scholarly journals Study on the Relationship between Pore Structure and Uniaxial Compressive Strength of Cemented Paste Backfill by Using Air-Entraining Agent

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Fengwen Zhao ◽  
Jianhua Hu ◽  
Dongjie Yang ◽  
Ye Kuang ◽  
Hongxing Xiao ◽  
...  
Keyword(s):  
Pore Structure ◽  
Fractal Theory ◽  
Total Pore Volume ◽  
Linear Increase ◽  
Theory Analysis ◽  
Structure Changes ◽  
Small Pore ◽  
Paste Backfill ◽  
Air Entraining Agents ◽  
The Relationship

To control pores in the backfill, the air-entraining agents (AEAs) are used as an admixture to realize the pore structure changes under artificial action and explore the effect of pore structure on strength. Two AEAs at different dosages were added to the backfill. The relationship was then analyzed between them from the macro- and mesoscopic aspects. The results indicate that AEA can regulate pore structure changes of AEACPB. With the increase in AEA content, the total pore volume of different pore sizes in AEACPB increases, in which the proportion of big and medium pore gradually increases while the proportion of small pore gradually decreases. The AEACPB’s UCS is linearly negatively correlated with the porosity and pore percentage, which is the primary factor affecting the AEACPB of the pore structure. When the total pores’ volume in the AEACPB is constant, the influence of different pore structures differs. A higher proportion of small pores leads to a linear increase in strength; a higher proportion of medium pores leads to a linear decrease in strength; and a higher proportion of big pores leads to an exponential decrease in strength. And the fractal dimension has a linear negative correlation with the UCS by fractal theory analysis.

scholarly journals Effects of Clay Content on Pore Structure Characteristics of Marine Soft Soil

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1160
Author(s):  
Wencan Jiao ◽  
Dong Zhou ◽  
Yetian Wang
Keyword(s):  
Fractal Dimension ◽  
Pore Structure ◽  
Pore Volume ◽  
Fractal Theory ◽  
Soft Soil ◽  
Total Pore Volume ◽  
Clay Content ◽  
Beibu Gulf ◽  
Structure Characteristics ◽  
Small Pore

This study investigates the pore structure characteristics of a marine soft soil of the Beibu Gulf, Guangxi Province, China and its variation with clay content. Pore-size distribution was measured by Mercury intrusion porosimetry (MIP) and analyzed based on fractal theory. The analysis of the results relies on the distinction of several types of pores: micropores, small pores, mesopores and macropores, separated by the critical pore diameters of 0.02 μm, 0.18 μm and 0.78 μm, respectively. Mesopores and small pores were dominant, accounting for more than 75% of the total pore volume. Small pore volume increases with clay content at the expense of the mesopore volume. Between 22.31% and 32.31% clay, the connectivity of pores improves with clay content, while the tortuosity of pores increases from 22.31% to 32.31% of clay and then decreases between 32.31% and 37.31% clay. Marine soft soil in the Beibu Gulf is characterized by multiple fractal dimensions. Macropores had a large (close to 3) fractal dimension, independent of clay content. Mesopores and small pores had a smaller fractal dimension comprised between 2.1 and 2.4, while the fractal dimension of micropores did not exceed 1.5. The fractal dimension of mesopores and micropores are influenced significantly by the clay content. The study of the porosity of the marine soft soil of the Beibu Gulf could serve as a useful basis for the prediction of its hydraulic properties.

scholarly journals The Evolutionary Characteristics of Reservoir Microstructure under Long-Term Waterflooding Development and Its Fractal Description

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Fengjiao Wang ◽  
Xu Wang ◽  
Yikun Liu ◽  
Qingjun Deng ◽  
Jianjun Xu ◽  
...  
Keyword(s):  
Pore Structure ◽  
Physical Simulation ◽  
Structural Parameters ◽  
Fractal Theory ◽  
Evolution Model ◽  
Structure Evolution ◽  
Before And After ◽  
Water Cut ◽  
The Relationship

Generally, long-term waterflooding development often leads to the change of reservoir pore and clay mineral composition, which results in the change of permeability and wettability. In order to explore the relationship between core micropore structure and water cut, based on physical simulation experiments and fractal theory, we proposed a fractal evolutionary model to describe the evolution characteristics of microstructure of long-term water driving reservoirs. In this paper, core pore structure by SEM was first conducted to analyze the change of core pore structure before and after waterflooding under the conditions of magnification of 200 times, 800 times, and 2000 times, respectively. Then, conventional and constant rate mercury injection tests were combined to perform the comparative analysis of core structural parameters before and after waterflooding. Finally, a micropore-throat structure evolution model of core was established. Research shows that the connectivity of larger pores becomes better after long-term water driving, the degree of heterogeneity weakens, and the micro heterogeneity of small pores becomes stronger and stronger. The throat characteristics change in a complex manner, the radius tends to increase, and the sorting becomes better, while the connectivity of small throat changes complex. In general, the heterogeneity of throat increases with the time of water injection in reservoirs with low porosity and permeability. On the basis of fractal theory and variation characteristics of rock pore structure in water driving reservoirs, we have established a micropore-throat structure evolution model of core pore-throat characteristics. This fractal evolution model quantitatively characterized the complexity and evolution law of pore structure and clarified the relationship between fractal dimension of core pore structure and water cut under different stages of water driving.

scholarly journals Capillary Water Absorption and Micro Pore Connectivity of Concrete with Fractal Analysis

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 892
Author(s):  
Xiangqun Ding ◽  
Xinyu Liang ◽  
Yichao Zhang ◽  
Yanfeng Fang ◽  
Jinghai Zhou ◽  
...  
Keyword(s):  
Pore Structure ◽  
Water Absorption ◽  
Fractal Theory ◽  
Mineral Admixtures ◽  
Capillary Water ◽  
Capillary Water Absorption ◽  
Connectivity Probability ◽  
Fractal Characteristics ◽  
Different Diameters ◽  
The Relationship

This study focuses on the relationship between the complexity of pore structure and capillary water absorption of concrete, as well as the connection behavior of concrete in specific directions. In this paper, the water absorption of concrete with different binders was tested during the curing process, and the pore structure of concrete was investigated by mercury intrusion porosimetry (MIP). The results show that the water absorption of concrete with mineral admixtures is lower, mainly due to the existence of reasonable pore structure. The effect of slag on concrete modification is more remarkable comparing with fly ash. In addition, the analysis shows that the pore with different diameters has different fractal characteristics. The connectivity probability and water absorption of unidirectional chaotic pore are linearly correlated with the pore diameter of 50–550 nm, and the correlation coefficient reaches a very significant level, and detailed analysis was undertaken to interpret these results based on fractal theory.

Study on the Permeability Model of the Porous Concrete

2011 ◽  
Vol 374-377 ◽  
pp. 1369-1373 ◽  
Author(s):  
Fang Ran Zhao ◽  
Mian Mian Chen ◽  
Zhao Lu Ding
Keyword(s):  
Pore Structure ◽  
Test Piece ◽  
Experimental Results ◽  
Effective Model ◽  
Permeability Model ◽  
Porous Concrete ◽  
Structure Changes ◽  
Proposed Model ◽  
Capillary Bundle ◽  
The Relationship

This paper presents an effective model which can equivalently regard the pores in the porous concrete as a series of capillary bundles with the same diameter due to the complexity of the pores in the porous concrete. The proposed model was used to calculated the total flows of all capillary bundles in the test piece by the single capillary bundle calculation approach from the Hagen-Poiseuille theorem, and together with the well known Darcy theorem to determine the relationship among the flow of the porous concrete, the diameter of pore and the minus of up and down water pressures. The experimental results show that the permeability of the porous concrete mainly depends on the pores with diameter more than 4.12mm, and the pore structure changes obviously when the valid porosity of the porous concrete is greater than 25%.

scholarly journals Relationship between Water-Permeability Coefficient and Pore-Structure Indicators of Cementitious Materials

2018 ◽  
Author(s):  
Yuya Sakai
Keyword(s):  
Pore Structure ◽  
Water Permeability ◽  
Total Pore Volume ◽  
Cementitious Materials ◽  
Critical Threshold ◽  
Determination Coefficient ◽  
Water Permeability Coefficient ◽  
The Relationship ◽  
Very High ◽  
Median Pore

To understand the relationship between water permeability and the pore structure of cementitious materials, literature that studied both water permeability and the pore structure are reviewed, and their correlation is studied. Although the majority of this data is for cement paste, mortar, concrete, and cemented soil are also included. Based on this study, it is established the determination coefficient between water permeability and the total pore volume is very low; however, those between water permeability and the critical, threshold, and median pore diameters, respectively, are moderate. On the other hand, the threshold pore diameter, derived based on the percolation theory, exhibits a very high determination coefficient. The calculated water permeability, using the Katz and Thompson equation, agrees with the reported water permeability quantitatively to a certain level, but is overestimated.

Calendering Effects on Coating Pore Structure and Ink Setting Behavior

TAPPI Journal ◽  
2010 ◽  
Vol 9 (1) ◽  
pp. 27-35 ◽  
Author(s):  
PETER RESCH ◽  
WOLFGANG BAUER ◽  
ULRICH HIRN
Keyword(s):  
Pore Structure ◽  
Mercury Porosimetry ◽  
Total Pore Volume ◽  
Theoretical Models ◽  
Surface Appearance ◽  
Coated Papers ◽  
Structure Changes ◽  
Ink Setting ◽  
Paper Gloss ◽  
Reduced Surface

Coating layer pore structure significantly affects surface appearance, optical properties, and print-ability performance of multiply coated papers. Generally, fast ink setting can be realized by use of fine pigments, or pigments with steep particle size distribution. Ink-paper interaction of coated papers also changes significantly in calendering. The objective of this study was to better understand the influence of calendering on the pore structure of multilayered coated papers and to highlight the effect of this pore structure change on ink setting behavior. Laboratory calendering trials demonstrated that the pore structure of calendered paper is reduced with increased calendering temperatures. Mercury porosimetry and image analysis of scanning electron microscope images of calendered papers highlighted the gradual reduction of total pore volume, which, in combination with the reduced surface porosity, resulted in slower ink setting. If ink setting speed is to be preserved, calendering at low surface temperatures and a higher number of nip passes is preferred to reach a desired paper gloss level. Results also were compared to common theoretical models for liquid penetration into porous structures. These models can also be used to describe the influence of calendering-induced pore structure changes on ink setting. This work demonstrates optimization of calendering parameters to reach a balance for paper gloss and ink setting. The optimum depends on the machine equipment available and has to be checked separately for each concept of multiply coated paper and calender conditions.

The Pore Structure Multifractal Research of Low Silicon Sinter

2013 ◽  
Vol 750-752 ◽  
pp. 2221-2224
Author(s):  
Qing Jun Zhang ◽  
Qing Liu ◽  
Chun Liang Yan ◽  
Yu Zhu Zhang
Keyword(s):  
Pore Structure ◽  
Fractal Theory ◽  
Multifractal Spectrum ◽  
Mercury Intrusion ◽  
Metallurgical Properties ◽  
Multifractal Theory ◽  
Different Content ◽  
The Relationship

With the combination of fractal theory and metallurgical properties of low silicon sinter, the influence of metallurgical properties in different content of R, MgO, SiO2 and C is analyzed on the condition of existing experiment and fuel, and by using the mercury intrusion machine it measured the volume of micro-pore structure after broken of low silicon sinter; and it combined with the multifractal theory measured multifractal spectrum for the pore structure, which is established the relationship between with the metallurgical properties and fractal theory.

Analysis of Collapsible Loess Microstructure at Fractal Theory Based

2012 ◽  
Vol 204-208 ◽  
pp. 614-617
Author(s):  
Ming Yuan Shi ◽  
Zong Fang Chen ◽  
Hong Yan Zhang
Keyword(s):  
Fractal Dimension ◽  
Pore Structure ◽  
Linear Relationship ◽  
Pore Radius ◽  
Fractal Theory ◽  
Fractal Characteristic ◽  
Geological Age ◽  
Collapsible Loess ◽  
Fractal Character ◽  
The Relationship

On the basis of publicized data, the fractal character of pore structure in loess is studied. We have determined fractal characteristic pore radius and discussed the relationship between fractal character values and collapsibility. Results show that there is a good linear relationship between and collapsibility, and fractal dimension can reflect geological age of loess section.

scholarly journals The impact of changes in pore structure on the compressive strength of sulphoaluminate cement concrete at high temperature

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
J.J.K. Tchekwagep ◽  
P. Zhao ◽  
S. Wang ◽  
S. Huang ◽  
X. Cheng
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
Elevated Temperatures ◽  
Nitrogen Adsorption ◽  
Cement Concrete ◽  
Constant Weight ◽  
Sulphoaluminate Cement ◽  
Structure Changes ◽  
The Impact ◽  
The Relationship

Abstract The internal pore structure of sulphoaluminate cement concrete (SACC) significantly affects its mechanical properties. The main purpose of this study was to establish the relationship between pore structure changes and compressive strength after exposure to elevated temperatures. SACC samples that had been cured for 12 months were dried to a constant weight and then exposed to different temperatures (100 °C, 200 °C and 300 °C), after which the compressive strength and pore structure were measured. The pore structure of SACC was quantitatively described by mercury intrusion porosimetry (MIP) and nitrogen adsorption results. The results showed that with increased temperature, the porosity of the SACC samples also increased and the pore structure was gradually destroyed. Moreover, the SACC’s compressive strength gradually decreased with increasing temperature. The relationship between compressive strength and porosity was in close agreement with the compressive strength–porosity equation proposed by Schiller. Therefore, after extensive exposure to elevated temperature, the changes in SACC’s compressive strength can be quantitatively described by the Schiller equation.

scholarly journals Review on Fractal Analysis of Porous Metal Materials

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
J. Z. Wang ◽  
J. Ma ◽  
Q. B. Ao ◽  
H. Zhi ◽  
H. P. Tang
Keyword(s):  
Fractal Dimension ◽  
Pore Structure ◽  
Fractal Analysis ◽  
Material Characterization ◽  
Fractal Theory ◽  
Porous Metal ◽  
Processing Method ◽  
The Past ◽  
Metal Materials ◽  
The Relationship

Porous metal materials are multifunctional lightweight materials and have been used widely in industry. The structural and functional characters of porous metal materials depend on the pore structure which can be described effectively by the fractal theory. This paper reviews the major achievements on fractal analysis of pore structure of porous metal materials made by State Key Laboratory of Porous Metal Materials, China, over the past few years. These include (i) designing and developing a set of novel fractal analytical software of porous metal materials, (ii) the influence of material characterization and image processing method on the fractal dimension, and (iii) the relationship between the material performance and the fractal dimension. Finally, the outlooks of fractal theory applied in porous metal materials are discussed.

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