The Influence Mechanism of Ettringite Crystals and Microstructure Characteristics on the Strength of Calcium-Based Stabilized Soil

Han, Youmin; Xia, Junwu; Chang, Hongfei; Xu, Jun

doi:10.3390/ma14061359

Cited by 20 publications

(7 citation statements)

References 30 publications

(68 reference statements)

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“…When the coal gangue was modified with alkali situation (in Figure 2d), the surface structure became complicated and clusters (C-S-H gels) occurred on the surface of Al-CG; thus, the potential gelation activity was improved [55]. Additionally, some small needle-shaped crystals (AFt) could be detected in the pores, and the results were consistent with the results of Mola Abasi et al [56] and Han et al [57], which make the surface structure more complicated; thus, the adsorption process was facilitated. The SEM images were consistent with the XRD results.…”

Section: Sem Analysissupporting

confidence: 86%

Adsorption and Desorption of Coal Gangue toward Available Phosphorus through Calcium-Modification with Different pH

Min

Jiang

et al. 2022

Minerals

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The chemical reaction between calcium ions (Ca2+) and phosphate in the soil is the main way to maintain the availability of soil phosphorus. Thus, we believe stimulating coal gangue with Ca2+ solution would be an effective way to improve its adsorption and desorption capacity toward phosphate. In order to explore the effects of different pH of Ca2+ solution on the modified effect of coal gangue, we conducted mechanical grinding (<1 mm), high temperature calcination (800 °C), and the stimulation of Ca2+ solution with different pH (2, 7, 13), to prepare acidic calcium-modified coal gangue (Ac-CG) (Ac-CG, acidic calcium-modified coal gangue; Ne-CG, neutral calcium-modified coal gangue; Al-CG, alkali calcium-modified coal gangue; RCG, raw coal gangue), neutral calcium-modified coal gangue (Ne-CG), and alkali calcium-modified coal gangue (Al-CG); raw coal gangue (RCG) was regarded as the control. The results indicated that Al-CG had better phosphate adsorption (3.599 mg g−1); this favorable adsorption performance of Al-CG was related to the formation of hydrated calcium silicate gel and ettringite, which provided more Ca2+, Al3+, and hydroxyl groups, and a larger specific surface area (9.497 m2 g−1). Moreover, Al-CG not only held more phosphate but also maintained its availability longer for plants. It is suggested that stimulating coal gangue with Ca2+ solution under alkaline conditions is a perfect way to enhance its adsorption and desorption capacity toward phosphate; the Al-CG we prepared could be used as filling material and soil conditioner in the reclamation area.

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Section: Sem Analysissupporting

confidence: 86%

Adsorption and Desorption of Coal Gangue toward Available Phosphorus through Calcium-Modification with Different pH

Min

Jiang

et al. 2022

Minerals

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“…13. Zeolite-like crystal structure is seen in XRD patterns [86,[89][90][91]. In the detailed examination of the XRD patterns, ZSM-11 calcined formation was observed around 8.8° 2theta.…”

Section: Compressive Strength Test Resultsmentioning

confidence: 87%

The effect of micro-SiO2 and micro-Al2O3 additive on the strength properties of ceramic powder-based geopolymer pastes

Kaya

2021

J Mater Cycles Waste Manag

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In this study, the effect of micro-SiO 2 (S) and micro-Al 2 O 3 (A) additives on the strength of geopolymer pastes was investigated. Micro S + A are added to the raw ceramic powder (CP) by weight. NaOH is used as activator. The ratio of NaOH is adjusted to contain 3%, 6% and 9% sodium (Na) in proportion to the binder weight. CP is mixed with micro S, micro A and NaOH + water in a standard cement mixer, it is placed in standard molds of 40 mm × 40 mm × 160 mm. The molds were wrapped in a fireproof oven bag and kept in the oven at 105 °C for 24 h. As a result of the mechanical tests on the samples compressive strength between 3.53 and 17.97 MPa were determined in the samples containing micro S and micro A. An increase in compressive strength was observed with the increase of S/A and (S + A)/CP ratio in the samples. As a result of the regression analysis, it was concluded that 1.60% for S/A, 8.52% for (S + A)/CP and 6.74% for Na in geopolymer pastes could be the optimum mixing ratio.

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“…The AFt peak of W2L1-7d and W2L3-7d is almost the same, with little difference. However, when it comes to the influence of the CaO content in lime, it can be found from Figure 9a,b that the amorphous C-S-H gels increase with more CaO content in lime, which might due to the fact that more CaO participates in the hydrate reaction, facilitating the formation of C-S-H gels [31]. Comparing the thermogravimetric peaks (Figure 7) and the morphologies (Figure 9a,c) of W3L1-7d with W2L1-7d, the peak of AFt becomes slightly weaker and the microstructure becomes looser as the water increases.…”

Section: Hydration Mechanismsmentioning

confidence: 97%

“…As depicted in Figure 7, the thermogravimetric results show that the mass-loss peak temperatures of different mixtures and curing ages occur at 86.5~96.0 • C, 228.5~237.7 • C, and 651.0~667.0 • C, corresponding to the dehydrations of ettringite (AFt) crystal and aluminum gel (AH 3 ), together with the decarbonation of CaCO 3 , respectively [29][30][31]. Part of CaCO 3 is generated by a carbonization reaction of Ca(OH) 2 [30,31], and the other part is a small amount of CaCO 3 contained in the raw material lime L1 (Table 1). In addition, the images (Figure 8) obtained from SEM and EDS exhibit the morphology and element distribution of the mixture W2L1-28d.…”

Section: Hydration Mechanismsmentioning

confidence: 99%

The Relationship between Compressive Strength and Pore Structure of the High Water Grouting Material

Han

Xia

et al. 2021

Crystals

Self Cite

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To elucidate the relationship between compressive strength and pore structure of the high water grouting material with different water-binder ratios and CaO contents, the compressive strength was tested while pore structure including pore characteristic parameters and pore diameter distribution were investigated by BET, MIP, and 3D-XRM. Moreover, the evolution of hydration products was observed by TGA and SEM, illustrating the reactive mechanism of the material. Furthermore, the grey correlation coefficients between compressive strength and pore structure parameters were illustrated according to the grey correlation theory. The results show that CaO content in lime is proportional to the compressive strength with the water-binder ratio of 1.0 or 1.5, while the inverse trend appears with the water-binder ratio of 2.0. The high water grouting material belongs to the macropore material with the pores mainly within 100 nm to 2 μm. Its hydration products contain ettringite crystals, aluminum gels, and C-S-H gels. The productions of the hydration products are positively correlated with its compressive strength. In addition, the compressive strength of the high water grouting material is closely related to the pore characteristic parameters and the pore size distribution, especially the porosity, the most probable pore diameter, and the pore volumes within 100~500 nm and 10~100 nm.

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The Influence Mechanism of Ettringite Crystals and Microstructure Characteristics on the Strength of Calcium-Based Stabilized Soil

Cited by 20 publications

References 30 publications

Adsorption and Desorption of Coal Gangue toward Available Phosphorus through Calcium-Modification with Different pH

Adsorption and Desorption of Coal Gangue toward Available Phosphorus through Calcium-Modification with Different pH

The effect of micro-SiO2 and micro-Al2O3 additive on the strength properties of ceramic powder-based geopolymer pastes

The Relationship between Compressive Strength and Pore Structure of the High Water Grouting Material

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