Effect of high-temperature on the microstructure of alkali-activated binder

Ramagiri, Kruthi Kiran; Kar, Arkamitra

doi:10.1016/j.matpr.2020.01.093

Cited by 28 publications

(16 citation statements)

References 16 publications

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“…Moreover, the main band for the asymmetrical stretching vibration of Si-O-Si and Si-O-Al broadened at elevated temperatures. This was associated with the structural disorder, which was in parallel with previous studies [10,60]. Moreover, an increase in transmittance percentage of the bands at ~3300 cm −1 and ~1650 cm −1 was observed, demonstrating the decrease in the intensity of H-O-H and -OH bonding, and proving the full dehydration of geopolymers at high temperatures.…”

Section: Functional Group Identificationsupporting

confidence: 86%

“…Moreover, the main band for the asymmetrical stretching vibration of Si-O-Si and Si-O-Al broadened at elevated temperatures. This was associated with the structural disorder, which was in parallel with previous studies [10,60]. Moreover, an increase in Figure 16 displays the FTIR spectra of the FAS and FAB8 geopolymers at elevated temperatures.…”

Section: Functional Group Identificationsupporting

confidence: 82%

“…The three-dimensional framework of SiO 4 and AlO 4 provides geopolymer remarkable physical and mechanical properties due to its ceramic-like characteristics [9]. In fact, geopolymers have excellent thermal properties, and extended heating could facilitate the extent of geopolymerization, yielding the formation of a geopolymer matrix, thereby enhancing the mechanical strength of the geopolymer [10]. Furthermore, according to past literature, the thermomechanical properties of geopolymers could be enhanced using additives [5], fiber reinforcement [11,12] and blended geopolymers with the incorporation of two or more precursor aluminosilicates [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

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Improvements of Flexural Properties and Thermal Performance in Thin Geopolymer Based on Fly Ash and Ladle Furnace Slag Using Borax Decahydrates

et al. 2022

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This paper elucidates the influence of borax decahydrate addition on the flexural and thermal properties of 10 mm thin fly ash/ladle furnace slag (FAS) geopolymers. The borax decahydrate (2, 4, 6, and 8 wt.%) was incorporated to produce FAB geopolymers. Heat treatment was applied with temperature ranges of 300 °C, 600 °C, 900 °C, 1000 °C and 1100 °C. Unexposed FAB geopolymers experienced a drop in strength due to a looser matrix with higher porosity. However, borax decahydrate inclusion significantly enhanced the flexural performance of thin geopolymers after heating. FAB2 and FAB8 geopolymers reported higher flexural strength of 26.5 MPa and 47.8 MPa, respectively, at 1000 °C as compared to FAS geopolymers (24.1 MPa at 1100 °C). The molten B2O3 provided an adhesive medium to assemble the aluminosilicates, improving the interparticle connectivity which led to a drastic strength increment. Moreover, the borax addition reduced the glass transition temperature, forming more refractory crystalline phases at lower temperatures. This induced a significant strength increment in FAB geopolymers with a factor of 3.6 for FAB8 at 900 °C, and 4.0 factor for FAB2 at 1000 °C, respectively. Comparatively, FAS geopolymers only achieved 3.1 factor in strength increment at 1100 °C. This proved that borax decahydrate could be utilized in the high strength development of thin geopolymers.

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Section: Functional Group Identificationsupporting

confidence: 86%

“…Moreover, the main band for the asymmetrical stretching vibration of Si-O-Si and Si-O-Al broadened at elevated temperatures. This was associated with the structural disorder, which was in parallel with previous studies [10,60]. Moreover, an increase in Figure 16 displays the FTIR spectra of the FAS and FAB8 geopolymers at elevated temperatures.…”

Section: Functional Group Identificationsupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Improvements of Flexural Properties and Thermal Performance in Thin Geopolymer Based on Fly Ash and Ladle Furnace Slag Using Borax Decahydrates

et al. 2022

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“…These observations are corroborated with the findings from FITR analyses as described in the next section. The 0.35 w/s AAB-treated jute has unevenly distributed voids, and the textile surface is partially coated with a vitreous network-like sodium aluminosilicate hydrate (N-A-S-H) matrix [58]. Additionally, Fig.…”

Section: Surface Morphologymentioning

confidence: 99%

Experimental Investigations on Strength and Durability of Alkali-Activated Binder-Treated Natural Jute Geotextile

Chakravarthy

GuhaRay

Kar

2021

Int. J. of Geosynth. and Ground Eng.

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The application of natural fibers for improving the strength of soft soil is gaining recent global popularity to achieve sustainable development. However, the biodegradability of natural fibers within 6-12 months is the main source of a hindrance towards its practical implementation. Treatment of natural fibers with antimicrobial chemicals, plant-derived oils, acetylation, and bitumen coating results in improving the durability of natural fibers, but these methods are costly and may cause leaching. The current work suggests a unique treatment approach for natural jute geotextiles that involves treating these geotextiles with an alkali-activated binder (AAB) to improve their strength and durability. Fly ash, an aluminosilicate-rich industrial waste, reacts with a sodium silicate and sodium hydroxide-based activator solution to form AAB. The water-to-solids ratios (w/s) are maintained at 0.30, 0.35, 0.4, 0.45, and 0.50 for treatment of the fibers. The untreated and treated natural geotextiles are subjected to different durability tests including soil burial, compost burial, exposure to acids and alkalis, and hydrolysis of water for three different periods of 30, 60, and 90 days. The durability performance is assessed by analyzing the surface texture, surface morphology, change in chemical bonds, weight loss, tensile strength, and elongation at failure (fiber breaking). It is observed from the durability studies that the AAB treatment makes the jute geotextile harder and more resistant to exposure to different chemicals. It is also been determined that jute coated with an AAB of 0.35 w/s ratio degrades the least.

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“…In such conditions, the proper understanding of the behavior of geopolymer materials when exposed to high temperatures is essential. In past literature, there have been wide investigations on the effect of thermal exposure on the mechanical strength of geopolymers [ 5 , 6 , 7 , 8 ]. Indeed, geopolymer decreased its strength under thermal loading.…”

Section: Introductionmentioning

confidence: 99%

Elevated-Temperature Performance, Combustibility and Fire Propagation Index of Fly Ash-Metakaolin Blend Geopolymers with Addition of Monoaluminium Phosphate (MAP) and Aluminum Dihydrogen Triphosphate (ATP)

et al. 2021

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Thermal performance, combustibility, and fire propagation of fly ash-metakaolin (FA-MK) blended geopolymer with the addition of aluminum triphosphate, ATP (Al(H2PO4)3), and monoaluminium phosphate, MAP (AlPO4) were evaluated in this paper. To prepare the geopolymer mix, fly ash and metakaolin with a ratio of 1:1 were added with ATP and MAP in a range of 0–3% by weight. The fire/heat resistance was evaluated by comparing the residual compressive strengths after the elevated temperature exposure. Besides, combustibility and fire propagation tests were conducted to examine the thermal performance and the applicability of the geopolymers as passive fire protection. Experimental results revealed that the blended geopolymers with 1 wt.% of ATP and MAP exhibited higher compressive strength and denser geopolymer matrix than control geopolymers. The effect of ATP and MAP addition was more obvious in unheated geopolymer and little improvement was observed for geopolymer subjected to elevated temperature. ATP and MAP at 3 wt.% did not help in enhancing the elevated-temperature performance of blended geopolymers. Even so, all blended geopolymers, regardless of the addition of ATP and MAP, were regarded as the noncombustible materials with negligible (0–0.1) fire propagation index.

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Effect of high-temperature on the microstructure of alkali-activated binder

Cited by 28 publications

References 16 publications

Improvements of Flexural Properties and Thermal Performance in Thin Geopolymer Based on Fly Ash and Ladle Furnace Slag Using Borax Decahydrates

Improvements of Flexural Properties and Thermal Performance in Thin Geopolymer Based on Fly Ash and Ladle Furnace Slag Using Borax Decahydrates

Experimental Investigations on Strength and Durability of Alkali-Activated Binder-Treated Natural Jute Geotextile

Elevated-Temperature Performance, Combustibility and Fire Propagation Index of Fly Ash-Metakaolin Blend Geopolymers with Addition of Monoaluminium Phosphate (MAP) and Aluminum Dihydrogen Triphosphate (ATP)

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