Pozzolanic activity of calcined halloysite-rich kaolinitic clays

Tironi, Alejandra; Cravero, Fiorella; Scian, Alberto N.; Irassar, Edgardo F.

doi:10.1016/j.clay.2017.07.018

Cited by 54 publications

(29 citation statements)

References 30 publications

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“…A peak of 917 cm −1 is The FTIR spectra further describes the changes in the chemical environment of nanocomposite in Figure 3. Before sintering, the characteristic peaks of 3695 cm −1 , 3618 cm −1 and 3445 cm −1 reflect the stretching vibration of -OH: 3695 cm −1 corresponds to the -OH vibration in the kaolinite interlayer, 3618 cm −1 corresponds to the -OH vibration between the kaolinite silicon layer and the aluminum layer, and 3445 cm −1 corresponds to the vibration of -OH in the absorbed water in the sample [4,30,31]. Besides, the characteristic peak 1626 cm −1 represents the bending vibration of -OH in absorbed water and the vibration of aromatic C=C in GO [29,31].…”

Section: Resultsmentioning

confidence: 99%

Self-Heating Graphene Nanocomposite Bricks: A Case Study in China

Tang

Gong

et al. 2020

Materials

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In cold climate regions, the energy associated with indoor heating constitutes a large portion of energy consumption. Increasing energy utilization efficiency is critically important for both economic and environmental reasons. Directly converting electrical energy to thermal energy using joule heating construction elements can save energy and investment to the water pipelines which have been extensively used for indoor heating in China. The fired brick has been extensively used to make pavements, walls and other masonry. Taking advantage of the high dispersion quality of graphene oxide (GO) in water, as well as the firing process used to make fired bricks, graphene nanocomposite bricks with excellent electrical properties and improved mechanical performance were prepared in China. The compressive strength of the bricks showed a substantial increase from 3.15 MPa to 7.21 MPa when GO concentration was 0.1 wt.%. Through applying 5 volts of electrical field within 5 minutes, the nanocomposites can be heated from room temperature to 60 °C, 110 °C and 160 °C for the nanocomposite bricks with graphene concentration of 3 wt.%, 4 wt.% and 5 wt.%, respectively, due to the extremely low percolation threshold (~0.5 wt.%) and high conductivity (10 Ω·cm at 1 wt.%). The sheets were connected more tightly when the GO content was increased. The thermal efficiency can reach up to 88% based on the applied voltage, measured resistance and temperature rise curves.

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Section: Resultsmentioning

confidence: 99%

Self-Heating Graphene Nanocomposite Bricks: A Case Study in China

Tang

Gong

et al. 2020

Materials

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“…and 950°C was led by the filler effect [12,13]. All samples with OPC substitution degrees from 5 wt.% up to 20 wt.% fulfilled the minimal SAI requirements according to [61] for all investigated curing ages.…”

Section: Microstructural Characterisation Of the Cured Bindersmentioning

confidence: 91%

“…2.3.2 Compressive strength test, relative strength test and pozzolanicity of the hardened bindersFor each mixture, the compressive strength was measured on three specimens with same curing ages using a compression test plant (TONICOMP III, Toni Technik GmbH, Germany), conform to the standard DIN EN 196-1[48], with additional displacement transducers. An indirect evaluation method of the pozzolanic activity, namely the strength activity index (SAI), is applied to measure physical properties of hardened test samples and to evaluate the magnitude of the pozzolanic activity[16,[52][53][54][55][56][57][58][59][60][61].…”

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confidence: 99%

Gravel wash mud, a quarry waste material as supplementary cementitious material (SCM)

Thapa

Waldmann

Simon

2019

Cement and Concrete Research

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The suitability of gravel wash mud (GWM), a sludge waste from gravel quarrying, is examined for its use as a partial Ordinary Portland cement (OPC) clinker substitute. The gravel wash mud was dried, milled into a fine powder and calcined at 750°C, 850°C and 950°C. In this study, various characterisation methods including particle size distribution (PSD), X-ray fluorescence (XRF), X-ray diffraction (XRD) and the simultaneous thermal analysis (STA) were applied on the calcined GWM powders to determine the optimal calcination temperature. Over 200 specimens were prepared based on different cement paste and mortar mixes to investigate the potential of calcined GWM powders as SCMs. The pozzolanic activity of the GWM powders was verified by applying strength-based evaluation methods, simultaneous thermal analysis and SEM on hardened samples. Very promising strengthenhancing capacities were observed for samples containing GWM powders calcined at 850°C with a OPC replacement level of 20 wt.%.

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“…A determinação da atividade pozolônica de materiais pode ser realizada por diferentes métodos, seja a partir de análise química, fisíco-química, minerológica ou de propriedades mecânicas, a partir de testes com corpos de prova, em que há a substituição de parcelas do composto em estudo pelo cimento. As análises químicas normalmente são baseadas na avaliação da reação de pozolanas com hidróxido de cálcio ou resultante da hidratação do cimento, como é o caso do método Chapelle [18,28,29], método Frattini [30][31][32], entre outros [22]. Métodos físico-químicos e mineralógicos também podem ser utilizados, e abrangem a difratometria de raios X (DRX) [33], que possibilita a identificação de fases cristalinas das amostras; termogravimetria e análise térmica diferencial (TG/DSC) [26,33], microscopia eletrônica de varredura (MEV) [33], permitindo uma avaliação morfológica das amostras submetidas às reações de verificação de pozolanicidade; medição de condutividade associado aos testes de reação de pozolanas [31,32] e determinação da área superficial específica, que permite inferir a intensidade de ocorrência das reações.…”

Section: Substituição Ou Adição Ao Cimentounclassified

“…Maiores áreas específicas proporcionam reações mais eficazes. Como método mecânico, pode-se citar o índice de resistência à compressão (IRC) [31][32][33].…”

Section: Substituição Ou Adição Ao Cimentounclassified

Aplicação de resíduos na fabricação de concreto: como técnicas analíticas de caracterização podem auxiliar na escolha preliminar do material mais adequado?

Bragagnolo

Korf

2020

Matéria (Rio J.)

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RESUMO A preocupação frente aos impactos negativos resultantes da obtenção e produção de agregados naturais e do cimento na produção do concreto, bem como a possibilidade de escassez desses, acabaram alavancando a busca por materiais alternativos. Dentre esses materiais, diversos estudos já avaliaram a aplicação de subprodutos de diferentes setores industriais para a fabricação do concreto. Contudo, considerando a gama de resíduos existentes, sem ainda possuir algum valor agregado, torna-se interessante avaliá-los para essa finalidade. Para tanto, a avaliação do potencial desses materiais exige a aplicação de diferentes técnicas para análise de diversas propriedades que são desejáveis ou requeridas. Nesse sentido, essa revisão bibliográfica buscou reunir as principais técnicas e metodologias que são aplicadas para a identificação das principais características que possibilitem sua aplicação como substitutos parciais de agregados ou cimento, em misturas para a fabricação do concreto.

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Pozzolanic activity of calcined halloysite-rich kaolinitic clays

Cited by 54 publications

References 30 publications

Self-Heating Graphene Nanocomposite Bricks: A Case Study in China

Self-Heating Graphene Nanocomposite Bricks: A Case Study in China

Gravel wash mud, a quarry waste material as supplementary cementitious material (SCM)

Aplicação de resíduos na fabricação de concreto: como técnicas analíticas de caracterização podem auxiliar na escolha preliminar do material mais adequado?

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