Papers by Nicole Hasparyk
Journal of Materials in Civil Engineering
SP-229: Quality of Concrete Structures and Recent Advances in Concrete Materials and Testing, 2005
IOP conference series, Nov 1, 2022
CONGRESO LATINO-AMERICANO DE PATOLOGÍA DE CONSTRUCCIÓN, 2021
Delayed ettringite formation (DEF) is a pathological phenomenon responsible for several types of ... more Delayed ettringite formation (DEF) is a pathological phenomenon responsible for several types of damage to concrete elements and structures. The lack of test methods, protocols and preventive standards based on concrete mixes and inhibitor admixtures are concerned. This paper presents the results from an experimental program performed in the laboratory with a procedure developed for inducing DEF. An initial thermal cycle was conducted accompanied by the exposition of mortars to a specific environment in order to monitor expansions over time. Mortars were cast with silica fume as partial cement replacement at ratios of 0%, 4%, 8% and 12%, by volume. The adopted procedure was able of promoting DEF and the silica fume presented potential to mitigate DEF expansions, even though some ettringite crystals was produced in the cement matrix by microstructural analyses at six months.
Congresso Brasileiro de Patologia das Construções
Entre as reações expansivas deletérias que afetam o desempenho e a durabilidade de estruturas de ... more Entre as reações expansivas deletérias que afetam o desempenho e a durabilidade de estruturas de concreto, se encontram aquelas que envolvem os íons sulfatos. Quando esses íons provém de fontes internas, ainda existem lacunas sobre as medidas preventivas mais apropriadas relacionadas aos materiais constituintes do concreto, a não ser que o mesmo seja refrigerado quando do seu lançamento e aplicação. Diante do exposto, este trabalho apresenta resultados de uma pesquisaem laboratório para avaliar a interveniência da adição de sílica ativa em concretos frente à DEF (Delayed Ettringite Formation-Formação tardia de etringita). Desta forma, os protocolos para a indução da DEF nos concretos estudados seguiram as recomendações de método desenvolvido no Brasil. Assim, ensaios para avaliação da expansão, de propriedades mecânicas e análise microestrutural foram realizados com o objetivo de avaliar o potencial desta adição mineral em mitigar expansões e danos em decorrência da DEF.
CONGRESO LATINO-AMERICANO DE PATOLOGÍA DE CONSTRUCCIÓN, 2021
This paper aims to present the behavior of concrete containing rice husk-ash (RHA) that were unde... more This paper aims to present the behavior of concrete containing rice husk-ash (RHA) that were undergone a thermal curing. A particular test method was used to promote an initial thermal curing up to 85ºC to trigger DEF, followed by a specific exposure condition (at 38ºC). Expansion measurements and microstructural analyses were performed to evaluate the level of attack and the integrity of concretes with and without rice husk-ash (RHA). Mechanical properties were assessed in order to monitor damage evolution of generated expansions from DEF over time and up to six months. Concrete tests have indicated that the RHA tested was able to reduce DEF expansions, nonetheless, it was not enough to a complete mitigation and avoid DEF and damages.
PRO 40: International RILEM Conference on …, 2004
This paper presents an experimental program carried out with conventional concrete using rice hus... more This paper presents an experimental program carried out with conventional concrete using rice husk-ash (RHA) in partial substitution for cement. The RHA is a product obtained from the generation process of electric power in a thermoelectric Power Plant. The ash is produced in suspension, inside a furnace with controlled burning, resulting in a completely amorphous material. The experimental program comprised the physical, chemical and micro structural characterization of the pozzolan RHA, including ana lyses by the X-ray diffraction technique. The hydration heat of cement combined with RHA was also verified. Tests with mortar, aimed at studying the efficiency of pozzolan in reducing the alkali-aggregate reaction (AAR), and with concrete, in order to investigate its properties, were also performed in the presence of RHA. The RHA was used in two conditions-in natural and in ground states-and was employed in substitution for cement in 5 contents as follows: 8%, 10%, 12%, 16% and 20%. The main results indicate a high pozzolanic activity of the RHA studied, which proved effective in reducing the AAR expansion. In addition, the concrete properties evaluated with RHA incorporation proved satisfactory. The results of this study indicate that this RHA is an attractive pozzolanic admixture due to its high reactivity as well as its environmental benefits.
CONGRESO LATINO-AMERICANO DE PATOLOGÍA DE CONSTRUCCIÓN, 2021
Este trabalho apresenta o comportamento de concretos submetidos a dois diferentes métodos de ensa... more Este trabalho apresenta o comportamento de concretos submetidos a dois diferentes métodos de ensaio a fim de avaliar o potencial para a DEF (Métodos Francês e Brasileiro). Concretos foram moldados e submetidos a cura térmica até 85ºC, sendo a principal diferença entre os métodos o ambiente de exposição ao longo do tempo. Ensaios mecânicos e de expansão, além de análises microestruturais foram realizados a fim de verificar o nível de dano a partir das expansões de DEF atingidas. Os resultados obtidos indicaram comportamentos distintos entre os métodos testados. Para a idade de seis meses de ensaio, o método brasileiro se mostrou mais acurado para avaliar a DEF, considerando o cimento testado responsável por essa patologia em campo.
Journal of Building Engineering, 2022
Construction Technologies and Architecture, 2022
Bio-concretes are receiving special attention in recent research as an alternative for climate ch... more Bio-concretes are receiving special attention in recent research as an alternative for climate change mitigation due to their low carbon footprints. Different bio-based materials can be used, e.g., wood shavings, bamboo, rice husk, and coconut. However, various methodological parameters can influence the carbon footprint of bio-based materials, especially bio-concretes, like biogenic carbon, amount of carbon in dry matter, rotation period of bio-aggregates, and type of cementitious materials. It is important to have easier ways of estimating the carbon footprint of bio-concretes, using parameters and data easily available. This research aims to evaluate the (1) carbon footprint of different mixtures of three bio-concretes (wood bio-concrete - WBC, bamboo bio-concrete - BBC and rice husk bio-concrete - RBC), and the (2) development of GHG emissions curves for bio-concretes specification based on easily available data (such as density, biomass content, and compressive strength). Based...
Cement and Concrete Research, 2010
This work presents the results of an experimental research concerning the use of fibers in mortar... more This work presents the results of an experimental research concerning the use of fibers in mortar specimens subjected to alkali-aggregate reaction (AAR). Two types of steel fibers (0.16 mm diameter and 6.0 mm length, and 0.20 mm diameter and 13.0 mm length) were ...
ACI Materials Journal, 2021
Matéria (Rio de Janeiro)
RESUMO No Brasil várias estruturas de concreto tem se mostrado deterioradas precocemente em decor... more RESUMO No Brasil várias estruturas de concreto tem se mostrado deterioradas precocemente em decorrência da formação tardia da etringita (DEF). Ainda existem muitas lacunas e, em especial, no que diz respeito ao comportamento de materiais cimentícios suplementares e sua eficácia no combate das expansões por DEF. O acompanhamento e controle em obra muitas vezes trazem preocupação futura, pós lançamento dos concretos, haja vista as altas temperaturas atingidas pela geração de calor de hidratação. Diante do exposto, esta pesquisa traz dois estudos de caso brasileiros, nos quais as temperaturas ficaram próximas de 70°C, mesmo na presença de cimento pozolânico e incorporação de metacaulim. No sentido de avançar no entendimento deste processo na presença do metacaulim, e contribuir com o meio técnico, foi desenvolvido um estudo em laboratório em compósitos cimentícios sem e com a incorporação desta adição, em vários teores. Os dados dos concretos observados em campo mostraram que mesmo ten...
There are well-established preventive measures to reduce the potential damage to a concrete struc... more There are well-established preventive measures to reduce the potential damage to a concrete structure when reactive aggregates are used. However, there are only few efficient measures to apply to a structure once the deleterious reaction has already been established. So as to extend the ASR repair strategies, the present study aimed to verify, in laboratory, the mitigating potential of silane compositions in residual expansion of affected mortars cast with reactive aggregates. The results indicated that silane-based treatments, mainly the one containing octyltriethoxysilane, are very promising. Water absorption measurements and microstructural characterization bywith scanning electron microscopy of the mortar bars treated with silanes were also included in the experimental program.
Caderno especial dos melhores artigos do Congresso Brasileiro do Concreto, 2021
Estudo da Formação da Etringita Tardia (DEF) por meio do ensaio SDT (Stiffness Damage Test) The S... more Estudo da Formação da Etringita Tardia (DEF) por meio do ensaio SDT (Stiffness Damage Test) The Study of DEF by SDI (Stiffness Damage Test) Dioice Schovanz (1); Francieli Tiecher (2); Nicole P. Hasparyk (3); Selmo C. Kuperman (4)
CONCRETO & Construções, 2021
Neste estudo objetivou-se alertar a comunidade técnico-cientifica local com relação à investigaçã... more Neste estudo objetivou-se alertar a comunidade técnico-cientifica local com relação à investigação do grau de reatividade potencial, quanto à Reção Álcali-Agregado (RAA), de 11 areias extraídas no Estado do Paraná. Foram investigados os aspectos geológicos e ascaracterísticas físico-químicas dos agregados estudados. Com relação aos resultados, 73% das amostras apresentaram expansões superiores ao previsto pela norma NBR 15577-1:2018. Além disso, os teores de finos foram compreendidos fora da zona ótima indicada pela NBR 7211:2009, induzindo a dificuldades para o alcance de trabalhabilidades desejadas em concretos e argamassas. Os grãos apresentaram tipologias diferenciadas e diferentes fases minerais associadas. Quanto ao grau de expansibilidade, concluiu-se que os agregados da Formação Ponta Grossa não apresentaram reatividade potencial. Já os agregados com potencial reativo foram os dos depósitos aluvionares, com fontes em rochas migmatíticas e gnáissicas, em rochas areníticas e conglomeráticas (Grupo Itararé) e os de origem eólica (Formação Caiuá).
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Papers by Nicole Hasparyk