Comportamento reológico de pastas de cimento com adição de sílica ativa, nanossílica e dispersante policarboxílico

Senff, L.; Hotza, Dachamir; Repette, Wellington Longuini

doi:10.1590/s1517-70762010000100003

Cited by 14 publications

(11 citation statements)

References 21 publications

(22 reference statements)

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“…Previous studies [48] noted that the increasing content of NS causes a significant decrease in the setting time, 61 and 37%, using concentrations of 1 and 2% of Nano-silica. This behavior is related to the acceleration of the hydration reactions, provided by high specific surface.…”

Section: Effect Of Nsmentioning

confidence: 91%

Determination of time zero in high strength concrete containing superabsorbent polymer and nano-silica

et al. 2016

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The autogenous shrinkage is a phenomenon that occurs due to the appearance of tensile stresses in capillary pores. Inherent in the hydration process, not depending on external interference. In high strength concrete, autogenous shrinkage is most pronounced, due to the refinement of microstructure, the high cement content, presence of mineral addictions and low water/cement ratio, which interfere in the transport of water curing. In this context, Superabsorbent polymers (SAP) stand out for their ability to reduce or eliminate the autogenous shrinkage, because they absorb large amounts of water, which is subsequently released into the matrix, avoiding self-desiccation and the onset of tensile stresses (internal curing). However, studies show that SAP can reduce the mechanical strength, which can be compensated by addiction of Nano-silica (NS). In this paper, the effect of these additions in Time Zero (T 0 ) was evaluated. T 0 determines the time at which the material starts to behave as a solid, with the development of a rigid mineral skeleton to oppose the volumetric variations that occurs in the paste, which can lead to cracking, compromising esthetics, durability, and structures safety. The ultrasonic pulse velocity test performed the T 0 , which measures the velocity of propagation of an ultrasonic wave through the material and is taken as the time when a sudden change occurs at this velocity. Nine blends were made containing SAP and NS, where it was found that SAP addition increases the T 0 (up to 11%), while NS decrease its value (in 55%).

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Section: Effect Of Nsmentioning

confidence: 91%

Determination of time zero in high strength concrete containing superabsorbent polymer and nano-silica

et al. 2016

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“…Figura 1 -Ilustração esquemática de argamassas com comportamento de fluido de Bingham (CARDOSO, 2009;BANFILL, 2005) Através de uma abordagem simplificada, as argamassas frescas costumam ser consideradas fluidos de Bingham (BANFILL, 2006;SENFF et al, 2010;RIBEIRO, 2013), ou seja, materiais que apresentam uma tensão mínima para iniciar o escoamento (tensão de escoamento) e, em fluxo, têm uma relação linear entre tensão e taxa de cisalhamento ( A distância entre as partículas influencia significativamente o comportamento reológico das suspensões, apresentando uma relação direta com a fluidez (CARDOSO, 2009 …”

Section: -86unclassified

Influência Da Adição Do Resíduo De Corte De Mármore E Granito (Rcmg) Na Reologia Das Argamassas

Santos¹,

Apolinário²,

Ribeiro³

2013

ANAP

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RESUMO:A construção civil é a atividade que mais consome recursos não-renováveis em todo o planeta. Em contrapartida, possui a capacidade de incorporar rejeitos gerados por outras atividades, minimizando impactos oriundos de descartes inadequados e reduzindo o seu próprio consumo de matéria-prima. Nesse cenário está o resíduo de corte de mármore e granito (RCMG), o qual ainda não possui um destino adequado, sendo disposto indevidamente no meio ambiente, resultando em impactos ambientais que podem comprometer a flora e a fauna. Em matrizes cimentíceas, o RCMG tem a capacidade de agir como filler, ocupando os espaços vazios existentes em argamassas e concretos e, assim, modificando suas características reológicas. No presente estudo, foram adicionados teores de 5%, 10% e 15% de resíduo, em relação à massa de cimento, em argamassas de cimento Portland. Em seguida, avaliaram-se a densidade de massa, o teor de ar incorporado, a retenção de água, além de suas propriedades reológicas, por meio da mesa de consistência, flow table, e do squeeze flow. Os resultados indicaram que a argamassa confeccionada com adição do resíduo de 10% apresentou o melhor desempenho, concluindo-se, então, que a utilização do RCMG é uma alternativa tecnicamente viável para adição a argamassas.Palavras-chave: resíduo, mármore e granito, argamassas, reologia.

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“…Several studies on nanomaterials applied to cementitious materials can be found in the literature [5][6][7][8][9][10][11][12][13]. Overall, the research focused in the addition of nano-silica or carbon nanotubes to Portland cements, mortars and concretes.…”

Section: Introductionmentioning

confidence: 99%

“…Senff et al [12] investigated the rheological behavior of cement pastes containing silica fume, nanosilica and polycarboxylate based chemical admixture. The used nano-silica was in the form of a suspension.…”

Section: Introductionmentioning

confidence: 99%

Mechanical properties and microstructure of high performance concrete containing stabilized nano-silica

et al. 2017

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Nanotechnology can significantly improve the mechanical strength and durability of concrete. At the nanoscale, good dispersion of constituent materials is an essential factor for the improvement of concrete properties. In this scenario, the objective of this research was to evaluate the mechanical properties of high performance concrete containing stabilized nano-silica. The incorporation of nano-silica to the polycarboxylate chemical admixture allowed its application in concrete, since the nano-silica was evenly dispersed in the concrete mass. For this study, three different concretes were employed: a reference concrete, one containing stabilized nano-silica and another containing a mixture of silica fume and stabilized nanosilica. The evaluated concrete mechanical properties were the axial compressive strength and secant modulus of elasticity measured in three different ages. The results indicated a substantial increase in concrete compressive strength and modulus of elasticity with the addition of stabilized nano-silica combined with a reduction in cement content. The results also showed that use of stabilized nano-silica proved to be very advantageous, especially when mixed with silica fume. When they were combined, a synergy effect occurred in the concrete that was of chemical nature in addition to the physical effect of better concrete particle packaging. Analysis by scanning electron microscopy showed the improvement in microstructure of concretes with stabilized nano-silica, which contributed to gains in mechanical properties.

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Comportamento reológico de pastas de cimento com adição de sílica ativa, nanossílica e dispersante policarboxílico

Cited by 14 publications

References 21 publications

Determination of time zero in high strength concrete containing superabsorbent polymer and nano-silica

Determination of time zero in high strength concrete containing superabsorbent polymer and nano-silica

Influência Da Adição Do Resíduo De Corte De Mármore E Granito (Rcmg) Na Reologia Das Argamassas

Mechanical properties and microstructure of high performance concrete containing stabilized nano-silica

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