Thermo-mechanical characteristics of geopolymer mortar

Chithambaram, S. Jeeva; Kumar, Sanjay; Prasad, M. Mohan

doi:10.1016/j.conbuildmat.2019.04.051

Cited by 85 publications

(37 citation statements)

References 36 publications

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“…Effects of elevated temperatures on properties of geopolymer materials have been extensively studied [ 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. Geopolymers indicated a decrease in the mechanical strength when exposed to elevated temperatures [ 30 , 31 , 32 , 33 ]. Chithambaram et al [ 31 ] reported that the compressive strength of geopolymer mortar reduced and its mass loss increased with increasing sample heating temperature to 1000 °C.…”

Section: Introductionmentioning

confidence: 99%

“…Geopolymers indicated a decrease in the mechanical strength when exposed to elevated temperatures [ 30 , 31 , 32 , 33 ]. Chithambaram et al [ 31 ] reported that the compressive strength of geopolymer mortar reduced and its mass loss increased with increasing sample heating temperature to 1000 °C. Yang et al [ 32 ] showed a reduction in the compressive strength and Young’s modulus of geopolymer made of red mud slurry and class F fly ash with the temperature rise to 1000 °C.…”

Section: Introductionmentioning

confidence: 99%

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Study on Temperature-Dependent Properties and Fire Resistance of Metakaolin-Based Geopolymer Foams

Louda

Nam

et al. 2020

Polymers

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This paper presents temperature-dependent properties and fire resistance of geopolymer foams made of ground basalt fibers, aluminum foaming agents, and potassium-activated metakaolin-based geopolymers. Temperature-dependent properties of basalt-reinforced geopolymer foams (BGFs) were investigated by a series of measurements, including apparent density, water absorption, mass loss, drying shrinkage, compressive and flexural strengths, XRD, and SEM. Results showed that the apparent density and drying shrinkage of the BGFs increase with increasing the treated temperature from 400 to 1200 °C. Below 600 °C the mass loss is enhanced while the water absorption is reduced and they both vary slightly between 600 and 1000 °C. Above 1000 °C the mass loss is decreased rapidly, whereas the water absorption is increased. The compressive and flexural strengths of the BGFs with high fiber content are improved significantly at temperatures over 600 °C and achieved the maximum at 1200 °C. The BGF with high fiber loading at 1200 °C exhibited a substantial increase in compressive strength by 108% and flexural strength by 116% compared to that at room temperature. The enhancement in the BGF strengths at high temperatures is attributed to the development of crystalline phases and structural densification. Therefore, the BGFs with high fiber loading have extraordinary mechanical stability at high temperatures. The fire resistance of wood and steel plates has been considerably improved after coating a BGF layer on their surface. The coated BGF remained its structural integrity without any considerable macroscopic damage after fire resistance test. The longest fire-resistant times for the wood and steel plates were 99 and 134 min, respectively. In general, the BGFs with excellent fire resistance have great potential for fire protection applications.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study on Temperature-Dependent Properties and Fire Resistance of Metakaolin-Based Geopolymer Foams

Louda

Nam

et al. 2020

Polymers

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“…The partial replacement of fly ash by ground granulated blast-furnace slag strengthens the structure of the material and can also accelerate the curing of the geopolymer at room temperature. The addition of GGBFS increases the calcium content in the material structure, increases early strength, shortens the setting time at ambient temperature and increases the density and mechanical parameters of the binder [ 21 ]. In the case of certain geopolymer composites with a mixed FA-GGBFS binder, high tensile stress caused by shrinkage was observed, which increases the risk of cracks in the material at the early stage of curing [ 22 ].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Changes in the Microstructure of Geopolymer Mortar after Exposure to High Temperatures

Dudek

Sitarz

2020

Materials

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The inorganic structure formed at the stage of setting of the geopolymer binder ensures high durability of the material under high-temperature conditions. However, changes in the microstructure of the material are observed. The purpose of the study was to analyze changes in the structure of geopolymer mortar after exposure to high temperatures T = 200, 400, 600, 800, and 1000 °C. Mortars with a binder based solely on fly ash (FA) and mixed in the 1:1 ratio with a binder containing fly ash and ground granulated blast-furnace slag (GGBFS) were tested. The descriptions of their microstructures were prepared based on digital microscope observations, scanning electron microscope (SEM) observations, EDS (energy dispersive spectroscopy) analysis, and mercury intrusion porosimetry (MIP) porosity test results. Changes in the material due to high temperature were observed. The differences in the microstructure of the samples are also visible in the materials that were not exposed to temperature, which was influenced by the composition of the materials. Porosity increases with increasing annealing temperature. The distribution of individual pores also changes. In both materials, the proportion of pores larger than 1000 nm increases with the temperature increase. Moreover, the number of cracks and their width also increases, reaching 20 µm in the case of GGBFS. Furthermore, the color of geopolymers has changed. The obtained results extend the current state of knowledge in the field of changes in the microstructure of geopolymers subjected to high temperature.

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“…The free water was released in the form of vapor. The mass loss at this temperature range was observed in most of the geopolymer samples when heated [ 14 , 23 ]. The mass loss above 200 °C was because of the loss of structural water [ 24 ].…”

Section: Resultsmentioning

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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Thermo-mechanical characteristics of geopolymer mortar

Cited by 85 publications

References 36 publications

Study on Temperature-Dependent Properties and Fire Resistance of Metakaolin-Based Geopolymer Foams

Study on Temperature-Dependent Properties and Fire Resistance of Metakaolin-Based Geopolymer Foams

Analysis of Changes in the Microstructure of Geopolymer Mortar after Exposure to High Temperatures

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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