Portland cement-based products are the most commonly used building materials. However, it is well known that the production of OPC not only consumes a significant amount of natural resources and energy but also releases high quantity of carbon dioxide (CO2) to the atmosphere. Purpose of this work is to develop new cementitious material similar to Portland cement-based concrete, which is convenient in terms of energy and is environmental-friendly at once. This work presents preparation, composition and properties of inorganic aluminosilicate polymer, called geopolymer, synthesized from blast furnace slag and fly ash, activated by sodium hydroxide and cement kiln dust. Study of the microstructure was based on SEM-EDX-WDX, TG-DTA-EGA and XRD analysis.

The presented diploma thesis deals with the potential use of colloidal silica in cement composites. Investigation is focused primarily on selected properties of cement pastes and mortars with colloidal silica content. Two selected types of colloidal silica (particles with average size of 14 nm) have been used as a cement addition and partial replacement of cement, respectively. The experimental program for cement pastes with colloidal silica included tests for isothermal calorimetry (the study of cement hydration) and thermal analysis (determining the portlandite content). Hardened cement pastes have been studied through measurements of compressive strength. The microstructure was examined by scanning electron microscopy. Hardened mortars with colloidal silica have been studied through measurements of compressive strength, flexural strength, modulus of elasticity and fracture mechanics parameters. Fracture mechanics tests show that 5 % and 20 % addition of colloidal silica can enhance after 28 days of curing fracture energy up to 18,4 % and 32,7 %, respectively. For the compressive strength enhancing effect of colloidal silica, it was found to be more pronounced in the early age, while rate of strength gain can be lower than the control in the later ages. Our investigations revealed that the silica sol will coagulate immediately when the cement is mixed into the water containing sol. The ionic composition of pore fluid significantly influences the stability of colloidal silica and lead to their aggregation. After additional tests it has been found that small addition of calcium hydroxide greatly improved the compressive strength of the resulting cement pastes with colloidal silica content. Addition of calcium hydroxide in conjunction with modified cement paste preparation can enhance compressive strength after 3 days of curing up to 64,4 % in comparison with the blank paste.

This work deals with the use of inorganic nanofibers in refractory castables. The thesis describes some of the results of previously conducted research on nanofibers. Also description of nanofibres, production and distribution. The experimental part is focused on studying the interaction of Al2O3 and SiO2 nanofibres with aluminate cement. The main subject of investigation is a dispersion of nanofibers using a surfactant and ultrasonication.

The main goal of the dissertation is to design and verify coatings for surface finish of cement bonded particleboards with the aim of improvement of their resistance against the unfavorable influences of the exterior taking into account the aesthetic function of the surface finish.

L'ettringite Ca6Al2(SO4)3(OH)12.26H2O est l'un des principaux produits d'hydratation des ciments et malgré l'importance de ce composant dans la chimie des ciments, les lois gouvernant ses processus de précipitation ont été très peu étudiées. Ce travail de thèse a donc été centré entièrement sur l'étude de l'ettringite et sur ses mécanismes de germination-croissance.La précipitation d'ettringite a d'abord été étudiée seule à partir de solutions ioniques sursaturées. Les expériences ont été menées dans le but d'étudier séparément les processus de nucléation et de croissance. La Théorie Classique de la Nucléation a été appliquée et a permis la détermination de l'énergie interfaciale de l'ettringite. Une description globale du processus de précipitation de l'ettringite a pu être proposée. Il est apparu que l'ettringite est un hydrate se formant très facilement, de par sa faible énergie interfaciale, et présentant une vitesse de formation élevée dès que ses ions constitutifs sont présents en solution. Après la nucléation primaire homogène, lorsque la quantité de cristaux déjà formés est encore faible, la vitesse de précipitation de l'ettringite dépend surtout du degré de sursaturation de la solution. Lorsque la surface cristalline devient significative, son influence provoque une augmentation de la vitesse de précipitation et des processus simultanés de nucléation secondaire et de croissance ont été mis en évidence.Dans un second temps, la formation d'ettringite a été étudiée lors de l'hydratation d'un système C$_3$A/sulfate de calcium, choisi pour se rapprocher des réactions ayant lieu dans un ciment Portland. Les expériences conduites ont permis de montrer qu'une concentration grandissante en ions sulfate (et en ions calcium) dans la solution accélérait la précipitation d'ettringite. Les résultats obtenus en première partie concernant la facilité et la rapidité de la précipitation d'ettringite seule à partir de solutions sursaturées semblent également valables dans le cas d'une formation d'ettringite lors de l'hydratation d'un système C3A/CaSO4. / Ettringite Ca6Al2(SO4)3(OH)12.26H2O is one of the main hydration products of cements but despite the importance of this compound for cement chemistry, laws governing its precipitation processes have been poorly studied. This PhD thesis was entirely focused on the study of ettringite and on its nucleation-growth mechanisms.Ettringite precipitation was first studied alone from supersaturated ionic solutions. Experiments were designed in order to study separately processes of nucleation and growth. The Classical Theory of Nucleation was applied and allowed the determination of the interfacial energy of ettringite. A global description of ettringite precipitation process has been suggested. It appeared that ettringite is an easily formed hydrate, because of its low interfacial energy, presenting a high precipitation rate as soon as its constitituve ions are present in solution. After primary homogeneous nucleation, when the quantity of already formed crystals is still low, precipitation rate of ettringite mainly depends on the supersaturation degree of the solution. When the crystalline surface gets significative, it provokes an increase of precipitation rate and processes of secondary nucleation and growth have been identified.Then, formation of ettringite during the hydration of a C$_3$A/calcium sulfate system, chosen to get closer to chemical reactions happening in a Portland cement, was studied. Conducted experiments helped prove that a growing concentration of sulfate ions (and of calcium ions) in solution was speeding up ettringite precipitation. Obtained results about the ease and speed of ettringite precipitation alone from supersaturated solutions seem also valid in the case of ettringite formation during the hydration of a C$_3$A/CaSO$_4$ system.

Magister Scientiae Dentium - MSc(Dent) / CAD/CAM crowns have become popular due to the many advantages associated with this technology. Optimal bonding adhesion is crucial for the durability of these indirect restorations and many factors influence this crucial step. Currently, there is no consensus or evidence-based guidelines on the best adhesion protocol for CAD/CAM crowns fabricated from hybrid materials. This study was aimed at investigating the influence of three types of resin cements on the shear bond strength of a hybrid CAD/CAM material in vitro.

The need for economical, sustainable, safe, and secure shelter is an inherent global problem and numerous challenges remain in order to produce environmentally friendly construction products which are structurally safe and durable. The use of sisal, a natural fiber with enhanced mechanical performance, as reinforcement in a cement based matrix has shown to be a promising opportunity. This work addresses the development and advances of strain hardening cement composites using sisal fiber as reinforcement. Sisal fibers were used as a fabric to reinforce a multi-layer cementitious composite with a low content of Portland cement. Monotonic direct tensile tests were performed in the composites. The crack spacing during tension was measured by image analysis and correlated to strain. Local and global deformation was addressed. To demonstrate the high performance of the developed composite in long term applications, its resistance to tensile fatigue cycles was investigated. The composites were subjected to tensile fatigue load with maximum stresses ranging from 4 to 9.6 MPa at a frequency of 2 Hz. The composites did not fatigue below a maximum fatigue level of 6 MPa up to 106 cycles. Monotonic tensile testing was performed for composites that survived 106 cycles to determine its residual strength.

ROBATEL Industries conçoit et fabrique des emballages pour matières fortement radioactives. Des matériaux de protection neutronique et thermique (PNT) sont utilisés dans ces emballages afin d’assurer la capture des neutrons et de limiter l’augmentation de la température des matières radioactives en cas d’incendie. Ces PNT sont constitués d’une matrice cimentaire ou de plâtre auxquels sont ajoutées des charges minérales ou organiques. Une charge minérale, la colemanite, permet la capture des neutrons grâce à sa teneur élevée en bore, après que l’hydrogène contenu dans les PNT les ait ralentis.Le premier enjeu de cette thèse a été de mettre au point des méthodes d’analyse élémentaire afin de caractériser l’homogénéité chimique des PNT, qui est cruciale, notamment pour le bore. Une technique de mise en solution et deux techniques de dosages ont ainsi été développées. Une autre partie importante de la thèse concerne la caractérisation des propriétés thermiques et mécaniques des PNT. D’un point de vue thermique, des mesures de chaleur de réaction, de capacité calorifique et de conductivité thermique ont été menées pour déterminer la quantité de chaleur (enthalpie) absorbée par le matériau en cas d’incendie. D’un point de vue mécanique, des essais de compression et de flexion ainsi que des essais ultrasonores ont été réalisés afin d’évaluer les valeurs des contraintes à la rupture et les modules d’élasticité des PNT. Au-delà de ces caractérisations, l’amélioration des formulations des PNT existantes et surtout la mise au point de nouvelles formulations sont au coeur de ce travail. Deux plans de mélange ont ainsi été réalisés afin d’enrichir les PNT en bore et en hydrogène tandis qu’un autre a permis l’augmentation de la fluidité d’un PNT grâce à l’ajout d’un superplastifiant. La dernière partie de la thèse a concerné l’étude de nouveaux ciments, les sulfoalumineux, qui présentent des caractéristiques intéressantes étant donné que leurs hydrates sont riches en hydrogène. Pour ces trois nouvelles familles de PNT à base de sulfoalumineux, le retard de prise induit par le bore a été limité. / ROBATEL Industries company designs and products packages for highly radioactive materials. Neutron and thermal protection materials (PNT) are used in those packages to catch neutrons and to limit the increase of temperature due to radioactive materials in case of fire. These PNT are composed of a cement or a gypsum-based matrix with mineral or organic fillers. Once the neutrons have been slowed down by the hydrogen contained in the PNT, a mineral filler named colemanite enables the neutron capture thanks to its high content of boron.The first goal of this thesis is to develop analytical chemistry techniques to check the chemical homogeneity of the PNT, which is crucial, particularly for boron. A dissolution method and two determination techniques have been developed. Another important topic in this thesis is characterization of thermal and mechanical properties. Thermal characterizations include heat of reaction, heat capacity and thermal conductivity measurements to determine the total heat absorbed by the PNT in case of fire. Mechanical characterizations include compression, bending and ultrasonic tests in order to evaluate stress to rupture and elastic moduli of PNT. Beyond the characterizations, the aim of this thesis is to improve pre-existing formulas of PNT and most importantly to propose new formulas. Two mixture designs have been carried out to increase the boron and the hydrogen concentrations of PNT. Another mixture design allowed enhancing the fluidity of a PNT using a superplasticizer. The last part of the thesis deals with the study of new cements called sulfoaluminous that show interesting properties because their hydration products are rich in hydrogen. For these three new PNT families, the increase of the setting time of cement due to boron has been restricted.

OBJECTIVE: The aim of this in-vitro study is to assess the effect of cyclic loading fatigue on failure load of CAD/CAM cement-retained implant crowns and screw-retained implant crowns with screw access holes sealed with composite or Enamic inlay. MATERIALS AND METHODS: For the screw-retained implant crowns, Ivoclar e.max and Vita Enamic CAD/CAM (n=44 for each material) and Enamic inlays (n=44) were designed using Sirona in-Lab software system (SW4 4.2.5) and milled using CEREC in-Lab MC XL. All the prepared e.max and Enamic crowns were cemented to Sirona TiBase (B O 4.1 L) using Ivoclar hybrid multilink cement. The access holes were sealed either by using composite or and Enamic inlay (n=22 for each group). For cement-retained implant crowns, Ivoclar e.max, Vita Enamic, and Vita Mark II CAD/CAM (n=20 for each material) and Enamic and Zirconia abutments (n=40 for each group) were designed using Sirona in-Lab software system (SW4 4.2.5) and milled using CEREC in-Lab MC XL. All the prepared zirconia and Enamic abutments were cemented to Sirona TiBase (B O 4.1 L) using Ivoclar hybrid multilink cement. Then, all prepared Ivoclar e.max, Vita Enamic, and Vita Mark II crowns were cemented to the abutments using Multilink Automix cement. After cementation, 10-12 specimens from each group (both screw and cement-retained) were subjected to a static load to failure test in a universal mechanical testing machine (Instron 5566A). The mean failure load for each group was calculated. The other 10 specimens for each group were subjected to cyclic loading fatigue under 40% of static failure load for 50,000 and 100,000 cycles. After cyclic loading, the surviving specimens were tested for static failure load. The comparison of failure load between tested groups was analyzed by one-way ANOVA using JMP Pro 13 with α=0.05. RESULTS: For IPS e-max CAD screw-retained implant crowns, there was a significant difference in the failure load at static and after cyclic fatigue for 50,000 cycles, but no significant difference between static and after cyclic fatigue for 100,000 cycles. For Vita Enamic crowns, there was no significant difference in the failure load at static and after cyclic fatigue for 50,000 cycles and 100,000 cycles. There was a significant difference in the failure load between screw-retained implant crowns sealed with composite and those sealed with Enamic inlay. For IPS e-max CAD /Zr abutment and Vita Mark II/ Enamic abutment cement-retained implant crowns, there was a significant difference in the failure load at static and after cyclic fatigue for 100,000 cycles. For Vita Enamic /Zr abutment cement-retained implant crowns, there was no significant difference in the failure load at static and after cyclic fatigue for 100,000 cycles. CONCLUSION: The screw-retained implant crowns sealed with composite had higher failure load than those sealed with Enamic inlay. The cyclic fatigue has an effect on IPS e.max CAD screw-retained implant crowns, IPS e-max CAD /Zr abutment and Vita Mark II/ Enamic abutment cement-retained implant crowns. The cyclic fatigue has no effect on Vita Enamic screw-retained implant crowns and Vita Enamic/ Zr abutment cement-retained implant crowns.

This study will explore if, and if so how, a transition into a more sustainable and eco-friendly ordinary portland cement can be made, without damaging its fundamental strengths and properties. The core concept essence of this degree project focuses on a comparison between four central properties of fly ash in portland cement with those of ordinary portland cement: the chloride-induced penetration, alkali reactivity, frost resistance and strength. The study will attempt to describe what measures the concrete industry are taking on the path towards a non-fossil future, following a sort of a roadmap. The process of making concrete is a major contributor to CO2 emissions, and the process is energy-intensive. The changing climate is affecting every living thing on this planet in a negative way, and in the end, there will be devastating consequences for all the different sectors of society if we cannot change our ways of using natural resources. Because of its current carbon footprint, the construction industry has a long way to go before reaching its non-fossil vision. A literature study was carried out to determine if concrete’s current properties and solidity could be retained when making a non-fossil concrete, or at least a more eco-friendly one. The alternative admixture fly ash decreased the amount of water needed and reduced the amount of clinker particles used in making concrete. This leads to a decreased usage of fossil fuel in the production process, without actually affecting the actual life span of the concrete negatively. In fact, use of fly ash improves the concrete a longer life span. Another vital measurement that can be taken is to use the technique called CCS, which leads to a decreased amount of pollution in the production process. The Swedish construction industry is determined to reach their non fossil vision. There is a strong belief that a life without being dependent on fossil fuel is a better life, and this will hopefully lead to a global race towards achieving sustainability. The result of this study shows that the current development within the industry is eco-positive and will contribute towards a more sustainable future for the concrete industry.