Pore Size Distribution and Hydraulic Conductivity Characteristics of Solidified Sewage Sludge

2018 ◽  
pp. 389-396
Author(s):  
Xihui Fan ◽  
Wei Zhu ◽  
Haoqing Xu ◽  
Shengwei Wang ◽  
Shi Shu
Keyword(s):  
Hydraulic Conductivity ◽  
Sewage Sludge ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution

scholarly journals Investigation on the Deterioration Mechanism of Tuff Stones Used for the Exteriors at the Former Koshien Hotel

2020 ◽  
Vol 172 ◽  
pp. 20008
Author(s):  
Koki Yamada ◽  
Chiemi Iba ◽  
Tomoko Uno ◽  
Kazuma Fukui ◽  
Daisuke Ogura
Keyword(s):  
Hydraulic Conductivity ◽  
Physical Properties ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Vapor Permeability ◽  
Cultural Significance ◽  
Water Permeation ◽  
Deterioration Mechanism ◽  
Main Factor

The former Koshien Hotel is an historic Japanese architectural structure, where two different tuffs called Nikkaseki and Tatsuyamaishi were used to build the exterior. Despite its cultural significance, the building’s exterior is deteriorating in many ways, with water permeation being the main factor. In this study, the hygrothermal properties of both Nikkaseki and Tatsuyamaishi were measured in order to examine the correlation between deterioration mechanisms and the tuff characteristics in detail. The basic physical properties, pore size distribution, vapor permeability, hydraulic conductivity, and sorption isotherm were measured. The results of a comparison of two tuffs led us to hypothesize that the main reason behind Nikkaseki’s deterioration is expansive freezing, while that of Tatsuyamaishi is caused by repeating dehydration or dry-wet cycles.

Hydraulic conductivity of clay mixed with nanomaterials

2015 ◽  
Vol 52 (6) ◽  
pp. 808-811 ◽  
Author(s):  
C.W.W. Ng ◽  
J.L. Coo
Keyword(s):  
Hydraulic Conductivity ◽  
Aluminum Oxide ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Mercury Intrusion Porosimetry ◽  
Flow Paths ◽  
Mercury Intrusion ◽  
Flexible Wall ◽  
Conductivity Behavior

The focus of this note is to investigate the hydraulic conductivity behavior of clay mixed with nanomaterials. Two different nanomaterials — namely, gamma-aluminum oxide powder (γ-Al2O3) and nano-copper oxide (CuO) — were selected and mixed with clay at different percentages (i.e., 2%, 4%, and 6%). Hydraulic conductivity tests were carried out in a flexible wall permeameter following the ASTM D5084 standard. Mercury intrusion porosimetry (MIP) tests were also carried out to determine the pore-size distribution. At 2% of γ-Al2O3 and nano-CuO, the hydraulic conductivity of clay decreased 30% and 45%, respectively. As the proportion of the nanomaterial increases, the reduction of hydraulic conductivity becomes less prominent as flow paths devoid of nanomaterials are unlikely. Reduction of hydraulic conductivity is due to the pores of clay being clogged by the nanomaterial. Pore-size distribution curves show that the largest pore size reduced by 20% when clay was mixed with 4% nano-CuO.

scholarly journals The impacts of freeze–thaw cycles on saturated hydraulic conductivity and microstructure of saline–alkali soils

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wenshuo Xu ◽  
Kesheng Li ◽  
Longxiao Chen ◽  
Weihang Kong ◽  
Chuanxiao Liu
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Water Content ◽  
Size Distribution ◽  
Saturated Hydraulic Conductivity ◽  
High Water Content ◽  
Soil Permeability ◽  
Freeze Thaw ◽  
Alkali Soil

AbstractStudy on the microscopic structure of saline–alkali soil can reveal the change of its permeability more deeply. In this paper, the relationship between permeability and microstructure of saline–alkali soil with different dry densities and water content in the floodplain of southwestern Shandong Province was studied through freeze–thaw cycles. A comprehensive analysis of soil samples was conducted using particle-size distribution, X-ray diffraction, freeze–thaw cycles test, saturated hydraulic conductivity test and mercury intrusion porosimetry. The poor microstructure of soil is the main factor that leads to the category of micro-permeable soil. The porosity of the local soil was only 6.19–11.51%, and ultra-micropores (< 0.05 μm) and micropores (0.05–2 μm) dominated the pore size distribution. Soil saturated water conductivity was closely related to its microscopic pore size distribution. As the F–T cycles progressed, soil permeability became stronger, with the reason the pore size distribution curve began to shift to the small pores (2–10 μm) and mesopores (10–20 μm), and this effect was the most severe when the freeze–thaw cycle was 15 times. High water content could promote the effects of freeze–thaw cycles on soil permeability and pore size distribution, while the increase of dry density could inhibit these effects. The results of this study provide a theoretical basis for the remediation of saline–alkali soil in the flooded area of Southwest Shandong.

Unsaturated hydraulic conductivity of vineyard soils with high rock fragment content in the Mosel area, Germany

2021 ◽  
Author(s):  
Selina Walle ◽  
Thomas Iserloh ◽  
Manuel Seeger
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Unsaturated Soils ◽  
Hydrological Cycle ◽  
Calculated Data ◽  
Rock Fragment ◽  
Unsaturated Hydraulic Conductivity ◽  
Significant Difference

&lt;p&gt;The study deals with the unsaturated hydraulic conductivity of soils within the scope of the Diverfarming-Project, funded by the EU commission (Horizon 2020 grant agreement no 728003). For this reason, the field work took place in the examined vineyard of the Wawerner Jesuitenberg near Kanzem in the Saar-Mosel valley (Rhineland-Palatinate, Germany). The mentioned parameter is one of the most important specific factors of the hydrological cycle to characterize soil hydraulic properties in the unsaturated soil zone. A mini disc infiltrometer was used to measure the conductivity values at different suctions. The purpose of this study is to determine the plausibility of the fundamentals and the analytical expression of the unsaturated conductivity models in a nearly skeletal soil of schist. In this regard, the mathematical expressions of Mualem (1976), van Genuchten (1980) and Zhang (1997) are focused on calculating the unsaturated hydraulic conductivity. The two variables &amp;#945; and n are analysed in order to better compare between literature specifications and the explicit calculated data of the vineyard&amp;#8217;s soil. As a result, the various developments of &amp;#945; are similar thus the significant difference is based on the value of n. Nevertheless, in consideration of these frame conditions the models represent a suitable mathematical expression of the unsaturated hydraulic conductivity. Furthermore, a range of parameters affecting this conductivity is analysed, particularly with regard to the applied variable soil and cultivation management under the grapevines in the vineyard. Also, the rock fragment cover and the pore size distribution are taken into account. In this context the soil compaction and modified pore size distribution in the wheel tracks stand out due to salient unsaturated hydraulic conductivities at higher tensions. In particular, the stone cover of the contact surface influence the characteristics of the analysed conductivity. Additionally, the connection of stone cover, management and pore size distribution creates a mixture of affected parameters of the unsaturated hydraulic conductivity.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Mualem, Y.: A new model for predicting the hydraulic conductivity of unsaturated porous media, Water Resour. Res, 12, 513&amp;#8211;522, https://doi.org/10.1029/WR012i003p00513, 1976.&lt;/p&gt;&lt;p&gt;Van Genuchten, M.T.: A Closed-form Equation for Predicting the Hydraulic Conductivity of Unsaturated Soils, Soil Sci. Soc. Am. J., 44, 892&amp;#8211;898, https://doi.org/10.2136/sssaj1980.03615995004400050002x, 1980.&lt;/p&gt;&lt;p&gt;Zhang, R.: Determination of Soil Sorptivity and Hydraulic Conductivity from the Disk Infiltrometer, Soil Sci. Soc. Am. J., 61, 1024&amp;#8211;1030, https://doi.org/10.2136/sssaj1997.03615995006100040005x, 1997.&lt;/p&gt;

scholarly journals A Fractal Model of Hydraulic Conductivity for Saturated Frozen Soil

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 369 ◽  
Author(s):  
Lei Chen ◽  
Dongqing Li ◽  
Feng Ming ◽  
Xiangyang Shi ◽  
Xin Chen
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Fractal Theory ◽  
Frozen Soil ◽  
Soil Freezing ◽  
Size Dimension ◽  
Maximum Pore Size

In cold regions, hydraulic conductivity is a critical parameter for determining the water flow in frozen soil. Previous studies have shown that hydraulic conductivity hinges on the pore structure, which is often depicted as the pore size and porosity. However, these two parameters do not sufficiently represent the pore structure. To enhance the characterization ability of the pore structure, this study introduced fractal theory to investigate the influence of pore structure on hydraulic conductivity. In this study, the pores were conceptualized as a bundle of tortuous capillaries with different radii and the cumulative pore size distribution of the capillaries was considered to satisfy the fractal law. Using the Hagen-Poiseuille equation, a fractal capillary bundle model of hydraulic conductivity for saturated frozen soil was developed. The model validity was evaluated using experimental data and by comparison with previous models. The results showed that the model performed well for frozen soil. The model showed that hydraulic conductivity was related to the maximum pore size, pore size dimension, porosity and tortuosity. Of all these parameters, pore size played a key role in affecting hydraulic conductivity. The pore size dimension was found to decrease linearly with temperature, the maximum pore size decreased with temperature and the tortuosity increased with temperature. The model could be used to predict the hydraulic conductivity of frozen soil, revealing the mechanism of change in hydraulic conductivity with temperature. In addition, the pore size distribution was approximately estimated using the soil freezing curve, making this method could be an alternative to the mercury intrusion test, which has difficult maneuverability and high costs. Darcy’s law is valid in saturated frozen silt, clayed silt and clay, but may not be valid in saturated frozen sand and unsaturated frozen soil.

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