Pore-structure models of hydraulic conductivity for permeable pavement

2011 ◽  
Vol 399 (3-4) ◽  
pp. 148-157 ◽  
Author(s):  
X. Kuang ◽  
J. Sansalone ◽  
G. Ying ◽  
V. Ranieri
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Structure ◽  
Permeable Pavement

scholarly journals Examining the effect of pore size distribution and shape on flow through unsaturated peat using computed tomography

2009 ◽  
Vol 13 (10) ◽  
pp. 1993-2002 ◽  
Author(s):  
F. Rezanezhad ◽  
W. L. Quinton ◽  
J. S. Price ◽  
D. Elrick ◽  
T. R. Elliot ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Hydraulic Conductivity ◽  
Pore Structure ◽  
Pore Size ◽  
Soil Water ◽  
Water Pressure ◽  
Peat Soil ◽  
Pressure Head ◽  
Peat Soils ◽  
Unsaturated Hydraulic Conductivity

Abstract. The hydraulic conductivity of unsaturated peat soil is controlled by the air-filled porosity, pore size and geometric distribution as well as other physical properties of peat materials. This study investigates how the size and shape of pores affects the flow of water through peat soils. In this study we used X-ray Computed Tomography (CT), at 45 μm resolution under 5 specific soil-water pressure head levels to provide 3-D, high-resolution images that were used to detect the inner pore structure of peat samples under a changing water regime. Pore structure and configuration were found to be irregular, which affected the rate of water transmission through peat soils. The 3-D analysis suggested that pore distribution is dominated by a single large pore-space. At low pressure head, this single large air-filled pore imparted a more effective flowpath compared to smaller pores. Smaller pores were disconnected and the flowpath was more tortuous than in the single large air-filled pore, and their contribution to flow was negligible when the single large pore was active. We quantify the pore structure of peat soil that affects the hydraulic conductivity in the unsaturated condition, and demonstrate the validity of our estimation of peat unsaturated hydraulic conductivity by making a comparison with a standard permeameter-based method. Estimates of unsaturated hydraulic conductivities were made for the purpose of testing the sensitivity of pore shape and geometry parameters on the hydraulic properties of peats and how to evaluate the structure of the peat and its affects on parameterization. We also studied the ability to quantify these factors for different soil moisture contents in order to define how the factors controlling the shape coefficient vary with changes in soil water pressure head. The relation between measured and estimated unsaturated hydraulic conductivity at various heads shows that rapid initial drainage, that changes the air-filled pore properties, creates a sharp decline in hydraulic conductivity. This is because the large pores readily lose water, the peat rapidly becomes less conductive and the flow path among pores, more tortuous.

A Study of a New Ceramic Membrane for Use in Hemodialysis

2004 ◽  
Author(s):  
Zhongping Huang ◽  
Weiming Zhang ◽  
Sonja M. Tang ◽  
Jianping Yu ◽  
Stephen J. Lai-Fook ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Hydraulic Conductivity ◽  
Oxalic Acid ◽  
Pore Structure ◽  
Pore Size ◽  
Ceramic Membrane ◽  
Anodic Alumina ◽  
Pore Distribution ◽  
Self Organized ◽  
Hemodialysis Membrane

The non-uniformity of pore size and pore distribution of the current hemodialysis membrane results in low efficiency of uremic solute removal as well as the loss of albumin. By using nano technology, an anodic alumina membrane (ceramic membrane) with self-organized nano-pore structure was produced. The objective of this study was to investigate the correlation between various anodization conditions and the pore characteristics of the ceramic membrane as a potential use in artificial kidney / hemodialysis. An aluminum thin film was oxidized in two electrolytes consisting of 3% and 5% sulfuric acid and 2.7% oxalic acid. The applied voltages were 12.5, 15, 17.5 and 20 (V) for sulfuric acid and 20, 30, 40 and 50 (V) for oxalic acid. Pore size and porosity were determined by analyzing scanning electron microscopy (SEM) images and hydraulic conductivity was measured. Pore size increased linearly with voltage. Acid concentration affected pore formation but not pore size and pore distribution. Hydraulic conductivity of the ceramic membrane was higher than that of polymer dialysis membrane. The optimal formation conditions for self-organized nano-pore structure of ceramic membrane were 12.5–17.5V in 3–5% sulfuric acid at 0 °C. These conditions produced ceramic membranes with pores of ~ 10 nm diameter. Conclusion: Anodic alumina technology reliably produced in quantity structures with pore sizes in the 10–50 nm diameter range. Because of more uniform pore size, high porosity, high hydraulic conductivity and resistance to high temperature, the ceramic membrane has potential for future application as a hemodialysis membrane.

Comparative Analysis of Soluble Phosphate Amendments for the Remediation of Heavy Metal Contaminants: Effect on Sediment Hydraulic Conductivity

2006 ◽  
Vol 3 (3) ◽  
pp. 219 ◽  
Author(s):  
Dawn M. Wellman ◽  
Jonathan P. Icenhower ◽  
Antoinette T. Owen
Keyword(s):  
United States ◽  
Hydraulic Conductivity ◽  
Pore Structure ◽  
Pore Space ◽  
The United States ◽  
Water Soluble ◽  
Department Of Energy ◽  
United States Department ◽  
Soluble Phosphate ◽  
Long Chain

Environmental Context. The contamination of surface and subsurface geologic media by heavy metals and radionuclides is a significant problem within the United States Department of Energy complex as a result of past nuclear operations. Water-soluble phosphate compounds provide a means to inject phosphorus into subsurface contaminant plumes, to precipitate metal ions from solution. However, phosphate phases can form within the sedimentary pore structure to block a fraction of the pore space and inhibit further remediation of the contaminant plume. A series of tests have been conducted to evaluate changes in sedimentary pore structure during the application of several proposed phosphate remediation amendments. Abstract. A series of conventional, saturated column experiments have been conducted to evaluate the effect of utilizing in situ, soluble, phosphate amendments for subsurface metal remediation on sediment hydraulic conductivity. Experiments have been conducted under mildly alkaline and calcareous conditions representative of conditions commonly encountered at sites across the arid western United States, which have been used in weapons and fuel production and display significant subsurface contamination. Results indicate that the displacement of a single pore volume of either sodium monophosphate or phytic acid amendments causes approximately a 30% decrease in the hydraulic conductivity of the sediment. Long-chain polyphosphate amendments afford no measurable reduction in hydraulic conductivity. These results demonstrate (1) the efficacy of long-chain polyphosphate amendments for subsurface metal sequestration; and (2) the necessity of conducting dynamic experiments to evaluate the effects of subsurface remediation.

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.

scholarly journals Measurement and simulation of the effect of compaction on the pore structure and saturated hydraulic conductivity of grassland and arable soil

2010 ◽  
Vol 46 (5) ◽  
Author(s):  
G. P. Matthews ◽  
G. M. Laudone ◽  
A. S. Gregory ◽  
N. R. A. Bird ◽  
A. G. de G. Matthews ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Structure ◽  
Saturated Hydraulic Conductivity ◽  
Arable Soil

scholarly journals Effect of the choice of different methods on the permeable pavement hydraulic characterization and hydrological classification

2021 ◽  
Vol 69 (3) ◽  
pp. 332-346
Author(s):  
Larissa Virgínia da Silva Ribas ◽  
Artur Paiva Coutinho ◽  
Laurent Lassabatere ◽  
Severino Martins dos Santos Neto ◽  
Suzana Maria Gico Lima Montenegro ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Numerical Models ◽  
Soil Classification ◽  
Saturated Hydraulic Conductivity ◽  
Water Infiltration ◽  
Infiltration Capacity ◽  
Characterization Methods ◽  
Permeable Pavement ◽  
Permeable Pavements

Abstract The permeable pavement is a compensatory drainage technique for urban waters that aims to control runoff and to ensure ideal hydrological conditions. This work had as main objectives to evaluate the infiltration capacity of a permeable pavement (PP) at real scale, through analytical and numerical modeling. It relies on water infiltration experiments and related modeling for the hydrodynamic characterization of the coating layer (saturated hydraulic conductivity, Ks , and sorptivity, S). A large panel of analytical and numerical models was considered, and several estimates were obtained. Then, the criteria for the evaluation of the maintenance requirement of the permeable pavements were computed for all the Ks -estimates considering the NCRS standards (assessment of permeability levels). The results indicated nice fits and accurate estimates for both the saturated hydraulic conductivity and the sorptivity. However, the Ks -estimates depended on the considered model and led to contrasting results in terms of classification. For 8 of the 9 models, the value of the Ks -estimate leads to the classification of “Group A” of the NCRS soil classification, meaning a very permeable material. In contrasts, the last method (numerical inverse modeling) classified the permeable pavement as “Group D”, i.e., soils with low permeability. Those results show the importance of the selection of characterization methods regarding the assessment of the hydrological classification of permeable pavements.

scholarly journals Permeable Asphalt Hydraulic Conductivity and Particulate Matter Separation With XRT

2021 ◽  
Author(s):  
Mariana Marchioni ◽  
Roberto Fedele ◽  
Anita Raimondi ◽  
John Sansalone ◽  
Gianfranco Becciu
Keyword(s):  
Particulate Matter ◽  
Hydraulic Conductivity ◽  
Pore Structure ◽  
Management Practice ◽  
Flow Characteristics ◽  
Chemical Separation ◽  
Noise Pollution ◽  
Material Behavior ◽  
Rainfall Simulation ◽  
Structure Parameters

Abstract Permeable asphalt (PA) is a composite material with an open graded mix design that provides a pore structure facilitating stormwater infiltration. PA is often used as a wearing course for permeable pavements and on roadways to reduce aquaplaning and noise pollution. The pore structure functions as a filter promoting particulate matter (PM) separation. The infiltrating flow characteristics are predominately dependent on pore diameter and pore interconnectivity. X-Ray microTomography (XRT) has been successfully used to estimate these parameters that are otherwise difficult to obtain through conventional gravimetric methods. The pore structure parameters allow modeling of hydraulic conductivity (k) and filtration mechanisms; required to examine the material behavior for infiltration and PM separation. Pore structure parameters were determined through XTR for three PA mixtures. The Kozeny-Kovàv model was implemented to estimate k. PM separation was tested using a pore-to-PM diameter categorical model. This filtration mechanism model was validated with data using rainfall simulation. The filtration model provided a good correlation between measured and modeled data. The identification of filtration mechanisms and k facilitate the design and evaluation of permeable pavement systems as a best management practice (BMP) for runoff volume and flow as well as PM and PM-partitioned chemical separation.

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