Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 117-121). Also available via the Internet.

Thesis (Master)--İzmir Institute of Technology, İzmir, 2004 / Includes bibliographical references (leaves. 43).

Thesis (Ph.D.). / Written for the Dept. of Civil Engineering and Applied Mechanics. Title from title page of PDF (viewed 2009/06/10). Includes bibliographical references.

Thesis (MEngSc)--University of Melbourne, Dept. of Chemical and Biomolecular Engineering, 2010. / Typescript. Includes bibliographical references (p. 105-110)

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Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Civil Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology / Self-compacting concrete (SCC) is a flowable self-consolidating concrete which can fill formwork without any external vibration. A self-compacting concrete mix requires the addition of superplasticiser (SP), which allows it to become more workable without the addition of excessive water to the mixture. The effect of different CEM I 52.5N cements produced by one company at different factories on self-compacting concrete was investigated. The properties of SCC are highly sensitive to changes in material properties, water content and addition of admixtures. For self-compacting concrete to be more accepted in South Africa, the effect that locally sourced materials have on SCC, partially replaced with extenders, needs to be investigated. The European guidelines for SCC (2005) determined the standard, through an extensive study, for the design and testing of self-compacting concrete. Using these guidelines, the properties of self-compacting concrete with the usage of local materials were investigated. The effect on SCC mixes was studied by using four cements; two types of SPs – partially replaced with two types of fly ash; and one type of slag. Mix design and tests were done according to the European Specification and Guidelines for Self-Compacting Concrete (2005). Using locally sourced materials (different cements, sand, coarse aggregate, fly ashes and slag), mixes were optimised with different SPs. Optimisation was achieved when self-compacting criteria, as found in the European guidelines, were adhered to, and the binders in these required mixes were then partially replaced with fly ash and slag at different concentrations. Tests done were the slump flow, V-funnel, L-box, sieve segregation resistance as well as the compressive strength tests. The results obtained were then compared with the properties prescribed by the European guidelines. The cements reacted differently when adding the SPs, and partially replacing fly ash and slag. According to the tests, replacing cement with extenders – in order to get a sufficient SCC – seemed to depend on the chemical and physical properties of each cement type, including the soluble alkali in the mixture, C3A, C3S and the surface area. The range, in which the concentration of these chemical and physical cement compounds should vary – in order to produce an acceptable SCC partially replaced by extenders – was determined and suggested to the cement producer. The main conclusion of this project is that cement properties vary sufficiently from factory to factory so as to influence the performance of an SCC mix. The problem becomes even bigger when such cements are extended with fly ash or slag, and when different SPs are used. When designing a stable SCC mix, these factors should be taken into account.

O objetivo do estudo foi avaliar as propriedades físicas, químicas e biológicas de um cimento experimental à base de Portland contendo diferentes agentes radiopacificadores. Os cimentos foram divididos em 6 grupos: 1. MTA-Angelus branco (controle), 2. cimento Portland branco (CP), 3. CP com 20% de óxido de zircônio (OZ), 4. CP/50% OZ, 5. CP com 20% de tungstato de cálcio (TC) e 6. CP/50% TC. As proporções foram determinadas em peso (80 e 50% de CP para 20 e 50% de radiopacificadores, respectivamente). Os cimentos experimentais foram manipulados utilizando 0,3 mL de líquido composto por 80% de água destilada e 20% de propilenoglicol, em volume. A caracterização dos materiais foi realizada em microscopia eletrônica de varredura (MEV), no modo EDS e em difratômetro de raios-X (XRD). Para os testes de radiopacidade, escoamento, espessura de filme e solubilidade foram seguidas as especificações no 57 da ANSI/ADA (2000). Na determinação do tempo de presa, foi empregada a norma ASTM C266/2008. Na análise do pH e liberação de íons cálcio foram analisados os períodos de 3, 24, 72 e 168 horas. Para análise da descoloração dentária, foram realizadas análises em espectrofotômetro, estereomicroscopia e MEV. Para análise da resposta inflamatória, foi utilizado o teste de implantação em subcutâneo de ratos. A utilização do óxido de zircônio e do tungstato de cálcio em combinação com o cimento Portland resultou no desenvolvimento de cimentos que exibiram uma radiopacidade próxima (20% de radiopacificadores) ou acima (50%) do recomendado pela norma no 57 da ANSI/ADA; tempo de presa mais prolongado, espessura de filme menor e escoamento mais elevado em comparação com o MTA-Angelus; solubilidade adequada e comparável ao MTA-Angelus, elevado pH e liberação de íons cálcio superior ao MTA-Angelus nos períodos iniciais e similar aos 7 dias, ausência de descoloração dentária e resposta inflamatória semelhante ao MTA-Angelus. / The aim of the study was to evaluate the physical, chemical and biological properties of an experimental calcium silicate-based cement with different concentrations of the radiopacifiers zirconium oxide and calcium tungstate. The materials were divided in 6 groups: 1. White MTA (control), 2. White Portland cement (PC), 3. PC with 20% zirconium oxide (ZO), 4. PC/50% ZO, 5. PC with 20% calcium tungstate (CT) and 6. PC/50% CT. The proportions were determined by weight. The cements were manipulated using 0.3 mL of liquid composed of 80% distilled water and 20% propylene glycol. The control was manipulated according to manufacturers instructions. The characterization of the materials was performed using scanning electron microscopy (SEM) in EDS mode and X-ray diffractometrer (XRD). For radiopacity, flowability, film thickness and solubility test, the specifications no 57 of ADA (2000) was followed. To determine the setting time, ASTM C266/2008 specifications was followed. For pH and calcium ion release assessment, the periods of 3, 24, 72 and 168 hours were evaluated. The analysis of dental discolouration was performed using spectrophotometer, stereomicroscopy and SEM. To evaluate the inflammatory response, the test of subcutaneous implantation in rats was used. The use of zirconium oxide and calcium tungstate in association with Portland cement resulted in development of cements with radiopacity nearly (20% radiopacifiers) or above (50%) the recommended by ANSI/ADA specifications n a 57, more prolonged setting time, lower film thickness and higher flowability in comparison with MTAAngelus, an adequate and comparable solubility with MTA-Angelus, high pH and calcium ion release higher than MTA-Angelus in the initial periods and similar at 7 days, absence of dental discolouration and inflammatory response similar to that presented by MTA-Angelus.

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This research includes the potential for resistance and the expansion that the soil presents, this evaluation was carried out through CBR tests. The soil cement technique was used to improve the physical and mechanical characteristics; this process consists in mixing the material with Portland cement type I. That combination forms soil cement 10%, 15% y 20%, which present an increase of the CBR (max: 138.7% and min: 91.9%) achieving a type of extraordinary subgrade to resist the structure of the pavement and a reduction of 7.18% in the expansion of the samples.

The deterioration of the surfaces of the constructions made with mortar C/A 1: 5 of Portland cement, are produced by being exposed to the emission of toxic gases emanating from the growing automobile fleet, this problem causes alternatives to be sought in order to counteract its effect on buildings and the environment. A new method to deal this problem is the incorporation of the titanium dioxide photocatalyst (TiO2) into the Portland cement mortar, which can develop self-cleaning and air purification properties to be in contact with sunlight. This work seeks to introduce this organic component to the Portland cement mortar, used for the facade charging and structural elements, for this purpose, different percentages (5%, 7.5% and 10%) of titanium dioxide (TiO2) are added and the properties of the modified mortars making use of [1] compression tests, [2] fluidity tests, [3] absorption tests and [4] photocatalytic activity tests with which the self-cleaning capacity was verified. This study concludes that the best percentage of titanium dioxide addition is 5%, with which the Portland cement mortar is granted self-cleaning property without substantially damaging its mechanical properties.