Clays are not created equal – effects of clay mineral type on soil hydraulic and mechanical properties

<p>Clay minerals dominate the soil colloidal fraction and often carry the largest specific surface area &#8211; a property that controls various soil hydraulic and mechanical properties (SHMPs; e.g. water retention, permeability, and internal friction). Differences in microscale structure among clay mineral types in tropical and temperate regions affect the specific surface area and result in higher permeability and internal friction angle values for tropical soils with inactive kaolinite clay minerals. Presently, the soil clay size fraction used to parameterize SHMPs with pedotransfer functions (PTFs) ignores clay mineral type, leading to inconsistent parameter representation. In this study, we present new PTFs informed by clay minerals, enabling enhanced estimation of friction angle and saturated hydraulic conductivity. To capture higher conductivity and lower air entry values in tropical soils, we developed a hierarchical packing model and validated this new PTF approach using literature data from various tropical regions. We leveraged recent global maps of clay minerals to demonstrate that a strong climatic and spatial segregation of active and inactive clays enable spatially resolved consideration of clay mineral type in SHMP estimation. We applied these clay-informed PTFs to improve SHMP representation regionally with implications for a wide range of hydrological and geomechanical Earth surface processes.</p>

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Effects of Hydraulic Gradient and Clay Type on Permeability of Clay Mineral Materials

Minerals ◽

10.3390/min10121064 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1064

Author(s):

Masanori Kohno

Keyword(s):

Hydraulic Conductivity ◽

Specific Surface ◽

Surface Area ◽

Clay Mineral ◽

Specific Surface Area ◽

Hydraulic Gradient ◽

Consistency Index ◽

Hydrogen Energy ◽

The Difference ◽

Mineral Type

Considering the relevance of clay mineral-bearing geomaterials in landslide/mass movement hazard assessment, various engineering projects for resource development, and stability evaluation of underground space utilization, it is important to understand the permeability of these clay mineral-based geomaterials. However, only a few quantitative data have been reported to date regarding the effects of the clay mineral type and hydraulic gradient on the permeability of clay mineral materials. This study was conducted to investigate the permeability of clay mineral materials based on the clay mineral type, under different hydraulic gradient conditions, through a constant-pressure permeability test. Comparative tests have revealed that the difference in the types of clay mineral influences the swelling pressure and hydraulic conductivity. In addition, it has been found that the difference in water pressure (hydraulic gradient) affects the hydraulic conductivity of clay mineral materials. The hydraulic conductivity has been found to be closely associated with the specific surface area of the clay mineral material. Furthermore, the hydraulic conductivity value measured is almost consistent with the value calculated theoretically using the Kozeny–Carman equation. Moreover, the hydraulic conductivity is also found to be closely associated with the hydrogen energy, calculated from the consistency index of clay. This result suggests that the hydraulic conductivity of clay mineral materials can be estimated based on the specific surface area and void ratio, or consistency index of clay.

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Porosity model and pore evolution of transitional shales: an example from the Southern North China Basin

Petroleum Science ◽

10.1007/s12182-020-00481-7 ◽

2020 ◽

Vol 17 (6) ◽

pp. 1512-1526

Author(s):

Xiao-Guang Yang ◽

Shao-Bin Guo

Keyword(s):

Specific Surface ◽

Surface Area ◽

Clay Minerals ◽

Clay Mineral ◽

Specific Surface Area ◽

Mineral Content ◽

High Specific Surface Area ◽

High Porosity ◽

Mechanical Compaction ◽

Pore Evolution

AbstractThe evolution of shale reservoirs is mainly related to two functions: mechanical compaction controlled by ground stress and chemical compaction controlled by thermal effect. Thermal simulation experiments were conducted to simulate the chemical compaction of marine-continental transitional shale, and X-ray diffraction (XRD), CO2 adsorption, N2 adsorption and high-pressure mercury injection (MIP) were then used to characterize shale diagenesis and porosity. Moreover, simulations of mechanical compaction adhering to mathematical models were performed, and a shale compaction model was proposed considering clay content and kaolinite proportions. The advantage of this model is that the change in shale compressibility, which is caused by the transformation of clay minerals during thermal evolution, may be considered. The combination of the thermal simulation and compaction model may depict the interactions between chemical and mechanical compaction. Such interactions may then express the pore evolution of shale in actual conditions of formation. Accordingly, the obtained results demonstrated that shales having low kaolinite possess higher porosity at the same burial depth and clay mineral content, proving that other clay minerals such as illite–smectite mixed layers (I/S) and illite are conducive to the development of pores. Shales possessing a high clay mineral content have a higher porosity in shallow layers (< 3500 m) and a lower porosity in deep layers (> 3500 m). Both the amount and location of the increase in porosity differ at different geothermal gradients. High geothermal gradients favor the preservation of high porosity in shale at an appropriate Ro. The pore evolution of the marine-continental transitional shale is divided into five stages. Stage 2 possesses an Ro of 1.0%–1.6% and has high porosity along with a high specific surface area. Stage 3 has an Ro of 1.6%–2.0% and contains a higher porosity with a low specific surface area. Finally, Stage 4 has an Ro of 2.0%–2.9% with a low porosity and high specific surface area.

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Effects of clay type on soil hydraulic and mechanical properties - a global perspective

10.5194/egusphere-egu2020-8471 ◽

2020 ◽

Author(s):

Peter Lehmann ◽

Ben Leshchinsky ◽

Ben Mirus ◽

Ning Lu ◽

Surya Gupta ◽

...

Keyword(s):

Mechanical Properties ◽

Hydraulic Conductivity ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Clay Fraction ◽

Friction Angle ◽

Soil Hydraulic ◽

The Tropics ◽

Clay Type

<p>Clay fraction affects soil hydraulic and mechanical properties and dominates specific surface area. Clay fraction is used for soil classification and in pedotransfer functions (PTFs) to estimate soil hydraulic functions from simpler soil properties (texture). Remarkably, despite large variations in composition and properties of clay minerals, PTFs use this attribute in undifferentiated manner, applied similarly to soils in the tropics dominated by Kaolinite and temperate soils with Montmorillonite. The large specific surface area of Montmorillonite compared to Kaolinite reduces both the soil hydraulic conductivity and the residual friction angle. We develop PTFs informed by clay-type via soil specific surface area effects on saturated hydraulic conductivity and residual friction angle. For friction angle, PTFs were fitted to experimental data using information on clay content and clay type. For hydraulic conductivity, analytical models based on surface area and particle size were adapted to capture conductivity data from different climatic regions. Global distributions of clay types are used to map soil specific surface area and related hydro-mechanical properties to improve land-surface models (especially in the tropics) and refine natural hazard risk assessment (landslides and debris flows).</p>

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Nanoporous Quasi-High-Entropy Alloy Microspheres

Metals ◽

10.3390/met9030345 ◽

2019 ◽

Vol 9 (3) ◽

pp. 345 ◽

Cited By ~ 3

Author(s):

Lianzan Yang ◽

Yongyan Li ◽

Zhifeng Wang ◽

Weimin Zhao ◽

Chunling Qin

Keyword(s):

Mechanical Properties ◽

Solid Solution ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

High Specific Surface Area ◽

High Entropy Alloy ◽

Face Centered Cubic ◽

High Entropy ◽

Hierarchical Porous

High-entropy alloys (HEAs) present excellent mechanical properties. However, the exploitation of chemical properties of HEAs is far less than that of mechanical properties, which is mainly limited by the low specific surface area of HEAs synthesized by traditional methods. Thus, it is vital to develop new routes to fabricate HEAs with novel three-dimensional structures and a high specific surface area. Herein, we develop a facile approach to fabricate nanoporous noble metal quasi-HEA microspheres by melt-spinning and dealloying. The as-obtained nanoporous Cu30Au23Pt22Pd25 quasi-HEA microspheres present a hierarchical porous structure with a high specific surface area of 69.5 m2/g and a multiphase approximatively componential solid solution characteristic with a broad single-group face-centered cubic XRD pattern, which is different from the traditional single-phase or two-phase solid solution HEAs. To differentiate, these are named quasi-HEAs. The synthetic strategy proposed in this paper opens the door for the synthesis of porous quasi-HEAs related materials, and is expected to promote further applications of quasi-HEAs in various chemical fields.

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Effect of Secondary Carbon Nanofillers on the Electrical, Thermal, and Mechanical Properties of Conductive Hybrid Composites Based on Epoxy Resin and Graphite

Materials ◽

10.3390/ma14154169 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4169

Author(s):

Marcel Zambrzycki ◽

Krystian Sokolowski ◽

Maciej Gubernat ◽

Aneta Fraczek-Szczypta

Keyword(s):

Mechanical Properties ◽

Specific Surface ◽

Epoxy Resin ◽

Surface Area ◽

Specific Surface Area ◽

Hybrid Composites ◽

Department Of Energy ◽

Carbon Nanofillers ◽

The Impact ◽

Secondary Carbon

In this work, we present a comparative study of the impact of secondary carbon nanofillers on the electrical and thermal conductivity, thermal stability, and mechanical properties of hybrid conductive polymer composites (CPC) based on high loadings of synthetic graphite and epoxy resin. Two different carbon nanofillers were chosen for the investigation—low-cost multi-layered graphene nanoplatelets (GN) and carbon black (CB), which were aimed at improving the overall performance of composites. The samples were obtained by a simple, inexpensive, and effective compression molding technique, and were investigated by the means of, i.a., scanning electron microscopy, Raman spectroscopy, electrical conductivity measurements, laser flash analysis, and thermogravimetry. The tests performed revealed that, due to the exceptional electronic transport properties of GN, its relatively low specific surface area, good aspect ratio, and nanometric sizes of particles, a notable improvement in the overall characteristics of the composites (best results for 4 wt % of GN; σ = 266.7 S cm−1; λ = 40.6 W mK−1; fl. strength = 40.1 MPa). In turn, the addition of CB resulted in a limited improvement in mechanical properties, and a deterioration in electrical and thermal properties, mainly due to the too high specific surface area of this nanofiller. The results obtained were compared with US Department of Energy recommendations regarding properties of materials for bipolar plates in fuel cells. As shown, the materials developed significantly exceed the recommended values of the majority of the most important parameters, indicating high potential application of the composites obtained.

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The Effects of Silica-Based Fillers on the Properties of Epoxy Molding Compounds

Materials ◽

10.3390/ma12111811 ◽

2019 ◽

Vol 12 (11) ◽

pp. 1811 ◽

Cited By ~ 6

Author(s):

Mitja Linec ◽

Branka Mušič

Keyword(s):

Mechanical Properties ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Fused Silica ◽

Spiral Flow ◽

Scanning Calorimetry ◽

Molding Compounds ◽

Material Development ◽

The Impact

Global design and manufacturing of the materials with superb properties remain one of the greatest challenges on the market. The future progress is orientated towards researches into the material development for the production of composites of better mechanical properties to the existing materials. In the field of advanced composites, epoxy molding compounds (EMCs) have attained dominance among the common materials due to their excellent properties that can be altered by adding different fillers. One of the main fillers is often based on silicon dioxide (SiO2). The concept of this study was to evaluate the effects of the selected silica-based fillers on the thermal, rheological, and mechanical properties of EMCs. Various types of fillers with SiO2, including crystalline silica and fused silica, were experimentally studied to clarify the impact of filler on final product. Fillers with different shape (scanning electron microscope, SEM), along with different specific surface area (specific surface area analyzer, BET method) and different chemical structure, were tested to explore their modifications on the EMCs. The influence of the fillers on the compound materials was determined with the spiral flow length (spiral flow test, EMMI), glass transition temperature (differential scanning calorimetry, DSC), and the viscosity (Torque Rheometer) of the composites.

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Influence of Zinc Oxide Nanograins on Properties of Epoxidized Natural Rubber Vulcanizates

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.748.79 ◽

2017 ◽

Vol 748 ◽

pp. 79-83 ◽

Cited By ~ 1

Author(s):

Rudeerat Suntako

Keyword(s):

Mechanical Properties ◽

Zinc Oxide ◽

Natural Rubber ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Epoxidized Natural Rubber ◽

Precipitation Method ◽

Cure Characteristics ◽

Permanent Set

Zinc oxide (ZnO) nanograins are synthesized by precipitation method filled epoxidized natural rubber compared to conventional ZnO. The synthesized ZnO nanograins are characterized by X-ray diffraction and transmission electron microscopy and found that average primary size of ZnO synthesized around 40 nm and the specific surface area of 28.72 m2 g-1. Furthermore, the cure characteristics, rubber mechanical properties and permanent set were investigated. The obtained results are found that the ZnO nanograins significantly affected to cure characteristics, rubber mechanical properties and permanent set. This is due to small grain size and large specific surface area.

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Soil moisture adsorption capacity and specific surface area in relation to water vapor pressure in arid and tropical soils

EURASIAN JOURNAL OF SOIL SCIENCE (EJSS) ◽

10.18393/ejss.580889 ◽

2019 ◽

Vol 8 (4) ◽

pp. 289-297

Author(s):

Abdelmonem Mohamed Amer

Keyword(s):

Soil Moisture ◽

Water Vapor ◽

Vapor Pressure ◽

Specific Surface ◽

Adsorption Capacity ◽

Surface Area ◽

Specific Surface Area ◽

Water Vapor Pressure ◽

Tropical Soils ◽

Moisture Adsorption

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COMPARISON OF PORE FRACTAL CHARACTERISTICS BETWEEN MARINE AND CONTINENTAL SHALES

Fractals ◽

10.1142/s0218348x18400169 ◽

2018 ◽

Vol 26 (02) ◽

pp. 1840016 ◽

Cited By ~ 12

Author(s):

JUN LIU ◽

YANBIN YAO ◽

DAMENG LIU ◽

YIDONG CAI ◽

JIANCHAO CAI

Keyword(s):

Specific Surface ◽

Surface Area ◽

Clay Minerals ◽

Specific Surface Area ◽

Pore Diameter ◽

Fractal Dimensions ◽

Average Pore Diameter ◽

Average Pore ◽

Dimension Formula ◽

Marine Shale

Fractal characterization offers a quantitative evaluation on the heterogeneity of pore structure which greatly affects gas adsorption and transportation in shales. To compare the fractal characteristics between marine and continental shales, nine samples from the Lower Silurian Longmaxi formation in the Sichuan basin and nine from the Middle Jurassic Dameigou formation in the Qaidam basin were collected. Reservoir properties and fractal dimensions were characterized for all the collected samples. In this study, fractal dimensions were originated from the Frenkel–Halsey–Hill (FHH) model with N[Formula: see text] adsorption data. Compared to continental shale, marine shale has greater values of quartz content, porosity, specific surface area and total pore volume but lower level of clay minerals content, permeability, average pore diameter and methane adsorption capacity. The quartz in marine shale is mostly associated with biogenic origin, while that in continental shale is mainly due to terrigenous debris. The N[Formula: see text] adsorption–desorption isotherms exhibit that marine shale has fewer inkbottle-shaped pores but more plate-like and slit-shaped pores than continental shale. Two fractal dimensions ([Formula: see text] and [Formula: see text] were obtained at [Formula: see text] of 0–0.5 and 0.5–1. The dimension [Formula: see text] is commonly greater than [Formula: see text], suggesting that larger pores (diameter [Formula: see text][Formula: see text]nm) have more complex structures than small pores (diameter [Formula: see text][Formula: see text]nm). The fractal dimensions (both [Formula: see text] and [Formula: see text]) positively correlate to clay minerals content, specific surface area and methane adsorption capacity, but have negative relationships with porosity, permeability and average pore diameter. The fractal dimensions increase proportionally with the increasing quartz content in marine shale but have no obvious correlation with that in continental shale. The dimension [Formula: see text] is correlative to the TOC content and permeability of marine shale at a similar degree with dimension [Formula: see text], while the dimension [Formula: see text] is more sensitive to those of continental shale than dimension [Formula: see text]. Compared with dimension [Formula: see text], for two shales, dimension [Formula: see text] is better associated with the content of clay minerals but has worse correlations with the specific surface area and average pore diameter.

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