Mechanism of reactive magnesia – ground granulated blastfurnace slag (GGBS) soil stabilization

Reactive magnesia (MgO)-activated ground granulated blastfurnace slag (GGBS), with fixed GGBS dosages but varying MgO/GGBS ratios, was used for stabilization of two soils and compared with brucite (Mg(OH)2)-activated GGBS and hydrated lime (Ca(OH)2)-activated GGBS. A range of tests, including unconfined compressive strength testing, X-ray diffraction, and scanning electron microscopy, was conducted to study the mechanical, chemical, and microstructural properties of the stabilized soils, and then to investigate the mechanism of MgO–GGBS soil stabilization. Results indicate that the Mg(OH)2 had a minimal activating efficacy for GGBS-stabilized soil, while the reactive MgO yielded a higher activating efficacy than the Ca(OH)2. The activator–soil reactions in the stabilized soil slowed down the activating reaction rate for GGBS; this effect was less significant in MgO–GGBS-stabilized soil than in Ca(OH)2–GGBS-stabilized soil, and hence the GGBS hydration rate in the former was less reduced by the soil than the latter. The Mg2+ and OH− ions produced from MgO dissolution participated in the GGBS hydration reactions without precipitating Mg(OH)2. The common hydration products in all GGBS-stabilized soils were calcium silicate hydrate–like compounds. Additionally, hydrotalcite and calcite could be produced in MgO–GGBS- and Ca(OH)2–GGBS-stabilized soils, respectively, especially with a high activator/GGBS ratio.

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Carbonating magnesia for soil stabilization

Canadian Geotechnical Journal ◽

10.1139/cgj-2012-0364 ◽

2013 ◽

Vol 50 (8) ◽

pp. 899-905 ◽

Cited By ~ 53

Author(s):

Yaolin Yi ◽

Martin Liska ◽

Cise Unluer ◽

Abir Al-Tabbaa

Keyword(s):

Soil Stabilization ◽

Strength Development ◽

X Ray Diffraction ◽

X Ray ◽

Significant Strength ◽

Triaxial Cell ◽

Stabilized Soil ◽

Mechanical And Microstructural Properties ◽

Set Up ◽

Reactive Magnesia

This paper investigates the potential for carbonating reactive magnesia (MgO) to serve as a more sustainable soil stabilization method by providing rapid and significant strength development of the stabilized soil through absorbing substantial quantities of CO2. Gaseous CO2 was forced through laboratory-prepared reactive MgO-treated soil samples in a triaxial cell set-up, and their resulting mechanical and microstructural properties were investigated using unconfined compressive strength, X-ray diffraction, and scanning electron microscopy. The results showed that adequately carbonated MgO-treated soils could, in a few hours, reach a similar strength range to corresponding 28 day Portland cement (PC)-stabilized soils. Hydrated magnesium carbonates, namely nesquehonite and hydromagnesite–dypingite, were the main products of the carbonated MgO in the soil, and were responsible for the significant strength development.

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Toward E-selective Olefin Metathesis: Computational Design and Experimental Realization of Ruthenium Thio-Indolate Catalysts

Topics in Catalysis ◽

10.1007/s11244-021-01468-3 ◽

2021 ◽

Author(s):

Immanuel Reim ◽

Giovanni Occhipinti ◽

Karl W. Törnroos ◽

Deryn E. Fogg ◽

Vidar R. Jensen

Keyword(s):

Olefin Metathesis ◽

Density Functional ◽

Reaction Rate ◽

Computational Design ◽

X Ray Diffraction ◽

Functional Theory ◽

Experimental Realization ◽

X Ray ◽

The Common ◽

Ligand Orientation

AbstractThe selective transformation of 1-alkenes into E-olefins is a long-standing challenge in olefin metathesis. Density functional theory (DFT) calculations predict high E-selectivity for catalysts incorporating a bidentate, dianionic thio-indolate ligand within a RuXX’(NHC)(py)(= CHR) platform (NHC = N-heterocyclic carbene; py = pyridine). Such complexes are predicted to yield E-olefins by favoring anti-disposed substituents in the transition state expected to be rate-determining: specifically, that for cycloreversion of the metallacyclobutane intermediate. Three pyridine-stabilized catalysts Ru21a-c were synthesized, in which the thio-indolate ligand bears a H, Me, or Ph substituent at the C2 position, and the NHC ligand is the unsaturated imidazoline-2-ylidene Me2IMes (which bears N-mesityl groups and methyl groups on the C4,5 backbone). Single-crystal X-ray diffraction analysis of Ru21c confirms the ligand orientation required for E-selective metathesis, with the thio-indolate sulfur atom binding cis to the NHC, and the indolate nitrogen atom trans to the NHC. However, whereas the new complexes mediated metathetic exchange of their 2-thienylmethylidene ligand in the presence of the common metathesis substrates styrene and allylbenzene, no corresponding self-metathesis products were obtained. Only small amounts of 2-butene (73% (Z)-2-butene) were obtained in self-metathesis of propene using Ru21a. Detailed DFT analysis of this process revealed that product release is surprisingly slow, limiting the reaction rate and explaining the low metathesis activity. With the barrier to dissociation of (Z)-2-butene being lower than that of (E)-2-butene, the calculations also account for the observed Z-selectivity of Ru21a. These findings provide guidelines for catalyst redesign in pursuit of the ambitious goal of E-selective 1-alkene metathesis. Graphic abstract

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Strength Performance and Microstructure of Calcium Sulfoaluminate Cement-Stabilized Soft Soil

Sustainability ◽

10.3390/su13042295 ◽

2021 ◽

Vol 13 (4) ◽

pp. 2295

Author(s):

Hailong Liu ◽

Jiuye Zhao ◽

Yu Wang ◽

Nangai Yi ◽

Chunyi Cui

Keyword(s):

Soft Soil ◽

Hydration Product ◽

X Ray Diffraction ◽

Calcium Sulfoaluminate Cement ◽

Strength Performance ◽

X Ray ◽

Calcium Sulfoaluminate ◽

Stabilized Soil ◽

Calcium Silicates ◽

Hydrated Calcium

Calcium sulfoaluminate cement (CSA) was used to stabilize a type of marine soft soil in Dalian China. Unconfined compressive strength (UCS) of CSA-stabilized soil was tested and compared to ordinary Portland cement (OPC); meanwhile the influence of amounts of gypsum in CSA and cement contents in stabilized soils on the strength of stabilized soils were investigated. X-ray diffraction (XRD) tests were employed to detect generated hydration products, and scanning electron microscopy (SEM) was conducted to analyze microstructures of CSA-stabilized soils. The results showed that UCS of CSA-stabilized soils at 1, 3, and 28 d firstly increased and then decreased with contents of gypsum increasing from 0 to 40 wt.%, and CSA-stabilized soils exhibited the highest UCS when the content of gypsum equaled 25 wt.%. When the mixing amounts of OPC and CSA were the same, CSA-stabilized soils had a significantly higher early strength (1 and 3 d) than OPC. For CSA-stabilized soil with 0 wt.% gypsum, monosulfate (AFm) was detected as a major hydration product. As for CSA-stabilized soil with certain amounts of gypsum, the intensity of ettringite (Aft) was significantly higher than that in the sample hydrating without gypsum, but a tiny peak of AFm also could be detected in the sample with 15 wt.% gypsum at 28 d. Additionally, the intensity of AFt increased with the contents of gypsum increasing from 0 to 25 wt.%. When contents of gypsum increased from 25 to 40 wt.%, the intensity of AFt tended to decrease slightly, and residual gypsum could be detected in the sample with 40 wt.% gypsum at 28 d. In the microstructure of OPC-stabilized soils, hexagonal plate-shaped calcium hydroxide (CH) constituted skeleton structures, and clusters of hydrated calcium silicates (C-S-H) gel adhered to particles of soils. In the microstructure of CSA-stabilized soils, AFt constituted skeleton structures, and the crystalline sizes of ettringite increased with contents of gypsum increasing; meanwhile, clusters of the aluminum hydroxide (AH3) phase could be observed to adhere to particles of soils and strengthen the interaction.

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Study of UiO-66 and UiO-66 Modulated with Acetic Acid as the Adsorbent for Eriochrome Black T Dye

Indo J Chem Res ◽

10.30598//ijcr.2021.8-riz ◽

2021 ◽

Vol 8 (3) ◽

pp. 183-193

Author(s):

M. Anugrah Rizky Pambudi ◽

Nanda Prayogo ◽

Muhammad Nadjib ◽

Ratna Ediati

Keyword(s):

Acetic Acid ◽

Reaction Rate ◽

Metal Organic Framework ◽

X Ray Diffraction ◽

Adsorption Selectivity ◽

X Ray ◽

Langmuir Adsorption ◽

Eriochrome Black T ◽

Metal Organic ◽

Pseudo Second Order

UiO-66, as one of the metal-organic framework (MOF) compounds, has been used to treat some anionic and cationic dye waste. In order to determine the adsorption selectivity decisively, the synthesis of UiO-66 and UiO-66 modulated with acetic acid had been carried out, along with their adsorption tests for Eriochrome Black T (EBT) dye solution. The synthesis was performed by utilizing a solvothermal method with the reaction mixtures of zirconium (IV) chloride (ZrCl4) and terephthalic acid (H2BDC) as a ligand heated at 120 oC for 24 hours. Both UiO-66 (without acetic acid) and acetic acid modulated UiO-66 were obtained as a white powder. Acetic acid as a modulator was added and being investigated for the adsorption capability compared to the normal UiO-66. This study showed that normal UiO-66 exhibited better adsorption than acetic acid modulated UiO-66 with a mmol ratio of acetic acid:ligand varied from 50:1, 100:1, and 150:1. Acetic acid modulated UiO-66 with a mmol ratio of 50 exhibited the best crystallinity as observed by using x-ray diffraction. It can be concluded that the adsorption of EBT using normal and acetic acid modulated UiO-66 obeyed the pseudo-second-order reaction rate law as well as the Langmuir adsorption isotherm pattern.

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Fibrous Minerals and Synthetic Fibers

Asbestos and Other Fibrous Materials ◽

10.1093/oso/9780195039672.003.0005 ◽

1989 ◽

Author(s):

H. Catherine W. Skinner ◽

Malcolm Ross ◽

Clifford Frondel

Keyword(s):

Crystal Structure ◽

Chemical Composition ◽

Chemical Properties ◽

Type Specimen ◽

Mineral Species ◽

X Ray Diffraction ◽

X Ray ◽

Synthetic Fibers ◽

Fibrous Minerals ◽

The Common

A mineral is a naturally occurring, crystalline inorganic compound with a specific chemical composition and crystal structure. Minerals are commonly named to honor a person, to indicate the geographic area where the mineral was discovered, or to highlight some distinctive chemical, crystallographic, or physical characteristic of the substance. Each mineral sample has some obvious properties: color, shape, texture, and perhaps odor or taste. However, to determine the precise composition and crystal structure necessary to accurately identify the species, one or several of the following techniques must be employed: optical, x-ray diffraction, transmission electron microscopy and diffraction, and chemical and spectral analyses. The long history of bestowing names on minerals has provided some confusing legacies. Many mineral names end with the suffix “ite,” although not most of the common species; no standard naming practice has ever been adopted. Occasionally different names have been applied to samples of the same mineral that differ only in color or shape, but are identical to each other in chemical composition and crystal structure. These names, usually of the common rock-forming minerals, are often encountered and are therefore accepted as synonyms or as varieties of bona fide mineral species. The Fibrous Minerals list (Appendix 1) includes synonyms. A formal description of a mineral presents all the physical and chemical properties of the species. In particular, distinctive attributes that might facilitate identification are noted, and usually a chemical analysis of the first or “type” specimen on which the name was originally bestowed is included. As an example, the complete description of the mineral brucite (Mg(OH)2), as it appears in Dana’s System of Mineralogy, is presented as Appendix 3. Note the complexity of this chemically simple species and the range of information available. In the section on Habit (meaning shape or morphology) both acicular and fibrous forms are noted. The fibrous variety, which has the same composition as brucite, is commonly encountered (see Fig. 1.1D) and is known by a separate name, “nemalite.” Tables to assist in the systematic determination of a mineral species are usually based on quantitative measurements of optical properties (using either transmitted or reflected light, as appropriate) or on x-ray diffraction data.

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Kristallchemische Analyse der Stereochemie des Kations und Anions in Bis(triphenylphosphin)iminium-di(phthalocyaninato)metallaten der Selenen Erden, (PNP)[Ln(Pc2-)2]•xH2O (Ln = La, Gd, Tm; x ≤ 0,5) / Crystalchemical analysis of the stereochemistry of the cations and anions in bis(triphenylphosphine)iminium di(phthalocyaninato)metalates of the rare earth elements, (PNP)[Ln(Pc2-)2]•xH2O (Ln = La, Gd, Tm; x ≤ 0,5)

Zeitschrift für Naturforschung B ◽

10.1515/znb-1994-0615 ◽

1994 ◽

Vol 49 (6) ◽

pp. 812-820 ◽

Cited By ~ 32

Author(s):

Mohsen Safarpour Haghighi ◽

Andreas Franken ◽

Heiner Homborg

Keyword(s):

Structural Characteristics ◽

Steric Effects ◽

X Ray Diffraction ◽

X Ray ◽

Contact Distance ◽

The Common ◽

Complex Salts ◽

Cell Data ◽

Unit Cell Data ◽

Ir Bands

Of the isostructural series of monoclinic (PNP)[Ln(Pc)2]• xH2O compounds (Ln = La ••• Tm) the crystal structures of the complex salts of tervalent La (1), Gd (2) and Tm (3) have been determined by single crystal X-ray diffraction analysis. Unit cell data for 2: space group P21/c; a = 15.172(8), b = 20.826(2), c = 25.876(3) Å, β = 95.19(3)°, V - 8143(4) Å3, Z = 4; 1 and 3 are isostructural with 2. The lanthanide ion occupies the center of a nearly ideal square antiprism, although the two staggered phthalocyanine rings are severely distorted in an unsymmetrical funnel-shaped fashion due to electronic, steric, and packing influences in the crystal lattice. Steric effects dictate also the geometry of the PNP cation, which adopts a hybrid conformation whose structural characteristics are between the common linear and bent conformers with medium short P-N distances (1.562 Å) and large P-N-P angles in the range 165.6° (1) > 158.3° (2) > 156.1° (3). The strong IR bands at ca. 1375 cm-1 assigned to the asym. (P-N) stretch are diagnostic for this hybrid conformation. The presence of water of crystallization in the periphery of the diphthalocyanine anion is confirmed. The shortest contact distance is observed to one of the bridging nitrogen atoms of the Pc2- ligand (3.02 Å) indicating a weak (HO-H•••N) hydrogen bond

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The Influence of HEMC on Cement and Cement-Lime Composites Setting Processes

Materials ◽

10.3390/ma13245814 ◽

2020 ◽

Vol 13 (24) ◽

pp. 5814

Author(s):

Edyta Spychał ◽

Przemysław Czapik

Keyword(s):

Ultrasonic Method ◽

Methyl Cellulose ◽

Diffraction Method ◽

Hydrated Lime ◽

Hydration Reaction ◽

X Ray Diffraction ◽

X Ray ◽

Calorimetric Measurements ◽

Setting Process ◽

Viscosity Modifying Admixture

In this article, the effect of hydroxyethyl methyl cellulose (HEMC), which is a polymeric viscosity modifying admixture on the mineral based composites setting processes, was studied. Previous studies available in the literature included the evaluation of the influence of this admixture on the hydration processes of cement or lime pastes. In this paper, the analysis of this issue was extended to include cement-lime composites. The composition of the pastes and mortars differed in the type of binder (the tests were carried out on cement-based and cement-lime-based materials, in which the cement was replaced in 50% with hydrated lime), as well as the amount and viscosity of the admixture. The study of mortars setting processes and hardening processes using the ultrasonic method was supplemented in the work with calorimetric measurements and phases analysis by the X-ray diffraction method. Finally, it was found that the HEMC reduces the rate of a hydration reaction in cement and cement-lime pastes. The amount of admixture used has a greater influence on the changes taking place during the setting process than the admixture viscosity or the type of binder.

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Simple New Method for the Preparation of La(IO3)3 Nanoparticles

Nanomaterials ◽

10.3390/nano10122400 ◽

2020 ◽

Vol 10 (12) ◽

pp. 2400 ◽

Cited By ~ 1

Author(s):

Zoulikha Hebboul ◽

Amira Ghozlane ◽

Robin Turnbull ◽

Ali Benghia ◽

Sara Allaoui ◽

...

Keyword(s):

Single Phase ◽

New Method ◽

X Ray Diffraction ◽

Chemical Route ◽

X Ray ◽

The Common ◽

Controlled Preparation ◽

Iodate Ions ◽

Scanning Electron ◽

Soft Chemical Route

We present a cost- and time-efficient method for the controlled preparation of single phase La(IO3)3 nanoparticles via a simple soft-chemical route, which takes a matter of hours, thereby providing an alternative to the common hydrothermal method, which takes days. Nanoparticles of pure α-La(IO3)3 and pure δ-La(IO3)3 were synthesised via the new method depending on the source of iodate ions, thereby demonstrating the versatility of the synthesis route. The crystal structure, nanoparticle size-dispersal, and chemical composition were characterised via angle- and energy-dispersive powder X-ray diffraction, scanning electron microscopy, and Fourier-transform infrared spectroscopy.

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Incorporation of AlCl3 and As2O3 in Composite Cement Systems

MRS Proceedings ◽

10.1557/proc-807-353 ◽

2003 ◽

Vol 807 ◽

Author(s):

J Hill ◽

J H Sharp

Keyword(s):

Aluminium Chloride ◽

X Ray Diffraction ◽

Early Hydration ◽

X Ray ◽

Friedel’S Salt ◽

Fuel Ash ◽

Blastfurnace Slag ◽

Addition Level ◽

Cementitious Systems ◽

Composite Cements

ABSTRACTAs part of an investigation into the consequences of adding inorganic metal salts to composite cements, based on blastfurnace slag (BFS) and pulverised fuel ash (PFA), the effect on the hydration behaviour of adding AlCl3 or As2O3 to the mix water of a number of cementitious systems was investigated using isothermal conduction calorimetry (ICC) and x-ray diffraction (XRD). Four cement systems were investigated; ordinary Portland cement (OPC), 3:1 BFS: OPC, 9:1 BFS:OPC and 3:1 PFA:OPC. AlCl3·7H2O and As2O3 were added to the mix water at 0.1% and 1% concentrations. Results from ICC indicated that the addition of As2O3 had very little effect on the setting and early hydration of any of the cements. AlCl3, however, inhibited the setting of the composite cements at the 1% addition level but accelerated the OPC at 0.1%. The expected hydration products were observed, with the additional observation of Friedel's salt in the presence of aluminium chloride additions and vaterite in both the aluminium and arsenic-containing systems after 180 days hydration.

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Carbide slag–activated ground granulated blastfurnace slag for soft clay stabilization

Canadian Geotechnical Journal ◽

10.1139/cgj-2014-0007 ◽

2015 ◽

Vol 52 (5) ◽

pp. 656-663 ◽

Cited By ~ 20

Author(s):

Yaolin Yi ◽

Liyang Gu ◽

Songyu Liu ◽

Anand J. Puppala

Keyword(s):

Mercury Intrusion Porosimetry ◽

Soft Clay ◽

X Ray Diffraction ◽

X Ray ◽

Mercury Intrusion ◽

Carbide Slag ◽

Calcium Silicate Hydrates ◽

Blastfurnace Slag ◽

Ucs Test ◽

Curing Age

This study addresses the use of an industry by-product, carbide slag (CS), to activate another industry by-product, ground granulated blastfurnace slag (GGBS), for soft clay stabilization in comparison to Portland cement (PC). The properties of CS–GGBS stabilized clays were investigated through unconfined compressive strength (UCS) test, mercury intrusion porosimetry (MIP), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results indicated that the optimum CS content for the CS–GGBS stabilized clay to yield the highest UCS was 4%–6%, varying slightly with curing age and GGBS content. The UCS of the optimum CS-GGBS stabilized clays was more than twice that of the corresponding PC stabilized clays. The main hydration products detected for the CS–GGBS stabilized clays included calcium silicate hydrates (CSH), calcium aluminate hydrates (CAH), and alumino-ferrite monosulfate (AFm).

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