Research on the Pore Structure of Alkali-Slag Cement Stone Activated with Water Glass

2011 ◽  
Vol 194-196 ◽  
pp. 899-903 ◽  
Author(s):  
Juan He ◽  
Chang Hui Yang
Keyword(s):  
Fractal Dimension ◽  
Pore Structure ◽  
Water Glass ◽  
Fractal Theory ◽  
Cement Stone ◽  
Pore Surface ◽  
Slag Cement ◽  
Adsorption Method ◽  
Surface Fractal Dimension ◽  
Surface Fractal

In view of the phenomena that alkali-slag cement has high mechanical strength and good impermeability and they are closely related with the pore structure of cement stone,water glass was selected as the alkali activater, nitrogen adsorption method was adopted to study the pore structure of alkali-slag cement stone, while the pore surface fractal dimension was determined by fractal theory. The results show that the pore structure of alkali-slag cement stone posesses obvious fractal characters and that fits the Frenkel-Halsey-Hill(FHH) model quite well.So the pore surface fractal dimension can be used to synthetically evaluate the superior or inferior of the pore structure of cement stone.

Research on Fractal Characteristics of Cement-Based Materials by Nitrogen Adsorption Method

2011 ◽  
Vol 415-417 ◽  
pp. 1545-1552 ◽  
Author(s):  
Ming Tang ◽  
Jing Qi Li
Keyword(s):  
Fractal Dimension ◽  
Pore Structure ◽  
Surface Area ◽  
Nitrogen Adsorption ◽  
Surface Characteristics ◽  
Adsorption Method ◽  
Surface Fractal Dimension ◽  
Surface Fractal ◽  
Cement Based Materials ◽  
Fractal Characteristics

In order to confirm the surface fractal dimension of the internal pore of complex porous materials by means of the FHH model and nitrogen adsorption method. Study the change rule on fractal characteristics of the pore of cement based materials further. The results shows that, surface area of the complex internal structure of cement based materials has the fractal characteristics observably. Testing and evaluating the fractal characteristics on surface area of the pore of cement-based materials is effective by nitrogen adsorption method. It is good for analyzing surface characteristics of pore structure further. Surface fractal dimension of pore structure and surface area have not good correlation. The characteristics and conclusion that quality fractal dimension of powder and surface area evaluating fineness of powder have not very good correlation is consistent.

Application of Fractal Theory on River Bed Form

2012 ◽  
Vol 212-213 ◽  
pp. 236-240 ◽  
Author(s):  
Yin Jun Zhou ◽  
Fei Li ◽  
Li Chen ◽  
Zhong Wu Jin ◽  
Jun Wang
Keyword(s):  
Fractal Dimension ◽  
Surface Area ◽  
Fractal Theory ◽  
Irregular Boundary ◽  
Surface Fractal Dimension ◽  
Surface Fractal ◽  
River Bed ◽  
Bed Form ◽  
Fractal Characteristics ◽  
River Pattern

Fractal theory is used to describe river bed form. Based on improvements in some aspects of Surface area – Scale Method, such as, estimation of surface area, boundary treatment and so on, the calculation method of surface fractal dimension with irregular boundary is obtained, and the new method has good application on the bed surface fractal dimension calculation. The fractal characteristics of river bed surface morphology are discussed by combination with river-pattern, river regime, river process and changes of BSD. BSD can be used to study some related problems, such as analysis of river regime, distinction of river pattern, calculation of river resistance and so on.

Pores in PAN-Based Carbon Fiber and Effects of Pore Defects on Mechanical Properties

2007 ◽  
Vol 546-549 ◽  
pp. 1665-1668 ◽  
Author(s):  
Zhong Hua ◽  
Ya Juan Zhong ◽  
Dong Feng Li
Keyword(s):  
Fractal Dimension ◽  
Carbon Fiber ◽  
Small Angle ◽  
Unit Volume ◽  
Fractal Theory ◽  
Surface Fractal Dimension ◽  
X Ray ◽  
X Ray Scattering ◽  
Surface Fractal ◽  
Ray Scattering

Specimens of polyacrylonitrile-based carbon fiber (PAN-CF) with different graphitization temperatures were investigated by small angle X-ray scattering (SAXS) and wide angle X-ray diffraction (WAXD). Based on SAXS intensity data and fractal theory, surface fractal dimension of the pore in PAN-CF was given by small angle X-ray scattering intensity method, the size of various pores and the bigger pore percentage of unit volume were calculated by Fankuchen gradual tangent method. The result indicatesd that the size and surface fractal dimension of the pores, the bigger pore percentage of unit volume increased with increasing graphitization temperature. This forms stress concentration easily, which leads to the decreasing of tensile strength.

FRACTAL MODELS FOR GAS–WATER TRANSPORT IN SHALE POROUS MEDIA CONSIDERING WETTING CHARACTERISTICS

Fractals ◽  
2020 ◽  
Vol 28 (07) ◽  
pp. 2050138
Author(s):  
QI ZHANG ◽  
XINYUE WU ◽  
QINGBANG MENG ◽  
YAN WANG ◽  
JIANCHAO CAI
Keyword(s):  
Fractal Dimension ◽  
Pore Structure ◽  
Pore Pressure ◽  
Surface Diffusion ◽  
Water Transport ◽  
Relative Permeability ◽  
Fluid Transport ◽  
Water Saturation ◽  
Fractal Theory ◽  
Gas Slippage

Complicated gas–water transport behaviors in nanoporous shale media are known to be influenced by multiple transport mechanisms and pore structure characteristics. More accurate characterization of the fluid transport in shale reservoirs is essential to macroscale modeling for production prediction. This paper develops the analytical relative permeability models for gas–water two-phase in both organic and inorganic matter (OM and IM) of nanoporous shale using the fractal theory. Heterogeneous pore size distribution (PSD) of the shale media is considered instead of the tortuous capillaries with uniform diameters. The gas–water transport models for OM and IM are established, incorporating gas slippage described by second-order slip condition, water film thickness in IM, surface diffusion in OM, and the total organic carbon. Then, the presented model is validated by experimental results. After that, sensitivity analysis of gas–water transport behaviors based on pore structure properties of the shale sample is conducted, and the influence factors of fluid transport behaviors are discussed. The results show that the gas relative permeability is larger than 1 at the low pore pressure and water saturation. The larger pore pressure causes slight effect of gas slippage and surface diffusion on the gas relative permeability. The larger PSD fractal dimension of IM results in larger gas relative permeability and smaller water relative permeability. Besides, the large tortuosity fractal dimension will decrease the gas flux at the same water saturation, and the surface diffusion decreases with the increase of tortuosity fractal dimension of OM and pore pressure. The proposed models can provide an approach for macroscale modeling of the development of shale gas reservoirs.

FRACTAL PORE STRUCTURE MODEL AND MULTILAYER FRACTAL ADSORPTION IN SHALE

Fractals ◽  
2014 ◽  
Vol 22 (03) ◽  
pp. 1440010 ◽  
Author(s):  
LIEHUI ZHANG ◽  
JIANCHAO LI ◽  
HONGMING TANG ◽  
JINGJING GUO
Keyword(s):  
Fractal Dimension ◽  
Pore Structure ◽  
Saturated Vapor ◽  
Adsorption Property ◽  
Fractal Theory ◽  
Complex Structure ◽  
Structure Model ◽  
Adsorption Model ◽  
Adsorption Volume ◽  
Isothermal Adsorption

The complex structure and surface property of porous media have significant impact on its accumulation and adsorption capacity. Based on the fractal theory, this paper presents a fractal pore structure model for shales. The effect of different pore structures on fractal dimension is discussed, and the influence of fractal dimension and pore size distribution on porosity is also analyzed. It is shown that the fractal dimension D decreases with the increase of structure parameter q/m for a certain pore diameter ratio, and porosity has positive relationship with fractal dimension. This paper also presents a multilayer fractal adsorption model which takes into account the roughness of adsorption surface by using fractal theory. With the introduction of pseudo-saturated vapor pressure in the supercritical temperature condition, the proposed adsorption model can be applied into a wider range of temperature. Based on the low-pressure nitrogen adsorption and methane isothermal adsorption experiments, the effect of fractal dimension on the adsorption behavior of shales is discussed. Fractal dimension has significant impact on the surface adsorption property and adsorption layer number n. The monolayer saturated adsorption volume Vm increases with the increase of D, while parameter C has the opposite variation trend. Finally, the optimal combination of fractal parameters for describing pore structure of shale samples is selected.

scholarly journals Effect of Grain Size on Microscopic Pore Structure and Fractal Characteristics of Carbonate-Based Sand and Silicate-Based Sand

2021 ◽  
Vol 5 (4) ◽  
pp. 152
Author(s):  
Shao-Heng He ◽  
Zhi Ding ◽  
Hai-Bo Hu ◽  
Min Gao
Keyword(s):  
Grain Size ◽  
Fractal Dimension ◽  
Pore Structure ◽  
Pore Size ◽  
Quartz Sand ◽  
Glass Bead ◽  
Fractal Theory ◽  
Calcareous Sand ◽  
Wide Range ◽  
Fractal Characteristics

In this study, a series of nuclear magnetic resonance (NMR) tests was conducted on calcareous sand, quartz sand, and glass bead with a wide range of grain sizes, to understand the effect of grain size on the micro-pore structure and fractal characteristics of the carbonate-based sand and silicate-based sand. The pore size distribution (PSD) of the tested materials were obtained from the NMR T2 spectra, and fractal theory was introduced to describe the fractal properties of PSD. Results demonstrate that grain size has a significant effect on the PSD of carbonate-based sand and silicate-based sand. As grain size increases, the PSD of sands evolves from a binary structure with two peaks to a ternary structure with three peaks. The increase in the grain size can cause a remarkable increase in the maximum pore size. It is also found that the more irregular the particle shape, the better the continuity between the large and medium pores. In addition, grain size has a considerable effect on the fractal dimension of the micro-pore structure. The increase of grain size can lead to a significant increase in the heterogeneity and fractal dimension in PSD for calcareous sand, quartz sand and glass bead.

STUDY ON EVOLUTION OF FRACTAL DIMENSION FOR FRACTURED COAL SEAM UNDER MULTI-FIELD COUPLING

Fractals ◽  
2020 ◽  
Vol 28 (04) ◽  
pp. 2050072 ◽  
Author(s):  
GUANNAN LIU ◽  
BOMING YU ◽  
DAYU YE ◽  
FENG GAO ◽  
JISHAN LIU
Keyword(s):  
Fractal Dimension ◽  
Coal Seam ◽  
Pore Structure ◽  
Fractal Theory ◽  
In Situ Stress ◽  
Volume Strain ◽  
Fracture Length ◽  
Field Coupling ◽  
Pore Evolution ◽  
Fractured Coal

In the process of gas extraction, fracture-pore structure significantly influences the macroscopic permeability of coal seam. However, under the multi-field coupling, the mechanism of coal seam fracture-pore evolution remains to be clarified. In this paper, considering the effect of adsorption expansion, the fractal theory for porous media coupled with the multi-field model for coal seam is considered, and a multi-field coupling mechanical model is constructed by considering the influence of fracture-pore structure. Furthermore, the evolution mechanism of fractal dimension with physical and mechanical parameters of coal seam is studied. It is found that the fractal dimension for coal seam is inversely proportional to mining time and in situ stress, proportional to elastic modulus, Langmuir volume constant and Langmuir volume strain constant, and inversely proportional to Langmuir pressure constant. Compared with other factors, Langmuir pressure constant and Langmuir volume strain constant have the significance influence on the fractal dimension for the fracture length.

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