This thesis aims to burn raw material with a lower content of carbonate component for the production of Portland cement. Substitution of carbonate component is done by fluidized fly ash. The model cements are tested of basic technological properties and the hydration process is observed.

The Ph.D. thesis deals with the preparation of highly hydraulic binders based on roman cement. Roman cement (natural cement) is recently not available on the market due to uneconomic production of such a specific binder. On the other hand there is a big lack of information on this hydraulic binder. These results in failure in meeting the basic principle of modern approaches to restoration of historical buildings or monuments made of such kind of materials, which is such, that the materials used for restoration should be compatible with original material. Recognition of the processes of roman cement preparation based on progressive methods of study can provide substantial information for more efficient raw material selection or even for nontraditional utilization, for example for artworks. This work hence is aimed at studying and selection of traditional natural as well as nontraditional raw materials such as clay. This work also studies the preparation of highly hydraulic binders based on roman cement and the kinetics of burning and hydration processes

The Master’s thesis is focused on a study of the effect of increased content of heavy metals present in a raw meal on the formation and properties of prepared clinker and acquired cement. Main attention is devoted to changes on the physical, mechanical, microstructural and hydration properties. The theoretical part contains an overview of clinker minerals occurring in Portland cement including the possibility of incorporation of heavy metals into their structure and affecting the properities of the cement. In the experimental part, there is compared the effect of heavy metal oxides on the composition and hydration properties of portland clinker and physical-mechanical and microstructural properities of cement pastes prepared from this clinker.

The goal of this work was to create a method for improving the dispersion of silica fumes for use in high performance concrete. Traditional methods used to design and manufacture high performance concrete emphasize the removal of coarse aggregates. Use of specially sorted fine aggregates at relatively low doses, the use of super-plasticizers and siliceous excrement. The low water content was achieved by using superplasticizer on a polycarboxylate basis. The standard ultrasound technology found in each laboratory was selected for the dispersion of silica fume. For experiments were we used dry silica fume powder and aqueous stabilized suspension. For comparison, were prepared different mixtures which showed the effects of the treatment prior to the use of silica fume.

The thesis deals with the study and the characterization of bypass dusts from the cement plants. The aim of the thesis is to search for the possibilities of the usage of that secondary product by means of the cement production. The thesis focuses mainly on the determination of the amount of soluble substances in the dusts, the dependence of dissolution of the soluble share on water – dust ratio, the dependence of dissolution time on the yield of the soluble share and the influence of the temperature on the yield. The physical and chemical properties of the investigated samples taken from several cement plants in the Czech Republic and Slovakia were found out by using the following methods: by TG/DTA analysis, particles size by laser diffraction, phase composition of raw materials, treated raw materials and evaporation residues by X-ray diffraction. It was further investigated whether there was a link between finesse of the particles and the content of soluble substances (chlorides). This was accomplished by classification of the bypass dusts as fine and coarse fraction on the air cassifier with the target parameter X50 1 m. The aim of the classification was to find out whether some of the fractions carry majority share of some of components.

Orientador: Paulo César Lodi / Resumo: A proposição de uso de materiais alternativos na construção civil que busquem reduzir a produção de resíduos ou utilizar resíduos anteriormente gerados mostra-se cada vez mais necessária, uma vez que a indústria da construção civil situa-se hoje como uma das maiores consumidoras de matérias-primas naturais. Dessa forma, este trabalho avaliou os efeitos que a inclusão de tiras poliméricas de polietileno tereftalato (PET) cortadas a partir de garrafas plásticas descartadas, e de cimento geram na resistência mecânica de um solo arenoso retirado da região de Bauru (SP). Foram realizados ensaios de resistência uniaxial em solo puro e com a inclusão aleatória de tiras de PET em diferentes comprimentos e porcentagens. Além dos ensaios de resistência não confinada, foram realizados também ensaios de compactação com adições de cimento e com adições de tiras de PET, a fim de se analisar os efeitos destas inclusões aos parâmetros compactação da matriz arenosa. Por fim, foram realizados também ensaios de cisalhamento direto em compósitos de solo-tira, solo-cimento e em compósitos de solo-cimento-tira, tornando possível a avaliação dos efeitos individuais de cada tipo inclusão na resistência ao cisalhamento da matriz. Em relação à resistência uniaxial notou-se o aumento da resistência da matriz arenosa devido à inclusão de tiras, independente do tamanho e percentagens analisadas. Quanto aos ensaios de cisalhamento direto, a adição de cimento foi efetiva aumentando tanto a coesão, quanto o... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The proposition of using alternative materials in construction that seek to reduce waste production or use previously generated waste is becoming increasingly necessary, as the construction industry is today one of the largest consumers of natural resources. Thus, this work evaluated the effects that the inclusion of polyethylene terephthalate (PET) strips cut from waste plastic bottles, and cement generate on the mechanical strength of a sandy soil from Bauru (SP). Unconfined strength tests were performed in pure soil and with the random inclusion of PET strips in different lengths and percentages. In addition to the unconfined strength tests, were also performed compaction tests with cement additions and with addition of PET strips, in order to analyze the effects of these inclusions on the sandy soil. Finally, direct shear tests were also performed on soil-strip, soil-cement and soil-cement-strip composites, making it possible to evaluate the individual effects of each inclusion on the shear strength of the analyzed soil. Regarding the uniaxial resistance, the soil resistance increased due to the inclusion of strips, regardless of the size and percentages analyzed. As for the direct shear tests, the cement addition was effective increasing both the cohesion and the soil friction angle in large proportions. The addition of strips to the soil-cement composite had its most pronounced effect on increasing soil cohesion, often reducing the friction angle. In general, the additi... (Complete abstract click electronic access below) / Mestre

Magister Chirurgiae Dentium (MChD) / Background: This study aimed to determine the association between dimensional change and surface roughness (Ra) of Vitremer, Activa and Cention N after immersing them into two different media: acidic and artificial saliva media for the period of a year. Measurements were made at 10 time intervals during the observation period. Methodology: This was a quantitative and qualitative study. For the quantitative part, a total of 60 specimens were tested, 20 specimens for each material. The 20 specimens were further divided into 10 specimens. Ten were immersed in acidic media and the rest in saliva media. A measurement of the weight, height, and Ra was carried out as follows: day 0, day 1, day 2, day 7, day 21, day 28, day 60, day 90, day 180 and day 365. Scanning electron microscopy (SEM) was used to examine the surface of each material qualitatively pre and post immersion in the two media. For fluoride measurements, an additional five samples from each material were left suspended in the de-ionized water by the use of dental floss. The materials were moved to new specimen jars after the completion of day 1, 2, 3, 4, 5, 6, 7, 14, 21 and 28. All the specimen jars had been kept for the fluoride measurements. Results: Non-parametric tests were used to analyze the data. Linear regression analysis was used to measure the association between weight, height or surface roughness (Ra) and immersion time for a year. The result of this test showed that Vitremer had a significant association between the weight (p = 0.000), height (p = 0.007) and Ra (p = 0.001) when it was immersed in acidic media. On the other hand, when Vitremer was immersed in saliva media, only the weight variable showed a significant association (p = 0.002). For Cention N, significant association was found for only Ra when immersed in acidic media (p = 0.000). Finally, for Activa, all the studied associations; the weight, height and Ra in both media were found to be insignificant. For saliva media, there was a significant weight change between the three materials during all 10 periods of time (p = 0.000). In the first six months, Cention N demonstrated a significant increase in weight changes followed by Vitremer, then Activa. Yet, after a year, the difference between Cention N and Vitremer became insignificant and Activa showed the least weight changes. There was not a significant difference between the materials in terms of height and Ra measurements. The fluoride experiment was not successful due to technical issues during pH measurements of the collected solutions. For comparison of the studied parameters between the three materials, the Kruskal-Wallis test was used. In acidic media, there was a significant difference between the materials in term of weight change in 10 periods of time (p = 0.000). In particular, after a two month period, Cention N had the highest weight, followed by Vitremer and then by Activa. The difference between Vitremer and Activa became insignificant throughout the rest of the experimental time frame. All the height measurements between the three materials were found to be insignificant except for day 365 (p = 0.048), where both Activa and Cention N were found to be significantly higher than Vitremer. For the Ra comparison, in the first two weeks, particularly day 1, 7 and 14, Cention N had significantly the lowest Ra among the other materials. As the three materials aged in the acidic media (day 180), Vitremer had significantly the highest Ra values. Cention N showed higher Ra values than Activa; nonetheless this difference was not significant. The SEM images showed loss of some particles in all post-experimental images of the materials in acidic media. Vitremer showed the widest cracks with the loss of fillers. In saliva media, there was also loss of particles but to a lesser extent than in acidic media. Yet, the post-experimental image of Activa in saliva resembled the pre-experimental one. Conclusion: Within the limitations of the study, the best material to resist Ra from prolonged acidic attack was Activa followed by Cention N and then Vitremer. Except for Vitremer, no significant changes in the Ra of the other materials were detected when the three materials were immersed in saliva media in the long term. In acidic media Vitremer tended to lose weight and height faster than Cention N and Activa over a year. Cention N is the best material to resist dimensional change. However, in artificial saliva Vitremer gained water rapidly. Activa did not absorb a lot of water and did not reject a lot of water; Activa demonstrated good dimensional stability and this property may be beneficial when compared to the other two materials tested. The clinical significance of the study: All the materials studied were subjected to dimensional and Ra changes following long-term exposure to acidic substances, but the newer materials (Cention N and Activa) seemed to be more dimensionally stable and resistant to Ra changes than the older, well-known material (Vitremer). This may influence a clinician’s choice of restorative material for use in pediatric dentistry.

The following thesis is a comparison study which was performed in cooperation with Sika Sverige AB. The project was to examine concrete’s behaviour while being subjected to different accelerators which is used to speed up the hardening process in young concrete. Sika provided the materials and the instructions for the tests that were made. The tests used where almost like the tests being performed at Sika’s laboratories but with some adjustments to the testing equipment. According to the results of the tests a clear difference between the different accelerators were found. The conclusion that the efficiency of the different accelerators were affected on several variables such as cement type, hardening age and hardening temperature were drawn. Because of the corona outbreak (2020) the tests could not be performed in Sikas laboratories. The tests were therefore carried out at a temporary laboratory without any direct supervision and some professional equipment could not be obtained which resulted in replacements with creative solutions. These changes affected the individual test results with high certainty but should not interfere with the conclusions on account that all test samples were subjected to the same circumstances.

Cement production is responsible for around 7% of the global anthropogenic carbon dioxide emissions. More than half of these emissions are due to the unavoidable release of carbon dioxide upon thermal decomposition of the main raw material limestone. Many different options for carbon capture are currently being investigated to lower emissions, and one potential route to facilitate carbon capture could be the implementation of an electrified separate calcination step. However, potential effects on the phase composition of cement clinker need to be investigated, which is the aim of the present study. Phases of special interest are alite, belite, aluminate, ferrite, calcite, and lime.  The phase composition during clinker formation was examined through HT-XRD lab-scale experiments, allowing the phase transformations to be observed in situ. Two different methods of separate calcination were investigated, one method in which the raw meal was calcined separately, and one method where the limestone was calcined separately. The former yielded an alite amount similar to that of the reference experiments, whereas the latter method yielded a lower amount. It could, unfortunately, not be excluded that the difference was due to poor experimental conditions, and additional experiments are needed to investigate the matter further. The study does, however, indicate that a calcined raw meal might be used to produce a clinker of similar phase composition concerning major phases belite, aluminate, ferrite, alite, and free lime. A raw meal containing calcined limestone might, however, need longer residence time at clinkering temperature too obtain similar phase composition. In addition, a raw meal containing calcined limestone was observed to be carbonated to a greater extent upon reheating than a calcined raw meal. Further experiments are needed to fully understand the effects on clinker composition of an electrified separate calcination step, and several improvements to the experimental method are given in the study.

The modulus of elasticity is one of the basic characteristics of concrete defining elastic deformation of concrete and it plays a significant role in the static design of structures. Due to current trends in concrete technology, offering a wide variability in the proposals of the composition of concrete, there are changes not only in strength characteristics but also in the modulus of elasticity of concrete. The aim of this doctoral thesis is to study the dependence of different compositions on modulus of elasticity of concrete. Design of concrete composition is prepared with respect to the use of different types of cement, mineral admixtures, types and fractions of aggregates. The work is mainly focused on the determination of static modulus of elasticity in compression with the addition of dynamic modules. In the first phase determined modulus of elasticity are compared with tabulated values according to Eurocode 2, which are derived for the specific strength class of concrete. Part of this work is the compilation of the main technological aspects of concrete which can favorably affect the modulus of elasticity.