Carbonating magnesia for soil stabilization

2013 ◽  
Vol 50 (8) ◽  
pp. 899-905 ◽  
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.

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

2016 ◽  
Vol 53 (5) ◽  
pp. 773-782 ◽  
Author(s):  
Yaolin Yi ◽  
Martin Liska ◽  
Fei Jin ◽  
Abir Al-Tabbaa
Keyword(s):  
Reaction Rate ◽  
Soil Stabilization ◽  
Hydrated Lime ◽  
Strength Testing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Blastfurnace Slag ◽  
Stabilized Soil ◽  
The Common ◽  
Reactive Magnesia

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.

Use of rice husk ash to enhance lime treatment of soil

1992 ◽  
Vol 29 (5) ◽  
pp. 843-852 ◽  
Author(s):  
Faisal Haji Ali ◽  
Aminuddin Adnan ◽  
Chew Kam Choy
Keyword(s):  
Rice Husk ◽  
Soil Stabilization ◽  
Rice Husk Ash ◽  
Strength Development ◽  
X Ray Diffraction ◽  
Lime Treatment ◽  
Unconfined Compression Test ◽  
X Ray ◽  
Local Soil ◽  
Mineralogical Study

The paper presents the influences of different mix proportions of lime and rice husk ash (RHA) on compaction, strength properties, and durability characteristics of a local soil to evaluate the effectiveness of using RHA as a pozzolan to enhance the lime treatment of the soil. Mineralogical study was carried out also by using X-ray diffraction techniques to identify the reaction products that are responsible for the modification of the soil properties. In the mineralogical study, samples were analysed at different stages of curing. The results show that addition of RHA enhances not only the strength development but also the durability of the lime stabilized soil. Key words : soil stabilization, Atterberg limits, compaction test, unconfined compression test, X-ray diffraction.

Property changes of reactive magnesia–stabilized soil subjected to forced carbonation

2016 ◽  
Vol 53 (2) ◽  
pp. 314-325 ◽  
Author(s):  
Yaolin Yi ◽  
Kaiwen Lu ◽  
Songyu Liu ◽  
Abir Al-Tabbaa
Keyword(s):  
Specific Gravity ◽  
Moisture Content ◽  
Natural Soil ◽  
Dry Density ◽  
Binding Effect ◽  
Triaxial Cell ◽  
Stabilized Soil ◽  
Mechanical And Microstructural Properties ◽  
Property Changes ◽  
Reactive Magnesia

A reactive magnesia (MgO) was used to stabilize a natural soil; the MgO-stabilized soil was subjected to forced carbonation with pressurized gaseous CO2 in a triaxial cell set-up. The change of physical properties, including bulk density, moisture content, dry density, specific gravity, and porosity, of the stabilized soil during carbonation was studied. The mechanical and microstructural properties of the carbonated MgO-stabilized soil were also investigated through unconfined compressive strength (UCS) test, X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). The results indicated that the carbonation of MgO-stabilized soil consumed CO2 and water, and produced expansive carbonation products; this consequently increased the dry density, and reduced the moisture content, specific gravity, and porosity of the stabilized soil. After being carbonated for only 1.5 h, the MgO-stabilized soil yielded remarkable strength, with UCS higher than that of the 28 day ambient cured Portland cement–stabilized soil, mainly due to the high binding effect of carbonation products and the low porosity of carbonated MgO-stabilized soil. The carbonated MgO-stabilized soil achieved a high degree of carbonation in a few hours (≤12 h), with the maximum CO2/MgO ratio in a range of 0.76–1.07.

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

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

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.

Effect of Varying Wt% of TiC on Mechanical and Wear Properties of RZ5-TiC In-Situ Composite

2018 ◽  
Vol 8 (2) ◽  
pp. 45-56 ◽  
Author(s):  
Deepak Mehra ◽  
M.M. Mahapatra ◽  
S. P. Harsha
Keyword(s):  
Wear Resistance ◽  
Wear Behavior ◽  
Wear Test ◽  
X Ray Diffraction ◽  
Wear Properties ◽  
X Ray ◽  
Tic Particle ◽  
Mechanical And Microstructural Properties ◽  
Sliding Distance

The purpose of this article is to enhance the mechanical properties and wear resistance of the RZ5 alloy used in the aerospace application by adding TiC particles. The present study discusses processing of in-situ RZ5-TiC composite fabricated by self-propagating high temperature (S.H.S.) method and its wear behavior. The effects of TiC particle on mechanical and microstructural properties of the composite are studied. The wear test is performed by varying the sliding distance and applied load. The composite is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results exhibited the properties like strength and hardness of RZ5-10wt%TiC composite has been increased considerably, while grain size is decreased as compared to the RZ5 alloy. The fractography indicated mixed mode (quasi-cleavage and ductile feature) failure of the composites. The wear results showed improvement in wear resistance of the composite. The FESEM showed dominate wear mechanisms are abrasion, ploughing grooves.

Large-scale and facile fabrication of PbSe nanostructures by selenization of a Pb sheet

2015 ◽  
Vol 08 (05) ◽  
pp. 1550063 ◽  
Author(s):  
Sara Hoomi ◽  
Ramin Yousefi ◽  
Farid Jamali-Sheini ◽  
Abdolhossein Sáaedi ◽  
Mohsen Cheraghizade ◽  
...  
Keyword(s):  
Large Scale ◽  
Chemical Vapor ◽  
Infrared Region ◽  
Photoelectron Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Facile Fabrication ◽  
Higher Temperature ◽  
Set Up ◽  
Lower Temperature

PbSe nanostructures were synthesized by selenization of lead sheets in a chemical vapor deposition (CVD) set-up under a selenium ambiance. The lead sheets were placed in the different temperature zones, between 300°C and 450°C. Field emission scanning electron microscope (FESEM) images showed that, PbSe nanostructures grown on the lead sheets with different morphologies. PbSe nanostructures with flakes shape were grown on the lead sheets that were placed in the lower temperature, while PbSe nanocubes and nanorods, which were grown on the nanocubes, were grown on the lead sheets in the higher temperature. The phase and composition of the product were identified by X-ray diffraction (XRD) pattern and X-ray photoelectron spectra (XPS). The XRD and XPS results showed that, the PbSe phase was started to form after 350°C and completed at 450°C. However, the XPS results showed that the Se concentration was different in the samples. In addition, Raman measurements confirmed the XRD and XPS results and indicated three Raman active modes, which belonged to PbSe phase for the nanostructures. The optical properties of the products were characterized by UV–Vis. The optical characterization results showed a band gap for the PbSe nanostructures in the infrared region.

Synthesis and Structural Characterization of Ca14NbxIn1-xAs11 (x ≈ 0.85)

2016 ◽  
Vol 257 ◽  
pp. 147-151 ◽  
Author(s):  
Yi Wang ◽  
Svilen Bobev
Keyword(s):  
Physical Properties ◽  
Side Reaction ◽  
Structure Type ◽  
Major Product ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ongoing Work ◽  
Set Up

Single-crystals of the new compound Ca14NbxIn1–xAs11 have been obtained from a solid-state reaction in a sealed Nb ampoule. The initial experiment had been set up with the aim to investigate the effect of electron doping (via In) on the crystal structure and physical properties of Ca14MnAs11. Subsequent single-crystal X-ray diffraction and elemental analysis work suggested that instead of Ca14MnxIn1–xAs11, the major product of the reaction is the phase Ca14NbxIn1–xAs11. This supposition was corroborated when the title compound was synthesized from a reaction of Ca, In and As in a sealed Nb ampoule, proving that, 1) Mn metal is not included in the structure, and 2) that the inadvertent side reaction of As with the walls of the Nb container is the source of the niobium. The overall structure is isotypic with the tetragonal Ca14AlSb11 structure type (space group I41/acd), although some marked differences between the two must be noted. Current ongoing work is focused on the synthesis of phase pure polycrystalline samples and determination of the physical properties of this unusual transition metal Zintl phase.

scholarly journals High-Throughput Crystallization Pipeline at the Crystallography Core Facility of the Institut Pasteur

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4451 ◽  
Author(s):  
Patrick Weber ◽  
Cédric Pissis ◽  
Rafael Navaza ◽  
Ariel E. Mechaly ◽  
Frederick Saul ◽  
...  
Keyword(s):  
High Throughput ◽  
Sequence Data ◽  
Data Bank ◽  
Whole Genome Sequence ◽  
Whole Genome ◽  
X Ray Diffraction ◽  
Sequencing Technology ◽  
X Ray ◽  
Set Up ◽  
General User

The availability of whole-genome sequence data, made possible by significant advances in DNA sequencing technology, led to the emergence of structural genomics projects in the late 1990s. These projects not only significantly increased the number of 3D structures deposited in the Protein Data Bank in the last two decades, but also influenced present crystallographic strategies by introducing automation and high-throughput approaches in the structure-determination pipeline. Today, dedicated crystallization facilities, many of which are open to the general user community, routinely set up and track thousands of crystallization screening trials per day. Here, we review the current methods for high-throughput crystallization and procedures to obtain crystals suitable for X-ray diffraction studies, and we describe the crystallization pipeline implemented in the medium-scale crystallography platform at the Institut Pasteur (Paris) as an example.

Shock Wave Compression of NaCl Single Crystals observed by Flash-X-Ray Diffraction

1978 ◽  
Vol 33 (8) ◽  
pp. 918-923 ◽  
Author(s):  
F. Müller ◽  
E. Schulte
Keyword(s):  
Shock Wave ◽  
Single Crystals ◽  
Observation Time ◽  
Plane Shock ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wave Compression ◽  
Shock Wave Compression ◽  
Diffraction Patterns ◽  
Set Up

Flash-x-ray-diffraction patterns (FXD) with an exposure time of 4 ns of NaCl single crystals compressed by plane shock waves are obtained at pressures of about 30 kbar. From the diffraction patterns the compression is determined and compared with Hugoniot data. During shock load the lattice shows an uniaxial compression. While in case of measurements at the free surface an observation time of only a few nanoseconds is available, this experimental set-up allows an observation time of two microseconds.

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