Effects of sodium chloride on the mechanical strength of alkali activated volcanic ash and slag pastes under room and elevated temperatures

Ghadir, Pooria; Razeghi, Hamid Reza

doi:10.1016/j.conbuildmat.2022.128113

Cited by 28 publications

(19 citation statements)

References 73 publications

(140 reference statements)

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“…Numerous flakes were arranged into solid structures, while the geopolymer mortar's surface exhibited minimal porosity, indicating a compact structure. The hydration product of N-A-S-H and C-S-H was formed, attributed to small granular bodies contacting each other, and suspended in a lamellar matrix [36,37]. These assumptions corresponded with the high compressive strength results from T5 mortar mixtures (A2B1C2D3E4).…”

Section: Sem Analysismentioning

confidence: 57%

“…The initial material observed the crystalline phases of quartz, cristobalite, alunite, anorthite, and maghemite, whereas calcite, albite, and akermanite were formed in calcite, albite, and akermanite geopolymer mortar. This change indicates the formation of aluminosilicate hydrate gel, which has been identified as the N-A-S-H and C-S-H formation phases, resulting in an increase in the compressive strength of the mortar and a denser microstructure of the sample [4,36].…”

Section: Xrd Analysismentioning

confidence: 99%

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Synthesis of Volcanic Ash-based Geopolymer Mortar Designed by the Taguchi Method

Karolina

Tarigan²,

Johari³

et al. 2022

Civ Eng J

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This study focuses on the geopolymer synthesized from Mount Sinabung’s volcanic ash. The compressive strength of the geopolymer was determined by optimizing five factors using the Taguchi method’s L16 array. The five factors included: volcanic ash wt.%, Sodium silicate (Na2SiO3) wt.%, Sodium hydroxide (NaOH) concentration (mole), Na2SiO3/NaOH wt.% and water/binder (w/b) wt.%. A total of 16 mixtures were prepared per the L16 array and evaluated on five levels to obtain the optimum mixture. The main findings of this study revealed that A2B1C2D3E4 produced the highest compressive strength of 79.625 MPa after three days of curing time, while A4B2C3D1E4 produced the lowest compressive strength of 41.93 MPa. The signal-to-noise (S/N) ratio analysis from the Taguchi method shows that the factor of Na2SiO3 has a greater impact on compressive strength. The X-ray diffraction (XRD) result for the geopolymer mortar revealed the formation of aluminosilicate type (N-A-S-H) and calcium silicate (C-S-H) gels, whereas the Scanning Electron Microscopy (SEM) result exhibited numerous pores and a denser structure. These characterization results demonstrated that the polymerization of volcanic ash mortar from Sinabung successfully conserves natural resources. Doi: 10.28991/CEJ-2022-08-11-016 Full Text: PDF

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Section: Sem Analysismentioning

confidence: 57%

Section: Xrd Analysismentioning

confidence: 99%

Synthesis of Volcanic Ash-based Geopolymer Mortar Designed by the Taguchi Method

Karolina

Tarigan²,

Johari³

et al. 2022

Civ Eng J

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“…The lack of access to fresh water and the high cost of providing fresh water in soil improvement projects have caused researchers to consider the use of seawater as an economic option in large scale projects [1]. Recently, seawater is being used more and more in soil stabilization techniques including deep mixing and jet grouting to reduce fresh water consumption.…”

Section: Introductionmentioning

confidence: 99%

Effect of Seawater on the Mechanical Strength of Geopolymer/Cement Stabilized Sandy Soils

Samadi¹,

Ghodrati²,

Ghadir³

2023

Proceedings of the TMIC 2022 Slope Stability Conference (TMIC 2022)

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Freshwater supply for stabilizing sandy soils is one of the significant challenges in coastal regions. On the other hand, Ordindary Portland cement (OPC) has several limitations in the exposure to saline environments. Geopolymers, as environmentally friendly soil stabilizers, have been widely used in soil stabilization research. In this paper, the effects of natural seawater (SW) on the mechanical and microstructural properties of Portland cement/geopolymer stabilized sandy soils were studied. The soil samples were prepared with freshwater as reference samples. The impacts of binder type, slag replacement, curing duration, and curing conditions on the mechanical strength of stabilized soil samples were investigated. SEM images were used for microstructural analysis of the geopolymer stabilized soil samples. The results indicated that the use of seawater in stabilizing soil resulted in higher strength development in short-term (28 days) compared to the distilled water-based samples. However, seawater adversely affected the soil's long-term (90 days) strength. In addition, the strength of slag-based samples was generally higher than the strength of OPC and VA-based samples. Therefore, alkali-activated slag can be a potential replacement for OPC paste in stabilizing sandy soils. The SEM images revealed that using seawater led to the alteration of cementitious gels in comparison to distilled water.

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“…In the study of chloride binding in cementitious materials, the internal chloride ions are mainly realized by using sea sand, seawater, or adding chloride salts such as sodium chloride, calcium chloride, and magnesium chloride [ 25 , 26 , 27 , 28 , 29 ]. The TETS contains soluble chloride salts such as CaCl 2 and MgCl 2 , which have a high content of chloride ions and a complex existence status.…”

Section: Introductionmentioning

confidence: 99%

Influences of Friedel’s Salt Produced by CaO-Activated Titanium-Extracted Tailing Slag on Chloride Binding

et al. 2023

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Titanium-extracted tailing slag (TETS) has high activity, but the content of chloride ions is high. To effectively bind the chloride ions, CaO was used to activate the TETS, and the solidified cementitious material of CaO-activated TETS was prepared. The effects of CaO content and curing age on the strength of solidified samples, chloride binding capacity, and chloride binding mechanism were studied. By means of XRD, FTIR, SEM, and EDS, the hydration reaction products, microstructure, morphology, and micro-components of the solidified sample were characterized. The results show that the chloride ions can be effectively bound by using CaO to activate TETS with higher mechanical strength. When the CaO content is 10 wt%, the strength of the 28-day-cured body can reach more than 20 MPa, the chloride ion binding amount is 38.93 mg/g, and the chloride binding rate is as high as 68%. The new product phases of the solidified sample are mainly Friedel’s salt (FS) and calcite, in which the amount of FS production and the degree of crystal development are affected by the CaO content and curing age. The chloride binding ions in the solidified sample are mainly the chemical binding by FS. The FS diffraction peak strength increases with the increase of CaO content and curing age, but the calcite diffraction peak strength is less affected by them. FS mainly accumulates and grows in the pores of the solidified sample. It can optimize the pore structure of the solidified sample and improve the strength of the solidified sample while binding chloride ions. The results can provide useful information for the resource utilization of chlorine-containing TETS, the improvement of durability of Marine concrete, and the application of sea sand in concrete.

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Effects of sodium chloride on the mechanical strength of alkali activated volcanic ash and slag pastes under room and elevated temperatures

Cited by 28 publications

References 73 publications

Synthesis of Volcanic Ash-based Geopolymer Mortar Designed by the Taguchi Method

Synthesis of Volcanic Ash-based Geopolymer Mortar Designed by the Taguchi Method

Effect of Seawater on the Mechanical Strength of Geopolymer/Cement Stabilized Sandy Soils

Influences of Friedel’s Salt Produced by CaO-Activated Titanium-Extracted Tailing Slag on Chloride Binding

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