Characterization of alkali activated kaolinitic clay

Slaty, Faten; Khoury, Hani; Wastiels, Jan; Rahier, Hubert

doi:10.1016/j.clay.2013.02.005

Cited by 91 publications

(31 citation statements)

References 21 publications

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“…The presence of carbonates in the samples was confirmed also by FTIR spectra. It was suspected that the presence of carbonate may be related to uptake of atmospheric CO 2 and its reaction with NaOH in accordance with earlier reports by Slaty et al (2013) and Aldabsheh et al (2015).…”

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confidence: 87%

The influence of alkali concentration and temperature on chemical activation of halloysite [abstract].

Maziarz¹,

Matusik²

2016

geol

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CC-BY 4.0 License requiring that the original work has been properly cited.The suspensions consisting of 2 g of halloysite and 50 mL of appropriate solution were mixed for 24 h using magnetic stirrer. Subsequently, the samples were washed with water and dried at 60°C. The prepared materials were characterized using XRD and FTIR methods.The IR results revealed that the concentrations of NaOH below 5 mol/L at room temperature did not cause significant changes in spectra of the tested samples. However, the results of experiments carried out in the temperature range from 60°C to 90°C showed that the temperature of the suspension can significantly affect the alkali activation. Based on the IR spectra the reaction at 50°C did not alter the structure of halloysite, in contrast to 60°C, 70°C, 80°C and 90°C temperatures. The changes of relative intensities of the bands associated with inner surface hydroxyls were observed in the 3700-3600 cm −1 region. These results suggest a gradual removal of inner surface hydroxyls, with the temperature increase. The results also indicated a gradual increase of intensity and broadening of the band with the maximum at 3430 cm −1 and 1647 cm −1 which were attributed to H-O-H stretching and bending vibrations of adsorbed water, respectively. It can be also observed that base treatment at higher temperature also caused structural changes within the aluminosilicate framework of halloysite. The frequency shift and broadening of bands assigned to Si-O-Si stretching (1033 cm −1 , 1008 cm −1 ) and bending (540 cm −1 ) vibrations were observed. The perturbations and/or removal of Al-O-H was confirmed by the decrease of bands intensity assigned to The influence of alkali activation on clay minerals is not thoroughly investigated, particularly in terms of its impact on adsorption possibilities of clay minerals. One of the studied applications of base treated clay minerals was to control sustained drug release (Wang et al. 2013). Based on the recent studies, the base treatment can cause changes in structure, texture, and morphology of clay minerals. These changes are related to partial dissolution of layered structure and subsequent release of Si and Al to the solution (White et al. 2012, Yuan et al. 2015. This modification can be especially promising in case of halloysite, which is a clay mineral revealing unique nanoscale tubular morphology. Previous studies indicate that selective dissolution of halloysite's aluminosilicate layers can lead to opening of the tubes interior (lumen) (Wang et al. 2013). This type of structural alteration can influence utilization possibilities of halloysite. Therefore, the aim of this work is to investigate the influence of alkali concentration and reaction temperature on the halloysite structure.The halloysite used in the studies came from Polish deposit located in Dunino, near Legnica (SW Poland) which is constantly exploited. The base activation was carried out using sodium hydroxide (NaOH). Firstly, the effect of NaOH concentration on activation efficiency was ...

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supporting

confidence: 87%

The influence of alkali concentration and temperature on chemical activation of halloysite [abstract].

Maziarz¹,

Matusik²

2016

geol

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“…Among the binder-development study alternatives to cement, geopolymer binders have turned out to be the most promising [5]. Geopolymers can be produced using natural or industrial wastes like fly ash, blast furnace slag, metakaolin (or red mud) [6].…”

Section: Introduction mentioning

confidence: 99%

Behaviour of Geopolymer Mortars after Exposure to Elevated Temperatures

Kaya

Uysal²,

Yılmaz

et al. 2018

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In this study it was investigated the behavior of class F fly ash based geopolymer mortars subjected to elevated temperatures. Geopolimer composites were prepared with CEN-sand, water, fly ash as the binder, nSiO2Na2O and NaOH mixture combination as alkali activator. After mixing fresh geopolymer mixture, prismatic specimens were prepared using 40 mm × 40 mm × 160 mm prism molds. After molding, fresh geopolymer mortar samples with their mold were subjected to heat curing at 50 °C, 60 °C, 70 °C, 80 °C, 90 °C and 100 °C temperature for 48 hours in an oven. After 48 hours initial heat curing, the hardened samples were taken out of their mold. Then, they were further cured by leaving them in laboratory environment at about 22 ± 2 °C temperature, until 28 days together with heat curing duration. At the end of 28 days, geopolymer mortar samples developed flexural strength values between 2,9 MPa and 8,51 MPa. Geopolymer mortar samples developed compressive strength values between 7,63 MPa and 50,64 MPa. High temperature experiments were conducted to observe behaviour of geopolymer mortars at elevated temperatures. The control cement mortar mixtures were also prepared and subjected to high temperature exposure in comparison to geopolymer mortar mixtures. Control cement mortars were cured at laboratory environment for 28 days without initial temperature curing. Control cement mortar mixtures and geopolymer mortar mixtures were exposed to elevated temperatures of 200 °C, 400 °C, 600 °C and 800 °C temperature. The unit weight, ultrasonic pulse velocity, flexural and compressive strength of all mixtures were measured before and after high temperature exposure. Scanning electron microscope (SEM) images of the mixtures were taken and X-ray fluorescence (XRF) spectrometer analyses were carried out. It was observed that there was an increase in the flexural and compressive strengths of some geopolymer mortars after high temperature exposure. In general, geopolymer mortars exhibited better performance at elevated temperatures in comparison to control cement mortar mixture.

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“…The strength of alkali-activated material correlates with NaOH content. At lower alkali activation, geopolymers have a compressive strength of 13 MPa [76]. The required strength of a brick for a wall is around 5 MPa.…”

Section: Resultsmentioning

confidence: 99%

Alkali-activated binder containing wastes: a study with rice husk ash and red ceramic

et al. 2017

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In addition to several positive aspects in technical properties, geopolymeric binders have considerable advantages in the environmental point of view, with lower energy consumption and lower CO 2 emission. In this study, it was conducted an overview about the utilized materials by some Brazilian researchers in geopolymers production, and also an experiment employing two types of wastes (red ceramic waste and rice husk ash). The compressive strength of the resulting material developed very fast, reaching a value of 11 MPa after one day. The microstructure was evaluated by scanning electron microscopy, revealing a compact microstructure and the presence of starting materials from the red ceramic waste that not completely reacted. The results indicated the feasibility of producing geopolymeric material without using commercial sodium silicate and cured at room temperature, showing an option for building materials production with lower environmental impacts. Keywords: geopolymer, alternative materials, sustainability, building materials. Resumo Além de vários aspectos positivos nas propriedades técnicas, aglomerantes geopoliméricos têm consideráveis vantagens do ponto de vista ambiental, com menor consumo de energia e menor emissão de CO 2 . Neste estudo, conduziu-se uma revisão sobre os materiais empregados na produção de geopolímeros por alguns pesquisadores brasileiros, e também um experimento empregando-se dois tipos de resíduos (resíduos de cerâmica vermelha e cinza de casca de arroz). A resistência à compressão do material resul-

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Characterization of alkali activated kaolinitic clay

Cited by 91 publications

References 21 publications

The influence of alkali concentration and temperature on chemical activation of halloysite [abstract].

The influence of alkali concentration and temperature on chemical activation of halloysite [abstract].

Behaviour of Geopolymer Mortars after Exposure to Elevated Temperatures

Alkali-activated binder containing wastes: a study with rice husk ash and red ceramic

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