scholarly journals Effect of Confining Conditions on the Hydraulic Conductivity Behavior of Fiber-Reinforced Lime Blended Semiarid Soil

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3120
Author(s):  
Abdullah Ali Shaker ◽  
Mosleh Ali Al-Shamrani ◽  
Arif Ali Baig Moghal ◽  
Kopparthi Venkata Vydehi
Keyword(s):  
Hydraulic Conductivity ◽  
Expansive Soils ◽  
Dry Weight ◽  
Rigid Wall ◽  
Saturated Hydraulic Conductivity ◽  
Morphological Properties ◽  
Expansive Clay ◽  
Confining Pressures ◽  
Flexible Wall ◽  
Fiber Materials

The hydraulic properties of expansive soils are affected due to the formation of visible cracks in the dry state. Chemical stabilization coupled with fiber reinforcement is often considered an effective strategy to improve the geotechnical performance of such soils. In this study, hydraulic conductivity tests have been conducted on expansive clay using two different types of fibers (fiber cast (FC) and fiber mesh (FM)) exhibiting different surface morphological properties. The fiber parameters include their dosage (added at 0.2% to 0.6% by dry weight of soil) and length (6 and 12 mm). Commercially available lime is added to ensure proper bonding between clay particles and fiber materials, and its dosage was fixed at 6% (by dry weight of the soil). Saturated hydraulic conductivity tests were conducted relying on a flexible wall permeameter on lime-treated fiber-blended soil specimens cured for 7 and 28 days. The confining pressures were varied from 50 to 400 kPa, and the saturated hydraulic conductivity values (ksat) were determined. For FC fibers, an increase in fiber dosage caused ksat values to increase by 9.5% and 94.3% for the 6 and 12 mm lengths, respectively, at all confining pressures and curing periods. For FM fibers, ksat values for samples mixed with 6 mm fiber increased by 12 and 99.2% for 6 and 12 mm lengths, respectively for all confining pressures at the end of the 28-day curing period. The results obtained from a flexible wall permeameter (FWP) were compared with those of a rigid wall permeameter (RWP) available in the literature, and the fundamental mechanism responsible for such variations is explained.

The ability of Distichlis spicata to grow sustainably within a saline discharge zone while improving the soil chemical and physical properties

Soil Research ◽  
2008 ◽  
Vol 46 (1) ◽  
pp. 37 ◽  
Author(s):  
M. R. Sargeant ◽  
C. Tang ◽  
P. W. G. Sale
Keyword(s):  
Electrical Conductivity ◽  
Hydraulic Conductivity ◽  
Physical Properties ◽  
Soil Nitrogen ◽  
Fold Increase ◽  
Dry Weight ◽  
Saturated Hydraulic Conductivity ◽  
Distichlis Spicata ◽  
Discharge Zone ◽  
Spatial And Temporal Variation

Landholder observations indicate that the growth of Distichlis spicata in saline discharge sites improves the soil condition. An extensive soil sampling survey was conducted at the Wickepin field site in Western Australia, where D. spicata had been growing for 8 years, to test the hypothesis that this halophytic grass will make improvements in chemical and physical properties of the soil. Soil measurements included saturated hydraulic conductivity, water-stable aggregates, root length and dry weight, electrical conductivity, pH, and soil nitrogen and carbon. Results confirm that marked differences in soil properties occurred under D. spicata. For example, a 12-fold increase in saturated hydraulic conductivity occurred where D. spicata had been growing for 8 years, compared to adjacent control soil where no grass had been growing. There were also improvements in aggregate stability, with the most notable improvements in the top 0.10 m of soil, again with the greatest improvements occurring where 8 years of growth had occurred. Soil nitrogen and carbon increased under the sward, with the biggest increases occurring in the top 0.10 m of soil. Electrical conductivity measurements were more variable, mostly due to the large spatial and temporal variation encountered. However, the findings generally support the proposition that the growth of D. spicata does not lead to an accumulation of salt within the rooting zone.

Towards a more rational approach to chemical compatibility testing of clay

2002 ◽  
Vol 39 (3) ◽  
pp. 597-607 ◽  
Author(s):  
J K Kodikara ◽  
F Rahman ◽  
S L Barbour
Keyword(s):  
Boundary Condition ◽  
Hydraulic Conductivity ◽  
Rigid Wall ◽  
New Technique ◽  
Rational Approach ◽  
Lateral Strain ◽  
Test Results ◽  
Chemical Compatibility ◽  
Test Technique ◽  
Flexible Wall

Chemical compatibility tests using hydraulic conductivity testing with chemical permeants are normally undertaken to assess the integrity of compacted clayey liners used for waste containment. This paper highlights the fact that current routine methods of flexible wall and rigid wall testing techniques fail to represent the zero lateral strain boundary condition that is required to realistically represent the field situation. The test results indicate that flexible wall permeameters underestimate the likely increases in hydraulic conductivity due to chemicals, while the rigid wall permeameters can severely overestimate these effects. A new test technique, which incorporates the zero lateral strain condition in a simple manner, is presented. This technique involves the use of a rigid wall concept in a flexible wall permeameter. A split rigid mould is used to encase the soil specimen that is glued to the internal surfaces of the mould, to apply the zero lateral strain boundary condition. The new technique is shown to be suitable for both chemical compatibility and desiccation testing. The tests were undertaken with varying concentrations of saline water, methanol, and landfill leachate. The test results indicate that the new technique produces results that fall between the results obtained from flexible wall and rigid wall permeameters. It is argued that the new test technique provides a more rational approach for chemical compatibility testing than the current rigid wall and flexible wall techniques.Key words: soil, hydraulic conductivity, chemical compatibility, landfill, permeameter, boundary condition.

Compressibility and hydraulic conductivity of a chemically treated expansive clay

2001 ◽  
Vol 38 (1) ◽  
pp. 154-160 ◽  
Author(s):  
Zalihe Nalbantoglu ◽  
Erdil Riza Tuncer
Keyword(s):  
Fly Ash ◽  
Hydraulic Conductivity ◽  
Expansive Soil ◽  
Dry Weight ◽  
Pozzolanic Reaction ◽  
Exchange Capacity ◽  
Expansive Clay ◽  
Preconsolidation Pressure ◽  
Few Data ◽  
Published Research

The paper presents a series of laboratory tests and evaluates the effect of lime and fly ash on the compressibility and hydraulic characteristics of an expansive soil in Cyprus. The tests were performed at different percentages of lime (0–7%) and fly ash (15 and 25%) by dry weight of soil, and additional tests were also performed on soils treated with 15% fly ash plus 3% lime. Previously published research reveals that few data are available concerning the compressibility and hydraulic conductivity of lime-treated soils. The results of this study indicate an increase in the vertical effective yield stress (apparent preconsolidation pressure) and a decrease in the compressibility characteristics of the treated soils. Moreover, unlike some of the findings in the literature, higher hydraulic conductivity values were obtained with time. This finding has been substantiated by the reduced cation exchange capacity (CEC) values, which indicate that the pozzolanic reaction causes the soils to become more granular in nature, resulting in higher hydraulic conductivity.Key words: cementation, compressibility, fly ash, hydraulic conductivity, lime.

Weathering-induced fissuring and hydraulic conductivity in a natural plastic clay

1998 ◽  
Vol 35 (6) ◽  
pp. 1101-1108 ◽  
Author(s):  
K Yuen ◽  
J Graham ◽  
P Janzen
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Aggregates ◽  
Triaxial Tests ◽  
Natural Clay ◽  
Plastic Clay ◽  
Order Of Magnitude ◽  
Confining Pressures ◽  
Flexible Wall ◽  
High Plastic

Flexible-wall (triaxial) permeability tests have examined how laboratory-induced weathering affects the hydraulic conductivities of "undisturbed" specimens of a high-plastic expansive natural clay. After freezing-thawing or drying-wetting, hydraulic conductivities were on average about one order of magnitude higher than unweathered values. Reductions of hydraulic conductivity occurred in some specimens that were dried and then rewetted before permeation. The generally small changes in hydraulic conductivity are attributed to the expansive nature of the clay which allows swelling and reorientation of soil aggregates on thawing or rewetting. The changes may also have been influenced by the confining pressures of 35 kPa used in the tests. Hydraulic conductivities measured by oedometer were smaller than those in triaxial tests and varied strongly with pressure level.Key words: hydraulic conductivity, clay, plastic, weathering, desiccation, freezing.

scholarly journals Blending Lime with Sugarcane Bagasse Ash for Stabilizing Expansive Clay Soils in Subgrade

2021 ◽  
Vol 53 (5) ◽  
pp. 210510
Author(s):  
Zalwango Teddy ◽  
Bazairwe Annette ◽  
Safiki Ainomugisha
Keyword(s):  
Sugarcane Bagasse ◽  
Expansive Soils ◽  
Construction Material ◽  
Dry Weight ◽  
Clay Soils ◽  
Dry Density ◽  
Expansive Clay ◽  
Maximum Dry Density ◽  
Slaked Lime ◽  
Sugarcane Bagasse Ash

Expansive soils constitute one of the most frequently encountered and challenging soils to geotechnical engineers. This study assessed the possibility of utilizing sugarcane bagasse ash (SCBA) by partially replacing slaked lime to stabilize expansive clay soils. The soil samples were picked from Muduuma area, Mpigi district, Central Uganda. Experimental tests of linear shrinkage (LS), plasticity index (PI), and California Bearing Ratio (CBR) were conducted on both unstabilized soil and SCBA-lime treated samples. The SCBA-lime mixture was prepared by partially replacing 5% lime with SCBA at 2, 4, 6, 8, and 10% by weight. Hence, SCBA was used in proportions of 0.1, 0.2, 0.3, 0.4, and 0.5% by dry weight of the soil. The addition of lime greatly lowered the PI and LS, which later increased with the addition of the SCBA. The maximum dry density was generally lowered with the addition of lime and SCBA, from 1.87 g/cm3 to 1.58%. The CBR increased with SCBA-lime addition from 12% for unstabilized soil up to 48% at 6% SCBA replacement. The optimum lime replacement was established as 6% SCBA lime replacement based on CBR criteria. At the 6% optimum, the optimum moisture content (OMC) was 1.7 Mg/m3, LS was 10%, and PI was 20%. This study demonstrated the potentiality of SCBA as a novel construction material, specifically by partially reducing the usage of the unsustainable, non-environmentally friendly lime. It is also expected to enable using currently unsuitable clays from the region.

scholarly journals Physical Properties of Sandy Soil Affected by Soil Conditioner Under Wetting and Drying cycles

1998 ◽  
Vol 3 (2) ◽  
pp. 69 ◽  
Author(s):  
M.I. Choudhary ◽  
A.M. AI-Omran ◽  
A.A. Shalaby
Keyword(s):  
Hydraulic Conductivity ◽  
Physical Properties ◽  
Bulk Density ◽  
Sandy Soil ◽  
Dry Weight ◽  
Saturated Hydraulic Conductivity ◽  
Wetting And Drying ◽  
Soil Conditioner ◽  
Wetting And Drying Cycles ◽  
Unsaturated Hydraulic Conductivity

Information on the effectiveness of soil conditioners over a prolonged period is scarce. A laboratory experiment was undertaken to evaluate the effectiveness of a polyacrylamide (Broadleaf P4) soil conditioner on the physical properties of sandy soil subjected to wetting and drying cycles. Four concentrations of Broadleaf P4 0, 0.2, 0.4, and 0.6% on dry weight basis were uniformly mixed with a calcareous sandy soil. Addition of Broadleaf P4 to sandy soil increased the water holding capacity, decreased the bulk density, and increased the porosity and void ratio at 0 and 16 wetting and drying cycles. The coefficient of linear extensibility increased considerably with increasing concentrations of the polymer. The addition of polymer at 0 and 16 cycles increased considerably the retention and availability of water in sandy soil. Saturated hydraulic conductivity decreased with increasing concentrations of Broadleaf P4 whereas unsaturated hydraulic conductivity at 0 and 16 cycles showed an increase with increasing soil moisture contents. After I6 wetting and drying cycles, the capacity of the soil to hold water was lost on average by 15.8% when compared to the 0 wetting and drying cycle. The effectiveness of the soil conditioner on bulk density, coefficient of linear extensibility, available water and saturated hydraulic conductivity was reduced on average by 14.1, 24.5, 21.l and 53.7% respectively. The significant changes in soil properties between 0 and 16 cycles suggested that the effectiveness of the conditioner decreased with the application of wetting and drying cycles. However, its effect was still considerable when compared to untreated soil under laboratory conditions.

scholarly journals Assessment of Pedotransfer Functions for Saturated Hydraulic Conductivity of Anatolian Soils

2020 ◽  
Vol 8 (5) ◽  
pp. 1188-1194
Author(s):  
Gülay Karahan
Keyword(s):  
Hydraulic Conductivity ◽  
Input Data ◽  
Mean Squared Error ◽  
Organic Matter Content ◽  
Matter Content ◽  
Saturated Hydraulic Conductivity ◽  
Morphological Properties ◽  
Pedotransfer Functions ◽  
Coefficient Of Determination ◽  
Alkaline Soils

Hydraulic conductivity is an essential base for applied research in soil and water management, landscape, and environmental disciplines. Saturated hydraulic conductivity (Ksat) is one of the most important soil physical properties, which is considered in the planning of irrigation and drainage and predicting other soil hydrological processes. However, it has been frequently reported that measurement of Ksat is laborious, time-consuming, and expensive due to its high spatial variability and this has motivated researchers to develop indirect methods such as pedotransfer functions (PTFs) for developing Ksat-database in regional and national scales. In this study, eight Ksat studies with the PTFs in Anatolian soils were reviewed. PTFs were evaluated regarding their type, predictors used, and their performance. The majority of studied PTFs were developed on alluvial, colluvial, and alkaline soils in semi-arid and semi-humid climates. Multiple linear regression (MLR) and artificial neural networks (ANNs) have been common PTFs, and soil texture, bulk density, organic matter content, and pH have been common predictors used with these PTFs. Root mean squared error (RMSE), mean absolute error (MAE), and coefficient of determination (R2) were the commonly used criteria in the verification and validation of the PTFs. Studies on the use of Ksat and PTFs are inadequate, and researches are still needed to be able to use it nationwide and can develop an adequate database. According to the results of PTF studies, the highest R2 and correlation coefficient (r) values belong to the Rosetta and MLR types of the PTFs, respectively. The lowest RMSE value was obtained with the equations in which the physical and chemical soil properties were used together as input data for PTFs. In addition, it has been noted that the soil morphological properties should be used as input data in PTFs studies, especially in Ksat estimation.

Evaluation of the Curing Time Effect on the Swelling, Unconfined Strength and Resilient Modulus of an Expansive Soil Improved with Hydrated Lime

2021 ◽  
pp. 036119812110570
Author(s):  
İ. Süt Ünver ◽  
M. A. Lav ◽  
E. Çokça ◽  
G. Baykal
Keyword(s):  
Resilient Modulus ◽  
Expansive Soils ◽  
Dry Weight ◽  
Soil Samples ◽  
Natural Soil ◽  
High Plasticity ◽  
Expansive Clay ◽  
Curing Time ◽  
Clay Deposits ◽  
Swell Potential

Soils with high plasticity and high swell potential undergo great volume changes in the presence of unstable water content changes. The resulting expansion leads to damage to pavements and/or lightweight structures with such a subsoil. Expansive soils can be improved by adding chemical stabilizers such as lime, fly ash and micro cement. To construct a highway on an expansive subgrade soil, the subgrade should be stabilized to satisfy the minimum requirements of the highway standards. In this research, expansive clay samples were collected from clay deposits in the Akyurt district of Ankara (Turkey), near Esenboğa Airport. The swelling, strength and resilient modulus properties of the soil samples were determined via laboratory tests. First, reference tests were carried out on natural soil samples. Then, the clay samples were mixed with lime agent at different percentages (1%, 3%, 5%, 7% and 9%) according to the dry weight of the soil. The index, swelling, strength and resilient modulus (Mr) properties of these samples were determined. The soil samples were tested at 7, 28, 56 and 90-day curing times for each percentage of lime agent considered. The changes in the abovementioned properties, especially with regard to the effect of curing time on improvement, were interpreted in this research. Designing for a 7% lime content and a 28-day curing time can be a sound solution for addressing the expansive clay studied in this research, since the criteria of the Turkish Highway Standards are satisfied under these conditions.

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