the water demand in the mortars, in relation to the reference, for spreading of 265mm in table of consistency. The water demand reduction was even greater for compositions dispersed with admixture, relative to the reference with admixture. The compressive strength of the mortars presented a good correlation in the fit with all the compositions, while it was observed that mortars of medium filler content may have the same flexural strength as the reference mortars, even if they have lower capillary porosity. The pastes tested by three-point loading did not exhibit quasi-fragile behavior, preventing the calculation of fracturing energy. This was due to the inadequately configured test method adopted, which can be adjusted by reducing the test displacement rate, the geometry of the specimens or the geometry of the notches produced. All compositions presented insensitivity to the notch depth under the test conditions adopted, possibly due to method configuration failures. The averages of flexural strength and critical stress intensity factor were higher for the high filler composition, followed by the reference and medium filler composition, respectively. In all analyzes and surface types studied, high filler compositions presented higher roughness and amplitude index between peaks and valleys, while no difference between the reference and medium filler composition was identified. These two parameters and the quadratic root roughness indicated that the roughness of the fractured surfaces is greater than on surfaces cut with diamond disc.

O uso do cimento nas dosagens de materiais cimentícios sempre foi uma preocupação na construção civil por questões de custo. Com o surgimento das discussões sobre sustentabilidade, as preocupações passam a ocorrer também com relação aos impactos ambientais gerados em sua produção, principalmente as emissões de 2. Apesar de grandes esforços industriais para a redução destas emissões, as estratégias adotadas não têm sido eficientes para atingir patamares de redução suficientes. Neste cenário, a substituição de parte do cimento por finos inertes, conhecidos como fíleres, provenientes de matérias-primas abundantes e baratas, podem proporcionar ganhos econômicos e ambientais, já que estes materiais apresentam menor impacto de produção por não necessitarem serem submetidos a processos térmicos. Além disso, a adição de fíleres na matriz cimentícia pode contribuir para o aumento da eficiência dos ligantes, pois possibilita o melhor empacotamento de partículas, com diminuição de vazios, que contribui para a redução do teor de água na mistura o que significa possibilidade de desempenho mecânico satisfatório com menos clínquer. O presente trabalho teve como objetivo avaliar o potencial de substituição de parte do cimento por fíleres de quartzo em pastas cimentícias, visando reduzir o consumo de clínquer. Foram avaliados os comportamentos reológicos e mecânicos de dosagens de pastas e argamassas de clínquer-fíler, verificando o desempenho dos materiais produzidos. Para estudo das pastas foram feitas caracterizações das matérias-primas, ensaios de reologia para determinar o teor ótimo de dispersante, e ensaios de resistência à compressão para teores de água fixos, variando os fíleres com três composições granulométricas distintas. Para avaliação das argamassas, foram realizados ensaios de resistência à compressão e determinados os módulos de elasticidade. A análise dos resultados foi feita por meio de comparativos entre os comportamentos reológicos e mecânicos das misturas, além do cálculo do indicador de eficiência Binder Intensity (BI), que é uma relação entre o consumo de cimento e a resistência mecânica. Os materiais produzidos com fíleres atingiram comportamentos reológicos próximos ao material convencional, mas com teores de água reduzidos, contribuindo para o alcance de boas resistências mecânicas com menor consumo de cimento, e módulos de elasticidade equivalentes. Os resultados obtidos nos II experimentos realizados comprovam os ganhos de eficiência alcançados com a adição de fíleres de quartzo em materiais cimentícios e a viabilidade para aplicação na construção civil. / The use of cement in cementitious materials dosages has always been a concern in civil construction for costs issues. With the emergence of sustainability discussions, also arise concerns about environmental impacts generated in its production, mainly 2 emissions. Although the large industrials efforts to reduce these emissions, the strategies adopted havent been efficient to achieve sufficient reduction levels. In this scenario, partial replacement of cement by inert fines, denominated fillers, from abundant and cheap raw materials, can provide environmental and economic gains, since these materials produce lower environmental impact as they dont need to be submitted to thermal processes. Beyond that, the fillers addition in cementitious matrix can contribute to the increase of binders efficiency, as it allows the particles packaging, with the decreasing of voids, which contributes to the reduction of water content in the mixture which means possibility of satisfactory mechanical performance with less clinker content. Thus, this study aims to evaluate the potential of cement replacement by quartz fíller in cement mixtures, in order to reduce clinkers consumption. Were evaluated the rheological and mechanical behavior of pastes and mortars dosages made of clinker-filler, and was verified the performance of the materials produced. To the paste study, were made raw materials characterizations, rheology tests to determine the optimum dispersant content, and compressive strength tests for fixed water contents, varying three fillers with different particle sizes. For mortars evaluation, were performed compressive strength tests and was determined the elastic modulus. The analysis of the results were made though comparisons between mixtures rheological and mechanical behaviors, besides the calculation of the efficiency index Binder Intensity (BI), which is a relation between cement consumption and the mechanical strength. The materials produced with fillers reached a rhealogical behavior close to the conventional materials behavior, but with reduced water contents, contributing to the achievement of good mechanical resistance with lower cement consumption, and equivalentmodulus of elasticity. The results obtained in the experiments performed demonstrate the efficiency gains achieved with the addition of quartz fillers in cementitious materials and the feasibility for application in the civil construction industry.

Esta pesquisa tem por objetivo contribuir para o melhor entendimento dos efeitos do fíler mineral sobre o comportamento mecânico de misturas asfálticas densas, particularmente em relação ao tipo e teor de fíler. O comportamento mecânico de misturas asfálticas densas foi avaliado em função do tipo e teor de fíler (diferentes propriedades físicas, geométricas, mineralógica e comportamento físico-químico), do tipo de agregado (diferentes origens mineralógicas) e do tipo de ligante asfáltico (diferentes consistências). Para alcançar o objetivo geral, a pesquisa foi dividida em três partes: o estudo da mistura asfáltica completa, através de ensaios mecânicos; o estudo do mástique, resultante da mistura de fíler com ligante asfáltico, através dos ensaios comumente aplicados aos ligantes asfálticos puros; e o estudo do comportamento de trincamento dos mástiques nas temperaturas intermediárias, através das características de energia fratura. A análise de variância dos resultados auxiliou na identificação dos fatores com influência significativa nas propriedades apresentadas pelas misturas e mástiques asfálticos. Quanto aos resultados de vida de fadiga, as misturas asfálticas compostas com cal hidratada apresentaram as maiores vidas de fadiga e quanto maior o teor de fíler, maior a vida de fadiga. Em relação à deformação permanente, as misturas asfálticas contendo o menor teor de fíler apresentam os menores valores de deformação não recuperável, enquanto que as misturas contendo o valor intermediário de fíler apresentam os maiores valores. As propriedades reológicas dos mástiques mostraram que a adição de fíler torna o ligante asfáltico mais rígido e a cal hidratada é o fíler que provoca o maior aumento do valor do G*. A elasticidade do mástique aumenta com a adição dos fileres e é mais expressivo para os mástiques compostos pelo fíler de cal hidratada e cimento Portland. Quanto maior o teor de fíler utilizado, maior a temperatura correspondente a G*/sen \'delta\' \'> ou =\' 1,0 kPa da especificação Superpave, o que pode se refletir em misturas asfálticas com maior resistência à deformação permanente. Nas propriedades a baixa temperatura, a utilização de maiores teores de fíler prejudicam a resposta ao trincamento a baixas temperaturas e diminuem a eficiência na dissipação das tensões formadas durante a contração do ligante asfáltico, quando a temperatura do pavimento cai abruptamente, aumentando a formação de trincas e fissuras. Analisando os resultados da energia de fratura, a adição de fíler no mástique diminui a resistência ao trincamento por fadiga nas temperaturas intermediárias, porém a presença de fíler na mistura durante o envelhecimento torna seus efeitos menos prejudiciais. / The objective of this research is to contribute to the better understanding of mineral filler effects on the mechanical behavior of hot mix asphalt (HMA), particularly related to the filler type and content. The hot mix asphalt mechanical behavior was evaluated according to: the filler type and content (different physical, geometrical, mineralogical properties, and the physical-chemical behavior); the aggregate type (different mineralogical source); and the asphalt binder type (different consistency). To reach the global objective, the research was divided in three parts: the study of the complete HMA, through the mechanical tests; the study of the mastic, resulting from mixture of mineral filler and asphalt binder, through tests commonly applied to pure asphalt binder; and the study of cracking performance behavior at intermediate temperature, through the fracture energy characteristics. The analysis of variance of the results assisted to identify the factors with significant influence in properties of the hot mix and mastic asphalt. Regarding the results of the fatigue life, the HMA composed with the hydrated lime presented the longer fatigue life and the higher the filler content the longer the fatigue life. Related to the permanent deformation, the HMA containing the lowest content of filler presented the lowest non-recoverable strain, while the HMA containing an intermediate value of filler presented the highest values. The mastics rheological properties showed that addition of filler makes the asphalt binder stiffer, and the hydrated lime causes the greatest increase of G*. The mastic elasticity increases with the filler, and its more notorious when the mastic is composed by the hydrated lime and Portland cement. The higher the filler content, the higher the temperature corresponding to G*/sen \'delta\' \'> ou =\' 1,0 kPa of the Superpave specification, which may be reflected in HMA with higher permanent deformation resistance. At low temperature properties, the use of higher filler content prejudice the low temperatures cracking response, and decrease the efficiency of stress dissipation formed during contraction of the asphalt binder when the pavement temperature drops abruptly, increasing the formation of cracks and fissures. Analyzing the energy fracture results, adding filler to the mastic decrease the cracking resistance by fatigue at intermediate temperature, but the filler presence in the mixture during aging makes the effect less damaging.

Submitted by Jadson Francisco de Jesus SILVA (jadson@uefs.br) on 2018-01-30T22:07:52Z No. of bitstreams: 1 Uiliana M?rcia da Silva Merc?s Farias_2017.pdf: 5844655 bytes, checksum: 1df6b86cb5dfd9f89a7bbd299fa1bf93 (MD5) / Made available in DSpace on 2018-01-30T22:07:52Z (GMT). No. of bitstreams: 1 Uiliana M?rcia da Silva Merc?s Farias_2017.pdf: 5844655 bytes, checksum: 1df6b86cb5dfd9f89a7bbd299fa1bf93 (MD5) Previous issue date: 2017-03-20 / The use of waste from Dimension Stone Industry as an inert material can be a good way to promote the sustainability of the construction sector. The Cariri stone is one of the dimension stones explored in state of Ceara, in Brazil. Thus, this work was developed with the main goal of studying a self-compacting concrete production (SCC) using Cariri stone sawdust waste (CSSW) in partial replacement with the natural fine aggregate. The SCC was designed using the method proposed by Melo (2005) considering two w/c ratios (0.57-0.70), and 10% of CSSW. The study was carried out in three stages: material characterization, mortar phase evaluation and SCC phase evaluation. In the fresh state, SCC was evaluated for fluidity, plastic viscosity, blocking capacity and segregation resistance, using V funnel, J-Ring, L-box and segregation column. In the hardened state, the SCC was evaluated for axial compressive strength, splitting tensile strength and water absorption, void index and specific density. The results showed that CSSW improve SCC cohesiveness and homogeneity, and it is feasible to apply up to 10% of CSSW in SCC production. / No sentido de promover a sustentabilidade do setor da constru??o civil, procura-se alternativas para diminuir o impacto ambiental gerado, atrav?s da descoberta de novos materiais alternativos, como os res?duos da ind?stria de beneficiamento de rochas ornamentais. Dentre os tipos de rochas ornamentais exploradas no Brasil, destaca-se um calc?rio laminado conhecido como ?Pedra Cariri?, que ? explorado no estado do Cear?. Assim, esse trabalho foi desenvolvido com o objetivo de estudar a produ??o de concreto autoadens?vel (CAA) utilizando res?duos de serragem de pedra Cariri (RSPC) em substitui??o parcial ao agregado mi?do natural. Utilizando a metodologia de Melo (2005) para produ??o de CAA, foram definidas as rela??es a/c (0,57-0,70). O estudo se deu em tr?s etapas: caracteriza??o dos materiais, fase argamassa e fase CAA. No estado fresco, o CAA foi avaliado quanto ? fluidez, viscosidade pl?stica, habilidade passante e resist?ncia ? segrega??o, por meio do ensaio de espalhamento, funil V, Anel J, Caixa L e coluna de segrega??o. No estado endurecido, o CAA foi avaliado quanto ? resist?ncia ? compress?o axial, ? resist?ncia ? tra??o por compress?o diametral e ? absor??o de ?gua, ?ndice de vazios e massa espec?fica. Os resultados indicaram a possibilidade da aplica??o de at? 10% de RSPC na produ??o de CAA.

Les nanocomposites présentent des propriétés uniques dont l'origine est sujette à débat. Dans ce travail, nous cherchons à déterminer quel est l'impact de la morphologie de la charge et de son état de distribution sur les propriétés des matériaux. Pour cela, nous avons étendu un modèle théorique que nous résolvons numériquement.Nous avons étudié l'effet de la distribution des charges dans la matrice. Nous montrons qu'un état de distribution fortement hétérogène conduit à un renforcement plus important qui s'étend dans une plus large gamme de températures, mais augmente aussi la dissipation d'énergie. Ensuite, nous étudions l'effet de la structure des charges. Des particules parfaitement sphériques sont comparées à des agrégats fractals plus ou moins finement définis. Nous montrons que des objets finement définis peuvent s'imbriquer au sein de la matrice et conduisent à une augmentation du renfort et de la dissipation dans ces matériaux.Puis, nous étudions la réponse de nos systèmes lorsqu'ils sont soumis à une première élongation de forte amplitude. Nous montrons alors qu'un système hétérogène se plastifie localement progressivement au cours de la déformation alors qu'un système homogène présente une plastification catastrophique généralisée à partir d'une déformation critique. Enfin dans une dernière partie nous évaluons la possibilité d'étendre le modèle afin de simuler l'endommagement des nanocomposites. Nous introduisons pour cela un critère rupture local afin de prendre en compte l'endommagement du polymère entre les charges. Nous étudions ensuite comment se comportent les matériaux simulés en faisant varier la morphologie de la charge, son état de distribution et son taux.Ce travail constitue la première étude systématique de l'effet de la morphologie et de la distribution des charges sur les propriétés mécaniques des nanocomposites. Nous montrons que ces paramètres peu contrôlés sont pourtant des paramètres clés et peuvent servir à optimiser les propriétés d’usage d'un nanocomposite / Nano-filled elastomer composites are used in a very broad range of applications such as tires, damping materials and impact modifiers. The addition of nanoscale rigid particles in a polymer matrix induces nonlinear effects that are not yet fully understood far above the glass transition temperature of the pure matrix. A model of the reinforcement of nanocomposites based on the reduced mobility of the polymer confined between two spherical filler particles has been developed over the last ten years. In order to study the influence of the filler shape, structure, size, and dispersion state, we have extended the model were the morphology of the fillers is defined explicitly as spherical particles aggregated in the polymer matrix. The model is then solved by mesoscale numerical simulation in order to describe the mechanical properties of the nanocomposite. We study the mechanical response of nanocomposite filled with aggregates of different shapes and distribution state to deformations of various amplitudes in the reinforcement regime. We show that the mechanical behavior of nanocomposites strongly depends on the filler morphology and we propose that stress-relaxation mechanisms in the material are related to the disorder (particle size, aggregation number, distribution state) in the filler population. In a second part of this work, we study the mechanical response at larger amplitude in both a non-destructive and destructive regime. For that matter, the model has been extended in order to account for damaging of the polymer between filler particles.Our model opens the path for the development of systems with tailored properties by adjusting the fillers morphology and distribution.