Intrinsic parameters involved in the synthesis of metakaolin based geopolymer: Microstructure analysis

Meftah, Mahdi; Oueslati, Walid; Chorfi, Nejmeddine; Amara, Abdesslem Ben Haj

doi:10.1016/j.jallcom.2016.07.297

Cited by 16 publications

(6 citation statements)

References 34 publications

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“…Fluorite (CaF 2 , PDS-00-035-0846) was used as an internal standard. The crystal structure information of the refined phases O-H stretching and bending modes of absorbed molecular water in the metakaolin structure 11,13,15 . The band in the wavenumber range 3500-3300 cm -1 is weaker for MK2 than that for MK1 and the signals located in the range 3700-3600 cm -1 are almost imperceptible, which confirms the lower kaolinite content of MK2 when compared to that of MK1 15 .…”

Section: Materials and Characterizationmentioning

confidence: 99%

“…As well as in the metakaolins analyses, this peak at 3434 cm -1 for G1 was more intense than for G2 due to the higher amount of kaolinite found by the Rietveld refinement in G1. Figure 6 presents other characteristic bands of geopolymers, described as follows: below 700 cm -1 , related to the asymmetric vibration of the Si-O-(Si, Al) bonds, around 1000 cm -1 , related to Si-O-Si bonds and around 1600 cm -1 , attributed to stretching vibrations (H-O) of absorbed or structural water molecules present in the geopolymer porosity [11][12][13] .…”

Section: Ftir Analysismentioning

confidence: 99%

“…The metakaolin (MK), obtained by the controlled burning of kaolin, has been one of the precursors most used to produce geopolymers, since with the transformation of kaolin into metakaolin the resulting material becomes a much more reactive pozzolan. Some authors have obtained interesting results producing geopolymers from metakaolin, with great potential to be applied as alternative materials to conventional concrete based Ordinary Portland Cement (OPC concrete) 8,[11][12][13] . This paper presents the results of a study carried out where the structure of two metakaolin samples and the geopolymer matrices obtained by their alkaline activation were evaluated by thermal, mechanical and microstructural analysis.…”

Section: Introductionmentioning

confidence: 99%

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Thermal, Mechanical and Microstructural Analysis of Metakaolin Based Geopolymers

et al. 2019

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In the present work, geopolymer matrices were developed by alkali activation of metakaolin, using NaOH and sodium silicate as activators. The samples of metakaolin and matrices were studied by thermal analysis (TGA/DTA) at temperatures between 22°C and 1000°C in a nitrogen atmosphere with a heating rate of 10°C/min. The analyses showed gradual mass losses for MK1 and MK2, occurring in the temperature range of 350-700°C, associated with the dehydroxylation of the kaolinite present in the metakaolin samples, when transforming into reactive metakaolin. Thermal analysis allowed to identify mass losses associated with the different events that occurred during the formation of the geopolymer structure. The formation of amorphous geopolymer networks was confirmed by the XRD and FTIR techniques. The quantitative analysis of XRD results by using the Rietveld method allowed determine the amorphous and crystalline content of the precursors and geopolymers. The results obtained, after analyzing the matrices, showed that the geopolymers obtained presented a mechanical performance comparable to systems found in the literature, with uniaxial compressive strengths ranging from 38-50 MPa and stiffness around 7 GPa. Hence, these systems are suitable for their future use as alternative binder materials for the production of mortars and concretes.

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Section: Materials and Characterizationmentioning

confidence: 99%

Section: Ftir Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermal, Mechanical and Microstructural Analysis of Metakaolin Based Geopolymers

et al. 2019

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“…In this environment, a three-dimensional network structure of geopolymers is formed due to the rapid dissolution and reunion reaction of silica-aluminum active substances. The geopolymer structure mainly contains three different sialate units [4], namely, poly sialate (-Si-O-Al-), poly sialate-siloxo (-Si-O-Al-O-Si-), and polysialate-disiloxo (-Si-O-Al-O-Si-O-Si-), shown in Figure 1. The properties of the final products are highly dependent on the cross-linking degree of the different silico-aluminate polymeric chains [5].…”

Section: Introductionmentioning

confidence: 99%

The Mechanical Performance and Reaction Mechanism of Slag-Based Organic–Inorganic Composite Geopolymers

Xing,

Xu,

Zhang

et al. 2024

Materials

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A series of organic–inorganic composite geopolymer paste samples were prepared with slag-based geopolymer and three types of hydrophilic organic polymers, i.e., PVA, PAA, and CPAM, by ordinary molding and pressure-mixing processes. The reaction mechanism between slag-based geopolymer and organic polymers was studied by FT-IR, NMR, and SEM techniques. The experimental results showed that the slag-based geopolymer with the addition of 3% PVA presented the highest 28-day flexural strength of 19.0 MPa by means of a pressure-mixing process and drying curing conditions (80 °C, 24 h) compared with the geopolymers incorporating PAA and CPAM. A more homogeneous dispersion morphology was also observed by BSE and SEM for the 3% PVA-incorporated slag-based geopolymer. The FT-IR testing results confirmed the formation of a C–O–Si (Al) bond between PVA and the slag-based geopolymer. The deconvolution of the Q3 and Q2(1Al) species obtained by 29Si NMR testing manifested the addition of PVA and increased the length of the silicon backbone chain in the geopolymer. These findings confirmed that a composite geopolymer with high toughness can be produced based on the interpenetrating network structure formed between organic polymers and inorganic geopolymer.

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“…It should be noted that not only fly ash but also other aluminosilicate materials [11,12,14,17,24], such as different types of slags [25,26] or metakaolin [26][27][28][29][30], can be applied as starting materials for geopolymers. However, fly ashes from different sources [26,31,32], mixtures made of different fly ashes [33] or compositions of fly ash and other materials [34] still arouse interest.…”

Section: Introductionmentioning

confidence: 99%

Comparative investigation of reactivity of different kinds of fly ash in alkaline media

Wilińska

Pacewska

2019

J Therm Anal Calorim

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Comparison of the influence of temperature and different alkali activators on the reactivity of two types of fly ash (conventional, fluidized) was presented. The main emphasis was put on fluidized fly ash as potential component of binding mixtures containing low amount of cement. Conventional fly ash was used as a reference. It was found that for these materials the key differences affecting products of activation are: availability of calcium and sulfate ions as well as structure of fly ash grains influencing dissolution of aluminate and silicate species. Fluidized fly ash, contrary to conventional fly ash, undergoes reaction in 0.1 M solutions of hydroxides forming mainly ettringite. In the case of 4 M hydroxides, both fly ashes undergo hydration processes. Conventional fly ash formed mainly amorphous aluminosilicate gel, while fluidized fly ash may create zeolitic products especially in the case of elevated temperature of early hydration. Sulfate and alkali ions can be incorporated into aluminosilicate structure of new formed products; however, this process depends strictly on the type of used hydroxide and its concentration. The presence of Ca(OH) 2 , carbonates and alkali sulfates was also registered in the case of hydrated fluidized fly ash.

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Intrinsic parameters involved in the synthesis of metakaolin based geopolymer: Microstructure analysis

Cited by 16 publications

References 34 publications

Thermal, Mechanical and Microstructural Analysis of Metakaolin Based Geopolymers

Thermal, Mechanical and Microstructural Analysis of Metakaolin Based Geopolymers

The Mechanical Performance and Reaction Mechanism of Slag-Based Organic–Inorganic Composite Geopolymers

Comparative investigation of reactivity of different kinds of fly ash in alkaline media

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