Effects of elevated temperatures on the properties of ground granulated blast furnace slag (GGBFS) based geopolymer concretes containing recycled concrete aggregate

Topal, Özge; Karakoç, Mehmet Burhan; Özcan, Ahmet

doi:10.1080/19648189.2021.1871658

Cited by 14 publications

(5 citation statements)

References 39 publications

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“…This showed that the values were consistent when compared with the strengths of the samples. Topal et al 16 reported that these values of slag‐based geopolymer concretes kept at 800°C for 1 h were between 8.32 and 12.93 mm/min −0.5 .…”

Section: Resultsmentioning

confidence: 99%

“…The inorganic framework of geopolymers with high thermal stability is resistant up to 700-800 C. 5 There are studies investigating the performance of geopolymers under high temperatures depending on different parameters. In these studies, slag, [13][14][15][16][17][18] fly ash, 13,[19][20][21][22][23][24][25][26][27] rice husk ash, 25 volcanic tuff, 28 metakaolin, 29,30 and pumice 31,32 were used as source material. Sodium silicate, sodium hydroxide, potassium carbonate, and calcium hydroxide were used as alkali activators.…”

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confidence: 99%

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Effect of silica fume and waste rubber on the performance of slag‐based geopolymer mortars under high temperatures

Sağır

Karakoç

Özcan

et al. 2023

Structural Concrete

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In this study, the fire resistance of slag‐based geopolymer mortars was investigated and the effect of silica fume (SF) and waste rubber (WR) on this resistance was determined. In slag‐based geopolymer mortars activated using 12M NaOH solution, 0%, 5%, and 10% by weight SF was substituted for slag; 0%, 5%, 10%, and 15% WR by volume were substituted for fine aggregate. The samples that completed the curing period were exposed to temperatures of 250°C, 500°C, and 750°C for 1 h, and the mechanical (compressive, flexural and splitting tensile strengths, and impact resistance), physical (weight change and sorptivity) and microstructure (scanning electron microscopy [SEM] and energy dispersive spectroscopy [EDS]) properties of these samples were examined. The compressive strengths of the samples without WR were between 48.10 and 60.97 MPa, and the samples without SF were between 28.52 and 48.10 MPa. Strength losses at 750°C were between 51.5% and 73.5%. As the SF substitution increased, the samples' mechanical and physical properties improved, whereas as the WR substitution increased, the samples' mechanical and physical properties declined. While the SF substitution had a positive effect on the fire resistance of the samples, the WR substitution had a negative effect. It is thought that the choice of geopolymer binder as a binder in the mortar and the use of waste tires as aggregate contribute to the literature in terms of both preventing environmental pollution and ensuring the recycling of these materials.

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Effect of silica fume and waste rubber on the performance of slag‐based geopolymer mortars under high temperatures

Sağır

Karakoç

Özcan

et al. 2023

Structural Concrete

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“…This situation was also compatible with the deterioration of the strength capacity of the samples. Topal et al [78] observed that at 200 • C, the geopolymeric gel microstructure started degrading. They linked the decrease in the sample strength to these deteriorations.…”

Section: Edxmentioning

confidence: 99%

Thermal Behaviour and Microstructure of Self-Cured High-Strength Plain and Fibrous Geopolymer Concrete Exposed to Various Fire Scenarios

Ali,

Abid,

Tayşi

2023

Buildings

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The fire resistance of construction materials is an essential part of safety requirements in the construction industry. In this work, experimental investigations were conducted to understand the thermal behaviour, spalling, transfer characteristics, strength, and microstructures of self-cured high-strength plain (HSGC) and steel-fibre-reinforced geopolymer concrete (S–HSGC) under severe fire scenarios with peak temperatures of 275, 560, and 825 °C; the peak was maintained for a period of 120 min after reaching it. Forty-eight standard cylindrical specimens for each mixture were prepared to test and analyse their time–heat response, gradients, visual appearance, spalling, density change, water absorption, and compressive strength before and after fire exposure. Additionally, Scanning Electron Microscopy (SEM) along with Energy Dispersive X-ray Analysis (EDX) were utilised to analyse the internal structures and phase transformations. The thermal analysis showed that no cases of explosive spalling were recorded during sample exposure to various fires, while the used hook-end steel fibres had an influence on the considered test variables. The sample cores almost reached the target heat, and the thermal saturation degree at the peak ranged from 55 to 97%. The experimental findings also revealed slight surface cracking after exposure to 560 °C fires, while the surface cracking was more obvious for specimens exposed to 825 °C. Moreover, the residual compressive strength of the S–HSGC at various fires was noticeably 10.20% higher than that of the HSGC. Also, state-of-the-art research data were used to discuss the prediction model’s performance. The SEM and EDX results showed that the self-cured geopolymerization process was effective and successful in producing gels, in addition to the significant phase transformations in microstructures at different fires. This study presented sophisticated data on the behaviour of HSGC and S–HSGC exposed to fires up to 825 °C.

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“…The novelty of this study lies in the activator used and the method of producing geopolymers. Most studies [ 24 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ] on geopolymer samples exposed to higher temperatures deal with sodium hydroxide and sodium silicate as activators. Although the sodium sources for alkaline are preferable for regular geopolymer applications, such as construction purposes, they fail to retain their amorphous nature at elevated temperature ranges.…”

Section: Introductionmentioning

confidence: 99%

Advanced Solid Geopolymer Formulations for Refractory Applications

Hussain,

Amritphale,

Matthews

et al. 2024

Materials

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Cement, as a construction material, has low thermal resistance, inherent fire resistance, and is incombustible up to a certain degree. However, the loss of its mechanical performance and spalling are its primary issues, and it thus cannot retain its performance in refractory applications. The present study explores the performance of geopolymer formulations that have excellent fire resistance properties for potential refractory applications. This study is unique, as it investigates advanced solid geopolymer formulations that need only water to activate and bind. Various solid geopolymer formulations with fly ash as a precursor; potassium hydroxide and potassium silicate as activators; and mullite and alumina as refractory aggregates were studied for their compressive strength at up to 1100 °C and compared with their two-part conventional liquid alkaline geopolymer counterparts. Advanced solid geopolymer formulations with mullite and alumina as refractory aggregates had mechanical strength values of 84 MPa and 64 MPa post-1100 °C exposure and were further exposed to ten thermal cycles of 1100 °C to study their fatigue resistance and post-exposure compressive strengths. The geopolymer sample with mullite as a refractory aggregate yielded 115.2 MPa compressive strength after the fourth cycle of exposure. This sample was also studied for its temperature distribution upon direct flame exposure. All the geopolymer formulations displayed a drop in compressive strength at 600 °C due to viscous sintering and then a rise in strength at 1100 °C due to phase transformation. X-ray diffraction studies revealed that the formation of crystalline phases such as leucite, sanidine, and annite were responsible for the superior strengths at 1100 °C for the alumina- and mullite-based geopolymer formulations.

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Effects of elevated temperatures on the properties of ground granulated blast furnace slag (GGBFS) based geopolymer concretes containing recycled concrete aggregate

Cited by 14 publications

References 39 publications

Effect of silica fume and waste rubber on the performance of slag‐based geopolymer mortars under high temperatures

Effect of silica fume and waste rubber on the performance of slag‐based geopolymer mortars under high temperatures

Thermal Behaviour and Microstructure of Self-Cured High-Strength Plain and Fibrous Geopolymer Concrete Exposed to Various Fire Scenarios

Advanced Solid Geopolymer Formulations for Refractory Applications

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