Mestrado em Geotecnia, Estruturas e Construção Civil (EECA)
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Navegando Mestrado em Geotecnia, Estruturas e Construção Civil (EECA) por Por Orientador "Cascudo, Helena Carasek"
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Item Avaliação da deterioração das estruturas de concreto de estações de tratamento de esgoto(Universidade Federal de Goiás, 2018-07-23) Dias, Nayara Gracyelle; Matos, Oswaldo Cascudo; http://lattes.cnpq.br/3336749062812376; Cascudo, Helena Carasek; http://lattes.cnpq.br/3023241186996790; Cascudo, Helena Carasek; Matos, Oswaldo Cascudo; Cabral, Antonio Eduardo Bezerra; Campus, Marcus André SiqueiraThe environment of Wastewater Treatment Plants (WTP) is classified as one of the most aggressive for concrete. Plants with just a few years of operation may present deterioration in advanced levels, not only caused by the environment aggressivity, but also by the incorrect concrete specification with noncompliance of normative prerogatives and inadequate quality control during construction. The objective of this study is to contribute to the assessment of the degradation level of WTP’s reinforced concrete structures, including the origin and causes of such deterioration. In this context, the methodology applied involved the accomplishment of a literature review, an experimental research and a case study. The experimental research included diagnostic aspects and the concrete’s and sewer’s characterization. The case study was based on the GDE/UnB methodology adapted to WTP which consists in the assessment of the level of deterioration of concrete structures in order to reduce subjectivities. A WTP in the State of Goias with Chemically Assisted Primary treatment was studied. The WTP’ operational aspects showed they may influence in the deterioration of structures as well as the sewer’s characteristics and project specifications. The diagnostic tests measurement of carbonation thickness, silver nitrate spray for chloride evaluation, sclerometry, pacometry, electrical resistivity and sample extraction for evaluation in scanning electron microscope, in the concrete were important to guide the application of the methodology, although the results of electrical resistivity were not conclusive. The WTP presented characteristic manifestations according to the treatment process, such as the erosion of the channel that conduct to the desander, corrosion and disaggregation in the suction well and in the sludge storage tank. In a general way, the WTP presented GDE equal to 94 and therefore was classified with a high level of deterioration, making its maintenance necessary within the period of one year. This maintenance may be performed through the prioritization of units with their respective GDE individuals, considering the first unit to be treated, according to the research, must be the Tank of Transition.Item Estudo do precondicionamento para o ensaio de carbonatação acelerada do concreto(Universidade Federal de Goiás, 2019-12-18) Jungblut, Mônica Engel; Cascudo, Oswaldo; http://lattes.cnpq.br/3336749062812376; Cascudo, Helena Carasek; http://lattes.cnpq.br/3023241186996790; Cacudo, Helena Carasek; Possan, Edna; Oliveira, Andrielli Morais deDurability indicators are indispensable parameters for assessing and predicting the durability of the element and structure as a whole and must be easily quantifiable by laboratory testing. However, in Brazil there is not yet a standard to standardize the accelerated carbonation test and, therefore, the tests are performed based on international standards or literature data. The accelerated carbonation test is used to obtain the durability indicator for carbonation. One of the important steps for the accelerated carbonation test is preconditioning, which must occur after curing and prior to the onset of accelerated carbonation and aims to achieve an appropriate degree of saturation of the specimen so that the carbonation reactions can occur accelerated form. Due to the lack of standardization and the variety of methodologies found in the literature to perform this step, it was proposed to study the influence of different preconditioning methods on the carbonation results with a view to proposing a methodology. For this, four types of concrete were molded: three of them being without mineral addition, with water/binder of 0,40; 0,55 and 0,70; and onde concrete with replacement of 10% by weight of cement with metakaolin with 0,55 water/binder. The concretes were preconditioned by four different methods, following the recommendations of the ISO 1920-12 (2015), NF EN 13295 (2004), XP P 18-458 (2008) e RILEM TC 116-PDC (1999). Subsequently, the accelerated carbonation test was performed with 3% of CO2, 22°C and 65% of relative humidity. The results showed that the preconditioning type had a significant influence on the carbonation depths, and for the methods of ISO 1920-12 (2015) and NF EN 13295 (2004) the measured depths were smaller, while for the methods according to XP P 18-458 (2008) and RILEM TC 116- PDC (1999) were higher, considering the same type of concrete. In addition, it was observed that concretes with lower carbonation depths presented higher surface humidity at the beginning of the test, and this humidity was reduced at the end of the test, indicating that, for these concretes, the balance between internal humidity and ambient humidity had not yet been established during preconditioning ; this had a significant influence on the carbonation depth results. Thus, the simplest preconditioning method with the least influence of internal humidity in the accelerated carbonation test was XP P 18-458 (2008).