Study on Crack Development and Micro-Pore Mechanism of Expansive Soil Improved by Coal Gangue under Drying–Wetting Cycles

Expansive soil is prone to cracks under a drying–wetting cycle environment, which brings many disasters to road engineering. The main purpose of this study is use coal gangue powder to improve expansive soil, in order to reduce its cracks and further explore its micro-pore mechanism. The drying–wetting cycles test is carried out on the soil sample, and the crack parameters of the soil sample are obtained by Matlab and Image J software. The roughness and micro-pore characteristics of the soil samples are revealed by means of the Laser confocal 3D microscope and Mercury intrusion meter. The results show that coal gangue powder reduces the crack area ratio of expansive soil by 48.9%, and the crack initiation time is delayed by at least 60 min. Coal gangue powder can increase the internal roughness of expansive soil. The greater the roughness of the soil, the less cracks in the soil. After six drying–wetting cycles, the porosity and average pore diameter of the improved and expanded soil are reduced by 37% and 30%, respectively, as compared to the plain expansive soil. By analyzing the cumulative pore volume and cumulative pore density parameters of soil samples, it is found that the macro-cracks are caused by the continuous connection and fusion of micro-voids in soil. Coal gangue powder can significantly reduce the proportion of micro-voids, cumulative pore volume, and cumulative pore density in expansive soil, so as to reduce the macro-cracks.

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Fuels Desulphurisation by Adsorbtion on Fe / Bentonite

Revista de Chimie ◽

10.37358/rc.17.3.5483 ◽

2017 ◽

Vol 68 (3) ◽

pp. 483-486

Author(s):

Constantin Sorin Ion ◽

Mihaela Bombos ◽

Gabriel Vasilievici ◽

Dorin Bombos

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Pore Volume ◽

Pore Diameter ◽

Adsorption Process ◽

Continuous System ◽

Gas Oil ◽

Average Pore ◽

Atmospheric Distillation

Desulfurisation of atmospheric distillation gasoline and gas oil was performed by adsorption process on Fe/ bentonite. The adsorbent was characterized by determining the adsorption isotherms, specific surface area, pore volume and average pore diameter. Adsorption experiments of atmospheric distillation gasoline and gas oil were performed in continuous system at 280�320oC, 5 atm and volume hourly space velocities of 1�2 h-1. The efficiency of adsorption on Fe / bentonite was better at desulphurisation of gasoline versus gas oil.

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Fabrication of Low Cost Membrane from Anodic Aluminum Oxide

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.751.363 ◽

2017 ◽

Vol 751 ◽

pp. 363-367

Author(s):

Peerawith Sumtong ◽

Apiluck Eiad-Ua

Keyword(s):

Aluminum Oxide ◽

Anodic Aluminum Oxide ◽

Pore Diameter ◽

Average Pore Diameter ◽

Process Conditions ◽

Low Grade ◽

Pore Density ◽

Average Pore ◽

Anodic Aluminum ◽

Interpore Distance

Anodic Aluminum Oxide (AAO) membrane has been successfully fabricated from two-step anodization with aluminum low grade (Al6061). The pore density, the pore diameter, and the interpore distance can be controlled by varying anodization process conditions. However, there are limits to control the mechanical strength and growth of AAO arrays, such as pore density, pore diameter and interpore distance. In this research the self-organized two-step anodization is carried out varying time at 24, 48 and 72 hours, respectively with 40V at the low temperature 2-5°C. The optimum conditions of AAO with two-step anodization is 40V for 48 hr. Finally, AAO substrate is separated from aluminum low-grade and enlarged pore diameter with pore widening process by 5% H3PO4. The physical properties were investigated by mean of field emission scanning electron microscope (FE-SEM) show that the average pore diameter and average interpore distance increase with the anodization time. Al6061 Aluminum substrate can be used to fabricate a nanoporous AAO film with an average pore diameter and average interpore distance larger than 70 and 90 nanometers, respectively but less mechanical stability.

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Relationship between the Shear Strength and Microscopic Pore Parameters of Saline Soil with Different Freeze-Thaw Cycles and Salinities

Symmetry ◽

10.3390/sym12101709 ◽

2020 ◽

Vol 12 (10) ◽

pp. 1709

Author(s):

Jiaqi Wang ◽

Qing Wang ◽

Sen Lin ◽

Yan Han ◽

Shukai Cheng ◽

...

Keyword(s):

Shear Strength ◽

Pore Structure ◽

Pore Diameter ◽

Saline Soil ◽

Soil Samples ◽

Average Pore Diameter ◽

Failure Strength ◽

Average Pore ◽

Freeze Thaw ◽

The Relationship

Saline soil is a widely distributed special soil with poor engineering properties. In seasonally frozen regions, the poor properties of saline soil will cause many types of engineering damage such as road boiling, melt sinking, and subgrade instability. These engineering failures are closely related to the shear strength of saline soil. However, there are relatively few studies on saline soil in cold regions. The strength of the soil is always determined by its microstructure; therefore, the study aims to investigate the relationship between the shear strength and microscopic pore structure of saline soil with different freeze–thaw cycles and salinities. The shear strength characteristics of saline soil with different salinities subjected to different freeze–thaw cycles were obtained by triaxial tests. In addition, the microstructure of the soil samples was investigated by scanning electron microscopy (SEM) tests, and the microscopic pore parameters of the soil samples, including porosity (N), average pore diameter (D¯), average shape coefficient (K), surface fluctuation fractal dimension (F), and orienting probability entropy (Hm), were obtained by image processing software quantitatively. Based on the experimental results, the influence of freeze–thaw cycles and salinity on the shear strength characteristics and microstructure of the soil samples were analyzed. Besides that, in order to effectively eliminate the collinearity between independent variables and obtain a stable and reasonable regression model, principal component regression (PCR) analysis was adopted to establish the relationship between the microscopic pore parameters and the failure strength of the soil samples. The fitting results demonstrated that the failure strength of saline soil is mainly related to the size and direction of the pores in the soil, and it has little correlation with pore shape. The failure strength of the soil was negatively correlated with the average pore diameter (D¯) and porosity (N), and it was positively correlated with the orienting probability entropy of the pores (Hm). This study may provide a quantitative basis for explaining the variation mechanism of the mechanical properties of saline soil from a microscopic perspective and provide references for the symmetry between the changes of the macroscopic properties and microscopic pore structure of the saline soil in cold regions.

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Surfactant-Templated Synthesis of Modified Porous Clay Heterostructure (PCH)

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.55-57.317 ◽

2008 ◽

Vol 55-57 ◽

pp. 317-320 ◽

Cited By ~ 3

Author(s):

K. Srithammaraj ◽

Rathanawan Magaraphan ◽

H. Manuspiya

Keyword(s):

Pore Volume ◽

Pore Diameter ◽

Condensation Reaction ◽

High Surface ◽

High Surface Area ◽

Bentonite Clay ◽

Directed Assembly ◽

Average Pore Diameter ◽

Average Pore ◽

Surface Areas

Porous Clay Heterostructures (PCHs) have been prepared by the surfactant-directed assembly of mesostructured silica within the two-dimensional interlayer galleries of clays. The PCH is an interesting material to use as entrapping system such as ethylene scavenger, owing to its high surface area with uniform and specific pore size. In the present work, the PCH was synthesized within the galleries of Na-bentonite clay by the polymerization of tetraethoxysilane (TEOS) in the presence of surfactant micelles. In addition, a mesoporous clay with organic-inorganic hybrid (HPCH) is modified via co-condensation reaction of TEOS with methyltriethoxysilane (MTS) to enhance hydrophobicity of PCH material for entrapping system. According to pore characterization, PCHs have surface areas of 421-551 m2/g, an average pore diameter in the supermicropore to small mesopore range of 4.79-5.02 nm, and a pore volume of 0.57-0.66 cc/g while HPCHs have surface areas of 533-966 m2/g, an average pore diameter of 4.28-6.38 nm, and a pore volume of 0.42-0.77cc/g.

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Experimental Research on the Preparation of Porous Activated Carbon from Orange Wastes

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.79-82.1907 ◽

2009 ◽

Vol 79-82 ◽

pp. 1907-1910

Author(s):

Zhi Gang Xie

Keyword(s):

Activated Carbon ◽

Surface Area ◽

Pore Volume ◽

Pore Diameter ◽

Total Pore Volume ◽

Carbonization Temperature ◽

Bet Surface Area ◽

Average Pore ◽

Impregnation Ratio ◽

Heat Preservation

Porous activated carbon was prepared from orange wastes using zinc chloride as an activating agent by one-step carbonization method. Effects of impregnation ratio, carbonization temperature and heat preservation time on pore characteristics of activated carbon were studied. The porous structures of the orange wastes activated carbon were investigated by BET, D-R equations, BJH equations and Kelvin theory. The morphology was observed using transmission electron microscopy (TEM). The mesoporous activated carbon is gained when the impregnation ratio is 3:1; the carbonization temperature is 550°Cand heat preservation time is 1.0 h. The activated carbon has total pore volume 2.098 cm3/g, mesoporous pore volume 1.438 cm3/g, with a high BET surface area 1476m2/g. The pore distribution of the mesoporous activated carbon is very concentrative, with average pore diameter of 3.88nm. While, the high specific surface area activated carbon is gained when the impregnation ratio is 2:1; the carbonization temperature is 550°Cand heat preservation time is 1.0 h. The activated carbon has high BET surface area 1909 m2/g, while the total pore volume is only 1.448cm3/g and microporous pore volume is 0.889cm3/g, with average pore diameter of 2.29 nm.

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Possibilities of Graphitization of Unburned Carbon from Coal Fly Ash

Minerals ◽

10.3390/min11091027 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1027

Author(s):

Zdzisław Adamczyk ◽

Joanna Komorek ◽

Barbara Białecka ◽

Joanna Całus-Moszko ◽

Agnieszka Klupa

Keyword(s):

Fly Ash ◽

Pore Volume ◽

Pore Diameter ◽

Coal Fly Ash ◽

Total Pore Volume ◽

Starting Material ◽

Unburned Carbon ◽

Active Carbons ◽

Average Pore ◽

Graphite Phase

The paper presents the characteristics of products annealing at the temperatures of 2400 and 3000 °C of unburned carbon from coal fly ash in terms of its possible use as a starting material in the graphitization process. An amorphous substance (organic substance) with an admixture of some minerals has been found in samples subjected to graphitization. However, the graphite phase is dominant in products subjected to graphitization. Studies have also shown a diverse grain morphology in individual samples. The presence of plate-shaped and tube-shaped grains was found. As the graphitization temperature of the starting material increases (2400 and 3000 °C), the specific surface area in the graphitization products decreases. The total pore volume in the samples after the graphitization process was significantly lower than the pore volume of active carbons produced from other unburned carbon. Average pore diameter is similar to the pore diameter in active carbons. The reflectance value of the matrix for the sample graphitized at 3000 °C is characteristic for graphite. Unburned carbon from Polish fly ash can be used as the starting material for graphitization.

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Hydrodesulphurization of Thiophenes over CoMoRe/ ZSM 5gama-Al2O3 Catalyst

Revista de Chimie ◽

10.37358/rc.18.6.6330 ◽

2018 ◽

Vol 69 (6) ◽

pp. 1386-1390

Author(s):

Rami Doukeh ◽

Mihaela Bombos ◽

Marioara Moldovan ◽

Ion Bolocan

Keyword(s):

Pore Volume ◽

Pore Diameter ◽

Fixed Bed ◽

Texture Features ◽

Molar Ratio ◽

Catalytic Reactor ◽

Average Pore ◽

Metallic Catalyst ◽

C 30 ◽

Al2o3 Catalyst

The hydrodesulphurization (HDS) of thiophenes was performed on metallic catalyst CoMoRe/ZSM5-gAl2O3. Experiments were carried out on a fixed bed catalytic reactor at 175-300�C, 30-60 atm, thiophene volume hourly space velocities of 1h-1- 4h-1 and molar ratio hydrogen/thiophene of 60/1. Texture features like specific surface area, the pore volume and the average pore diameter decrease after catalyst sulfurization. The thiophenes conversion on CoMoRe/gAl2O3-Zn-HZSM 5 catalyst differs with the nature of the studied thiophenes.

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Effects of AKD Sizing on the Morphology and Pore Distribution Properties of OCC Fibers

Journal of Nanomaterials ◽

10.1155/2019/9490602 ◽

2019 ◽

Vol 2019 ◽

pp. 1-6

Author(s):

Hua Chen ◽

Jing Yang ◽

Zhijun Hu ◽

Bingbing Zheng ◽

Jun Sun ◽

...

Keyword(s):

Pore Volume ◽

Pore Diameter ◽

Control Sample ◽

Bet Surface Area ◽

Alkyl Ketene Dimer ◽

Average Pore ◽

Force Microscopy ◽

Atomic Force ◽

Dispersed Particles ◽

Scanning Electron

Changes of the morphology and pore structure of old corrugated container (OCC) fibers during an alkyl ketene dimer (AKD) sizing process were studied. The resulting samples were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle, and BET surface area analysis. The length of fibers had obvious influence on the AKD sizing effect, and the length of fibers ranged from 100 to 200 meshes showed the best sizing performance. The surface roughness of 0.3% AKD sizing OCC fibers decreased from 27.949 nm to 12.811 nm. Compared with the control sample, the pore volume of fibers sized with 0.1% AKD decreased 4.3% when the average pore diameter was fixed at 2.4~3.0 nm. And when the usage of AKD increased to 0.3% and 0.5%, the pore volume decreased 1.4% and 6.3% accordingly. The decrease in the pore volume of AKD-sized fiber indicated the penetration and deposition of dispersed particles of AKD in the fiber lumens.

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Effects of Erosion Form and Admixture on Cement Mortar Performances Exposed to Sulfate Environment

Crystals ◽

10.3390/cryst10090774 ◽

2020 ◽

Vol 10 (9) ◽

pp. 774

Author(s):

Peng Liu ◽

Ying Chen ◽

Zhiwu Yu

Keyword(s):

Mechanical Properties ◽

Fly Ash ◽

Pore Diameter ◽

Energy Dispersive Spectrometer ◽

Sulfate Solution ◽

Crystal Form ◽

High Concentration ◽

Pore Characteristics ◽

Average Pore ◽

Before And After

The effects of the admixtures, erosion age, concentration of sulfate solution, and erosion form of sulfate attack on the mechanical properties of mortar were investigated. Simultaneously, the microstructure, pore characteristics, kinds and morphologies of erosion products of mortar before and after sulfate attacks were performed by Mercury Intrusion Porosimetry (MIP), Environment Scanning Electronic Microscope and Energy Dispersive Spectrometer (ESEM-EDS). In addition, the crystal form and morphology characteristics of crystallization on mortar surfaces attacked by partial immersion form were studied. The results showed that the compressive and flexural strengths of mortar attacked by sulfate for four months decreased with the increase of the replacement of cement with fly ash, and the corresponding strength of mortar containing slag first increased and then decreased. The admixtures can improve the microstructure and mechanical properties of mortar within the replacement ratio of 10%. Although the change laws of the mortar specimens containing different admixtures were similar, the mortar containing slag had an excellent sulfate resistance under the same condition. Compared with the complete immersion form, the strength variation of the mortar containing fly ash attacked by semi-immersion form was less. The porosity and average pore diameter of mortar attacked by sulfate for four months increased, and the percentage of micropore with the pore diameter less than 200 nm increased. Plenty of rod-like and plate-like erosion products were generated in mortar attacked by a sulfate solution with a high concentration. A larger number of fibrous and flocculent crystallization covered the mortar’s surface containing fly ash, but it was a granular and dense crystallization formed on the mortar’s surface containing slag. Much dendritic erosion product was generated in the mortar attacked by semi-immersion form, and ESEM-EDS analysis revealed that it may be scawtite, spurrite, and residue of the decomposed calcium silicate hydrate (CSH) in the inner mortar; however, the crystallization sodium sulfate was crystallized on mortar surface.

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Kinetics of 1-dodecanethiol Desulfurization by Reactive Adsorbtion on MgO/dolomite

Revista de Chimie ◽

10.37358/rc.18.12.6765 ◽

2019 ◽

Vol 69 (12) ◽

pp. 3439-3444

Author(s):

Constantin Sorin Ion ◽

Mihaela Bombos ◽

Rami Doukeh ◽

Gabriel Vasilievici ◽

Vasile Matei

Keyword(s):

Magnesium Oxide ◽

Pore Volume ◽

Pore Diameter ◽

Adsorption Process ◽

Continuous System ◽

Average Pore ◽

Reactive Adsorption ◽

Desulfurization Process ◽

Increasing Temperature ◽

Kinetics Of

Desulfurisation of 1-dodecanethiol was performed by adsorption process on MgO adsorbent. The adsorbant was characterized by determining the adsorption isotherms, specific surface area, pore volume and average pore diameter. Adsorption experiments were performed in continuous system at 300-450�C, 5 atm and volume hourly space velocities of 1�2 h-1. Conversion of 1-dodecanetol increases with increasing temperature and decreasing volume hourly space velocities. It was identified the stage determinant of the process and a kinetic study of the desulfurization process was developed by reactive adsorption of 1-dodecanethiol on a magnesium oxide adsorbent.

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