Strength Development and Elemental Distribution of Dolomite/Fly Ash Geopolymer Composite under Elevated Temperature

Azimi, Emy Aizat; Abdullah, Mohd Mustafa Al Bakri; Vizureanu, Petrică; Salleh, Mohd Arif Anuar Mohd; Sandu, Andrei Victor; Chaiprapa, Jitrin; Yoriya, Sorachon; Kamarudin, Hussin; Aziz, Ikmal Hakem

doi:10.3390/ma13041015

Cited by 46 publications

(25 citation statements)

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“…Among all studied alkali-activated binders, the GB-1 specimens had the highest initial content of needle-like crystals of sodium carbonate hydrate phase in the composition ( Figure 4 a), and with a temperature increase transformed to amorphous substance to nanosized crystalline alumosilicate phases of nepheline, as has also been reported by other authors [ 18 , 22 , 38 ]. For all alkali-activated mixes, an increase in temperature to 600 °C and 800 °C allowed for better solubility of alumosilicate component in alkaline media, and therefore the formation of an additional vitreous phase that contributed to the formation of a denser matrix.…”

Section: Resultssupporting

confidence: 83%

The Correlation of Temperature-Mineral Phase Transformation as a Controlling Factor of Thermal and Mechanical Performance of Fly Ash-Based Alkali-Activated Binders

Kozhukhova

Zhernovskaya

et al. 2020

Materials

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This research focuses on an evaluation of mineral phase and structure transformations in Class F fly ash-based geopolymer systems. The research also studies the strength response of geopolymers when exposed to temperatures between 25 and 800 °C. The purpose of this research is to understand the processes that occur in alkali-activated systems within a wide range of high-working temperatures. The XRD, SEM, and DTA/TG analyses performed for the alkali-activated compositions after exposure to different temperatures confirmed a direct correlation of structural transformations with strength performance. The detrimental effect of sodium hydrocarbonate Na3(HCO3)(CO3) 2H2O or trona contained in one of the fly ash products was observed for the corresponding alkali-activated composite under high-temperature exposure between 600 and 800 °C. It was also detected that a high-temperature interval of 400–800 °C created favorable conditions that helped to form nanosized nepheline crystals and an additional vitreous substance that also contributed to a denser alkali-activated matrix.

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Section: Resultssupporting

confidence: 83%

The Correlation of Temperature-Mineral Phase Transformation as a Controlling Factor of Thermal and Mechanical Performance of Fly Ash-Based Alkali-Activated Binders

Kozhukhova

Zhernovskaya

et al. 2020

Materials

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“…The position change of the band is attributed to the internal vibrations of the sialates tetrahedra (Si-O-Al, Si-O-Al-O-Si-O, or Si-O-Al-O-Si-O-Si-O) resulting from geopolymerization [ 24 ]. Moreover, band II is also shifted to low frequencies (2) as a result of the increase in OH − groups concentration on the analyzed surface and also due to Al 3+ atoms penetration into the initial Si-O-Si structure forming the N-A-S-H and C-A-S-H phases, a phenomenon specific to zeolites [ 43 ]. A high peak corresponds to a high rate of the aluminum atom in the [SiO 4 ] 4− group penetration, i.e.…”

Section: Resultsmentioning

confidence: 99%

Revealing the Influence of Microparticles on Geopolymers’ Synthesis and Porosity

et al. 2020

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Geopolymers are zeolites like structures based on hydrated aluminosilicates units of SiO4 and AlO4. These units, known as poly(sialate), poly(sialate)-siloxo or poly(sialate)-disiloxo are chemically balanced by the group I cations of K+, Li+, or Na+. Simultaneously, the chemical reaction of formation, known as geopolymerization, governs the orientation of the unit, generating mesoporous structures. Multiple methods can be used for pore structure and porosity characterization. Among them, nuclear magnetic resonance (NMR) relaxometry allows the detection of the porous structure in a completely nonperturbative manner. NMR relaxometry may be used to monitor the relaxation of protons belonging to the liquid molecules confined inside the porous structure and, thus, to get access to the pore size distribution. This monitoring can take place even during the polymerization process. The present study implements transverse relaxation measurements to monitor the influence introduced by the curing time on the residual liquid phase of geopolymers prepared with two different types of reinforcing particles. According to our results, the obtained geopolymers contain three types of pores formed by the arrangement of the OH− and Si groups (Si-OH), Si-O-Si groups, Si-O-Al groups, and Si-O rings. After 48 days, the samples cured for 8 h show a high percentage of all three types of pores, however, by increasing the curing time and the percentage of reinforcing particle, the percent of pores decrease, especially, the gel pores.

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“…In order to obtain higher compressive strengths, several authors have added different aggregates to geopolymeric mixtures [41], such as sand [42,43], granite [44], gravel, sawdust [45], dolomite [46], glass [47][48][49][50][51], recycled materials [52], among others. On the other hand, it has been shown that milling of the blend of raw materials produced hydraulic cements with improved compressive strength when compared with separately milled raw materials that were blended after milling [53].…”

Section: Molar Ratiosmentioning

confidence: 99%

Factors Affecting the Compressive Strength of Geopolymers: A Review

et al. 2021

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Geopolymers are created by mixing a source of aluminosilicates, which can be natural or by-products from other industries, with an alkaline solution. These materials based on by-products from other industries have proven to be a less polluting alternative for concrete production than ordinary Portland cement (OPC). Geopolymers offer many advantages over OPC, such as excellent mechanical strength, increased durability, thermal resistance, and excellent stability in acidic and alkaline environments. Within these properties, mechanical strength, more specifically compressive strength, is the most important property for analyzing geopolymers as a construction material. For this reason, this study compiled information on the different variables that affect the compressive strength of geopolymers, such as Si/Al ratio, curing temperature and time, type and concentration of alkaline activator, water content, and the effect of impurities. From the information collected, it can be mentioned that geopolymers with Si/Al ratios between 1.5 and 2.0 obtained the highest compressive strengths for the different cases. On the other hand, high moderate temperatures (between 80 and 90 °C) induced higher compressive strengths in geopolymers, because the temperature favors the geopolymerization process. Moreover, longer curing times helped to obtain higher compressive strengths for all the cases analyzed. Furthermore, it was found that the most common practice is the use of sodium hydroxide combined with sodium silicate to obtain geopolymers with good mechanical strength, where the optimum SS/NaOH ratio depends on the source of aluminosilicates to be used. Generally speaking, it was observed that higher water contents lead to a decrease in compressive strength. The presence of calcium was found to be favorable in controlled proportions as it increases the compressive strength of geopolymers, on the other hand, impurities such as heavy metals have a negative effect on the compressive strength of geopolymers.

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Strength Development and Elemental Distribution of Dolomite/Fly Ash Geopolymer Composite under Elevated Temperature

Cited by 46 publications

References 47 publications

The Correlation of Temperature-Mineral Phase Transformation as a Controlling Factor of Thermal and Mechanical Performance of Fly Ash-Based Alkali-Activated Binders

The Correlation of Temperature-Mineral Phase Transformation as a Controlling Factor of Thermal and Mechanical Performance of Fly Ash-Based Alkali-Activated Binders

Revealing the Influence of Microparticles on Geopolymers’ Synthesis and Porosity

Factors Affecting the Compressive Strength of Geopolymers: A Review

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