This diploma thesis is focused on long term monitoring of thermodynamic stability of ettringite under selected conditions and its possible destabilization or transformation into another AFt phase, especially thaumasite. Ettringite samples were made in two ways, by hydrating the yeelimite in the system with the alite and by addition of aluminium sulphate and calcium hydroxide.

This master’s thesis is focused on the effect of mixing water pH value on hydration and mechanical properties of cement composites based on portland cement. Source material was CEM I 42,5 R. Hydration process was analyzed by isoperibolic calorimetry, X-ray diffraction analysis and differential thermal analysis. Compressive and flexural strength was examined as mechanical properties. The samples microstructure was observed by scanning electron microscopy. Influence of mixing water pH value on flexural and compressive strength, retardation of hydration and ratio of individual phases was shown.

Diploma thesis discusses about design composition and firing process modification of belite clinker. It also deals with the summary of knowledge about chemistry and production technology of portland cements with respect to its ecology and economy.

The thesis is oriented on monitoring of hydration process of portland cement based on fluidized bed ash, firstly on investigation of AFt phases, mainly ettringite and thaumasite. Specific aim of the task is to prepare the scheme of these minerals synthetic preparation and to verify their laboratory preparation by different ways, using methods of RTG-diffraction analysis and scanning electron microscopy.

Heavy-metal contamination in soils has become a serious environmental problem. Among all metals, excessive amount of zinc was released to soils over the years. Zinc is not only toxic to human being, but also to plants. High concentration of zinc is extremely phytotoxic. Currently, the most popular method to remediate heavy-metal contaminated soils is stabilization/solidification (S/S) technique as it is cheaper, faster and more effective to remediate heavy metals than other remediation methods. Portland cement is the most-used binder in S/S technique. However, the production of Portland cement has released a significant amount of carbon dioxide, which strongly contributes to global warming. In addition, zinc retards the setting and hydration of Portland cement, which would require more Portland cement to remediate zinc-contaminated sites. Therefore, researchers are looking for new materials to improve the performance of Portland cement in zinc-contaminated soils. In recent years, the application of graphene-based materials in concrete had proved to be effective. Due to relative cost-effectiveness and comparable properties, multi-layer graphene, known as graphene nanoplatelets, may show a promising potential in construction. Moreover, research has reported that graphene nanoplatelets can be exfoliated from graphite and potentially scaled up for full-scale applications. At present, there is no application of graphene nanoplatelets in the S/S of contaminated soils and the roles of graphene nanoplatelets in cement-stabilized zinc-contaminated clay remained unknown. In this research, graphene nanoplatelets were dispersed in solution with a high-shear mixing apparatus. Dispersed graphene nanoplatelets solution was then applied to zinc-contaminated soil along with cement. To evaluate the efficacy of this S/S method, various influencing factors such as mixing sequence, graphene nanoplatelets content, zinc content, cement content, and curing time were studied. An optimum graphene nanoplatelets content was determined through the unconfined compressive strength (UCS) of the stabilized/solidified samples. It was found that at the optimum content, the unconfined compressive strength of cement-stabilized zinc-contaminated clay was improved by 22.3% with the addition of graphene nanoplatelets. Also, graphene nanoplatelets were effective at moderate zinc content and low cement content. Graphene nanoplatelets accelerated cement hydration effectively at early ages. Microstructural analyses indicated that more hydration products were developed in samples with graphene nanoplatelets. At current stage, it is still expensive to apply graphene nanoplatelets in S/S technique; however, it is possible to exfoliate graphite into graphene nanoplatelets in future research. / Graduate / 2022-05-12

The purpose of this research was to investigate the effects of reclaimed asphalt pavement (RAP) content and cement content on the strength and durability of recycled aggregate base materials. Specifically, the unconfined compressive strength (UCS) and final dielectric value in the Tube Suction Test (TST) were measured in a full-factorial experimental design including five RAP contents, five cement contents, and three replicate specimens of each possible treatment. Specimen mixtures consisted of 0, 25, 50, 75, or 100 percent RAP and 0.0, 0.5, 1.0, 1.5, or 2.0 percent Type I/II Portland cement. Both the RAP and base materials were sampled from the I-84 pavement reconstruction project performed in Weber Canyon near Morgan, Utah, during the summers of 2004 and 2005. The laboratory testing procedures consisted of material characterizations, specimen preparation, and subjection of the specimens to strength and durability testing, and the data were evaluated using analysis of variance (ANOVA) testing. Both the RAP and base materials included in this research were determined to be non-plastic, and the AASHTO and Unified soil classifications for the RAP material were determined to be A-1-a and SM (well-graded sand with gravel), respectively, and for the base material they were A-1-a and SW-SM (well-graded sand with silt and gravel), respectively. The optimum moisture contents (OMCs) for the blended materials were between 5.6 and 6.6 percent, and maximum dry density (MDD) values were between 129.7 and 135.5 lb/ft3. In both cases, decreasing values were associated with increasing RAP contents. The results of the ANOVA performed on the UCS data indicate that UCS decreases from 425 to 208 psi as RAP content increases from 0 to 100 percent and increases from 63 to 564 psi as cement content increases from 0.0 to 2.0 percent. Similarly, the final dielectric value decreases from 14.9 to 6.1 as RAP content increases from 0 to 100 percent and decreases from 14.0 to 5.8 as cement content increases from 0.0 to 2.0 percent. With design criteria requiring 7-day UCS values between 300 and 400 psi and final dielectric values less than 10 in the TST, the results of this research suggest that milling plans should be utilized to achieve RAP contents in the range of 50 to 75 percent, and a cement content of 1.0 percent should be specified for this material. Cement contents less than 1.0 percent are not sufficient to stabilize the material, and greater cement contents may cause cracking. Because control of the actual cement content in the field depends on the contractor's equipment and skill, inspection protocols should be implemented during construction to ensure high-quality work. Additional recommendations are associated with the construction process. The specimens prepared in this research were compacted to relative densities of 100 percent using modified Proctor energy. Therefore, field compaction levels must approach these density values if the same material properties are to be achieved. In addition, all specimens tested in this study were cured at 100 percent relative humidity. Following compaction in the field, cement-treated layers should be moistened frequently during the first few days after construction or promptly sealed with a prime coat or wearing surface to ensure that the cement continues to hydrate. Variability in RAP and cement contents should also be minimized to achieve consistent material properties.

Portland cement concrete, the most widely used manufactured material in the world, is made primarily from water, mineral aggregates, and portland cement. The production of portland cement is energy intensive, accounting for 2% of primary energy consumption and 5% of industrial energy consumption globally. Moreover, Portland cement manufacturing contributes significantly to greenhouse gases and accounts for 5% of the global CO2 emissions resulting from human activity. The primary objective of this research was to explore methods of reducing the environmental impact of cement production while maintaining or improving current performance standards. Two approaches were taken, 1.) incorporation of waste materials in portland cement synthesis, and 2.) optimization of an alternative environmental friendly binder, calcium sulfoaluminate-belite cement. These approaches can lead to less energy consumption, less emission of CO2, and more reuse of industrial waste materials for cement manufacturing. In the portland cement part of the research, portland cement clinkers conforming to the compositional specifications in ASTM C 150 for Type I cement were successfully synthesized from reagent-grade chemicals with 0% to 40% fly ash and 0% to 60% slag incorporation (with 10% intervals), 72.5% limestone with 27.5% fly ash, and 65% limestone with 35% slag. The synthesized portland cements had similar early-age hydration behavior to commercial portland cement. However, waste materials significantly affected cement phase formation. The C3S–C2S ratio decreased with increasing amounts of waste materials incorporated. These differences could have implications on proportioning of raw materials for cement production when using waste materials. In the calcium sulfoaluminate-belite cement part of the research, three calcium sulfoaluminate-belite cement clinkers with a range of phase compositions were successfully synthesized from reagent-grade chemicals. The synthesized calcium sulfoaluminate-belite cement that contained medium C4A3 S and C2S contents showed good dimensional stability, sulfate resistance, and compressive strength development and was considered the optimum phase composition for calcium sulfoaluminate-belite cement in terms of comparable performance characteristics to portland cement. Furthermore, two calcium sulfoaluminate-belite cement clinkers were successfully synthesized from natural and waste materials such as limestone, bauxite, flue gas desulfurization sludge, Class C fly ash, and fluidized bed ash proportioned to the optimum calcium sulfoaluminate-belite cement synthesized from reagent-grade chemicals. Waste materials composed 30% and 41% of the raw ingredients. The two calcium sulfoaluminate-belite cements synthesized from natural and waste materials showed good dimensional stability, sulfate resistance, and compressive strength development, comparable to commercial portland cement. / text

For repairing concrete transportation infrastructure, such as pavements and bridges, much importance is placed on early-age strength gain as this has a major impact on scheduling and opening to traffic. However, the long-term performance and durability of such repair materials are often not satisfactory, thus resulting in future repairs. This research project focuses on the evaluation of the durability of various rapid-setting cementitious materials. The binders studied in this project include calcium aluminate cement (CAC), calcium sulfoaluminate cement (CSA), Type III portland cement, alkali-activated fly ash (AAFA) , and various prepackaged concrete materials. In addition, selected CAC and CSA mixtures were further modified with the use of a styrene-butadiene latex. The durability aspects studied include freezing-and-thawing damage and the implications of air entrainment in these systems, alkali-silica reaction, sulfate attack, and permeability of the concrete matrix and potential corrosion. / text

Les mélanges de ciment sulfoalumineux et de ciment Portland sont des liants hydrauliques innovants permettant de moduler les propriétés des bétons, telles que la vitesse de montée en résistance ou la stabilité dimensionnelle. Les performances du liant peuvent ainsi être ajustées pour de nombreuses applications. Au-delà de cet avantage, les émissions de dioxyde de carbone liées à la production du ciment sulfoalumineux sont significativement réduites comparées à celles du ciment Portland traditionnellement utilisé. La diversité des propriétés de ces liants résulte de la variété des mélanges pouvant être réalisés à partir des deux constituants de base. Chaque mélange présente alors une cinétique d'hydratation et des propriétés qui lui sont propres. Par exemple, certains liants sont expansifs mais présentent une montée en résistance progressive, tandis que d'autres sont stables dimensionnellement alors que leur résistance stagne après quelques jours d'hydratation. L'identification et le contrôle des paramètres à l'origine de ces comportements sont donc nécessaires pour garantir des propriétés spécifiques à un usage donné : chape, mortier de réparation, élément préfabriqué, etc. C'est l'objectif de cette étude qui s'attache à déterminer la cinétique, la minéralogie et les propriétés associées à l'hydratation de trois mélanges contenant 85 %, 70 % et 40 % de ciment Portland. Les essais entrepris ont aussi permis d'aboutir à une modélisation thermodynamique des mécanismes d'hydratation. L'impact de la composition du ciment Portland est également étudié. Enfin, il est montré que l'anhydrite et la chaux sont deux leviers qui modifient radicalement le processus d'hydratation et permettent ainsi d'adapter les propriétés d'un mélange aux exigences de son utilisation / Blends of ordinary Portland cement and sulfoaluminate cement are innovative hydraulic binders allowing control of concrete properties such as hardening speed or dimensional stability for specific applications. Moreover, carbon dioxide emissions linked to sulfoaluminate cement are significantly reduced compared to ordinary Portland cement. The binder properties can be adjusted due to the diversity of blends conceivable with these two constituents. Each blend has its own hydration kinetic and properties. For example, some blends are expansive and the hardening is progressive whereas other mixtures are dimensionally stable but their strength stagnates after few days. Identification and control of the parameters responsible of these comportments are necessary in order to guaranty specific properties for each application: screed, repairing mortar, etc. This is the aim of this study which described the hydration kinetic, the properties and composition of three blends containing 85 %, 70 % and 40 % of Portland cement. These experiments are completed by thermodynamic modeling of the hydration mechanisms. The effect of the Portland cement composition has also been tested. Finally, it's shown that anhydrite and calcium hydroxide are two key parameters which modify radically the hydration process and allow the properties adjustment required for the blend used

O objetivo deste trabalho é avaliar o microclima interno de escamoteadores com diferentes formulações de placas cimentícias para o piso, aquecido com resistência elétrica. As placas de argamassa de cimento Portland tiveram por base o aproveitamento de resíduos agropecuários (cama sobreposta de suíno, fibra curta de sisal e casca de arroz) na sua confecção, em busca da melhoria nas propriedades físicas e mecânicas das placas. Essas matérias-primas serão utilizadas como material alternativo, na busca do reaproveitamento destes resíduos, que, na maioria das vezes, são descartados de forma errônea, prejudicando o meio ambiente. Esses resíduos foram caracterizados de forma a analisar sua potencialidade para a confecção das placas para piso de abrigo escamoteador. Foram confeccionados corpos-de-prova com seis diferentes tipos de formulações: referência de cimento Portland (C1), de CCSS em substituição a 30% em massa do cimento Portland (C2); de CCSS substituindo 30% de cimento Portland e fibras curtas de sisal substituindo 1,7% da massa da areia (C3); de CCSS substituindo 30% de cimento Portland e com casca de arroz substituindo 4% em massa de areia (C4); de cimento Portland com casca de arroz substituindo 4% da areia (C5); de cimento Portland com fibras curtas de sisal substituindo 1,7% da massa da areia (C6). Com base nos resultados dos ensaios físicos e mecânicos, as melhores formulações (C2, C3 e C4) foram escolhidas para a confecção das placas para o abrigo escamoteador. Para caracterização do ambiente, foram utilizados data-loggers para coleta de variáveis para determinação dos índices de conforto térmico: índice de temperatura de globo e umidade (ITGU), carga térmica radiante (CTR), entalpia (H), além dos índices analisou-se também a temperatura ambiental (TA) e a umidade relativa (UR). Os dias com menor valor de entalpia (H) foram considerados para análise comparativa dos índices de conforto, e os abrigos escamoteadores foram submetidos a quatro diferentes temperaturas de resistência (30, 35, 45 e 55 ºC). Os valores recome ndados para ITGU, CTR, H, TA e UR foram observados nos três diferentes tratamentos com a temperatura da resistência elétrica acima de 35ºC. Os resultado s obtidos validaram o destino alternativo a CCSS, a fibra de sisal e a casca de arroz, como materiais viáveis para utilização em placas de piso para abrigos escamoteadores com aceitável desempenho térmico, físico e mecânico. / The objective of this study is to evaluate the internal microclimate of piggy\'s houses with different formulations of cementitious boards for the floor, warmed with electrical resistance. The boards of ordinary Portland cement mortar were based on the use of agricultural residues (swine deep bedding, short-fiber sisal and rice husk) in its production, in search of improvement in physical and mechanical properties of the plates. These raw materials will be used as alternative materials searching reuse of waste, which in most cases are disposed of wrongly, harming the environment. These wastes were characterized in order to assess was potential for making the plates for floor piggy\'s houses. Samples were prepared with six different types of formulations: reference ordinary Portland cement (OPC) (C1), replacement of OPC by 30% by weight of ashes swine deep bedding (ASDB) (C2); replacement of OPC by 30% of ASDB and fiber short sisal replacing 1.7% of the mass of sand (C3); replacement of OPC by 30% of ASDB and rice husk replacing 4% by mass of sand (C4); OPC with rice husk replacing 4% of the sand (C5); OPC with short sisal fibers replacing 1.7% of the sand (C6). Based on the results of the mechanical and physical tests, the best formulations (C2, C3 and C4) were chosen for the preparation of the floor plates in the piggy\'s houses. To characterize the environment, data-loggers were installed for the collection of variables to determine the thermal comfort indices: black globe temperature and humidity index (BGHI), radiant heat load (RHL), enthalpy (H), ambient temperature (AT) and relative humidity (RH). The days with lower values of enthalpy (H) were considered for comparative analyses of the comfort indices, and piggy\'s houses were subjected to four different temperatures of electric resistance (30, 35, 45 and 55ºC). The recommended v alues for BGHI, RHL, H, AT and RH were achieved in the three different treatments with temperature of electric resistance above 35ºC. The results validat ed the alternative destination to ASDB, sisal fiber and rice husks as viable material for use in floor plates piggy\'s houses with acceptable thermal, physical and mechanical performance.