Desenvolvimento de aparato automatizado de slump test: ferramenta de controle de qualidade e de caracterização reológica de materiais
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Data
2018-07-31
Autores
Pereira, João Batista
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O ensaio de abatimento de tronco de cone, desenvolvido inicialmente como ferramenta de controle de qualidade para avaliar a consistência de materiais cimentícios e com grande aplicação no setor da construção civil, tem sido cada vez mais empregado para análise de materiais de diferentes setores, seja da indústria do petróleo, da mineração e mesmo de alimentos. O interesse de diferentes setores industriais pela medida do abatimento deve-se a esta possibilitar uma ferramenta de controle de qualidade de materiais e ainda fornecer um mecanismo simples e fácil para a determinação de um importante parâmetro reológico, a tensão limite de escoamento. Nesse contexto, esta dissertação de mestrado apresenta o desenvolvimento de um aparato experimental capaz de realizar, de forma automatizada, o ensaio de abatimento de tronco de cone (comumente conhecido por slump test), desde o levantamento do cone de Abrams até a medição do abatimento. A partir do equipamento desenvolvido, três abordagens são realizadas e discutidas ao longo desta dissertação, tendo como materiais avaliados os géis de carbopol (fluido teste reologicamente representativo de lamas), lamas, argamassas e concretos. A primeira abordagem diz respeito a funcionalidade e operacionalidade do aparato automatizado de slump test. A segunda abordagem apresenta modelos empíricos de determinação da tensão limite de escoamento e viscosidade aparente, a partir da medida mais rigorosa de abatimento e outras informações fornecidas pelo aparato automatizado. Por fim, a terceira abordagem apresenta a simulação numérica e a validação do slump test por meio do software FLUENT, considerando a propriedade não-Newtoniana (fluido de Herschel-Bulkley) dos materiais ensaiados, e a tentativa de validação de tal modelo. De forma geral, o aparato automatizado desenvolvido mostrou-se capaz de realizar o slump test, fornecendo medidas com maior rigor e menor influência do operador no ensaio; as medidas obtidas a partir do equipamento permitiram caracterizar, reologicamente, os materiais avaliados; e o modelo numérico desenvolvido, ainda com implementações a serem realizadas, apresentou-se capaz de fornecer a medida de abatimento.
The slump test was, initially, developed as a quality control tool for evaluating the consistency of cement-based materials, with many applications in civil engineering, it has been used for the analysis of materials in different sections of petrol industries, mining, and even food industries. The interest of these different industrial sections in the slump is due to its possible role as quality control tool of materials, providing an easy and simple mechanism for the determination of an important rheological parameter: the yield stress. In this context, this dissertation presents the development of an experimental apparatus capable of obtaining, in such automated way, the slump test, since the lifting of the Abrams cone to the obtaining of the slump. From the apparatus, three approaches are presented and discussed in this text, showing the results for the evaluation of materials such as carbopol gel (a rheological representative fluid of mud), mud, concrete and mortar. The first approach deals with the functionality of the automated apparatus for slump test. The second approach presents empiric models for the determination of yield stress and apparent viscosity, from the slump and further information obtained by the automated apparatus. The third and last approach presents the numerical simulation and validation of the slump test by the use of FLUENT software, considering the Non-Newtonian property (Herschel-Bulkley’s fluid) of the tested materials, and the trial of the model’s validation. In general, the automated apparatus has shown capable of realizing the slump test, providing measures more robust and less influenced by the operator; the obtained measures by the apparatus have permitted the rheological characterization of the evaluated materials; and the developed numerical model, though with some implementation to be made, has presented itself capable of providing the measure of the slump.
The slump test was, initially, developed as a quality control tool for evaluating the consistency of cement-based materials, with many applications in civil engineering, it has been used for the analysis of materials in different sections of petrol industries, mining, and even food industries. The interest of these different industrial sections in the slump is due to its possible role as quality control tool of materials, providing an easy and simple mechanism for the determination of an important rheological parameter: the yield stress. In this context, this dissertation presents the development of an experimental apparatus capable of obtaining, in such automated way, the slump test, since the lifting of the Abrams cone to the obtaining of the slump. From the apparatus, three approaches are presented and discussed in this text, showing the results for the evaluation of materials such as carbopol gel (a rheological representative fluid of mud), mud, concrete and mortar. The first approach deals with the functionality of the automated apparatus for slump test. The second approach presents empiric models for the determination of yield stress and apparent viscosity, from the slump and further information obtained by the automated apparatus. The third and last approach presents the numerical simulation and validation of the slump test by the use of FLUENT software, considering the Non-Newtonian property (Herschel-Bulkley’s fluid) of the tested materials, and the trial of the model’s validation. In general, the automated apparatus has shown capable of realizing the slump test, providing measures more robust and less influenced by the operator; the obtained measures by the apparatus have permitted the rheological characterization of the evaluated materials; and the developed numerical model, though with some implementation to be made, has presented itself capable of providing the measure of the slump.
Descrição
Palavras-chave
Slump test, Aparato automatizado, Reologia, Tensão limite de escoamento, Viscosidade aparente, Automated apparatus, Rheology, Yield stress, Apparent viscosity