Clayey Soil Samples Research Articles

Utilizing Magnesium Carbonate Induced by CO2 to Modify the Performance of Plastic Clay

Highly plastic clays pose significant challenges in engineering projects. Various techniques have been employed to enhance their properties, though many face difficulties related to implementation and environmental impact. This study examines the effect of CO2-induced magnesium carbonate on improving the geotechnical behavior of plastic clay. CO2-induced magnesium carbonate was produced via mineral carbonation and used to improve the behavior of highly plastic natural clay. CO2 gas was injected into a sodium hydroxide solution to produce carbonate ions (CO32−). Magnesium carbonate was precipitated on a laboratory scale by adding magnesium sulfate solution to the carbonate ion solution. Clayey soil samples were obtained from test pits in the Meyghan Plain near Arak, Iran. The clay samples were treated with different percentages of the produced magnesium carbonate. Various parameters of the treated and untreated samples, including index properties, unconfined compressive strength, consolidation behavior, and swelling potential, were studied. It was found that the liquid limit and plasticity index of the treated clay decreased as the magnesium carbonate content increased. The soil classification changed from high plastic clay (CH) to low plastic silt (ML) with the addition of 15% magnesium carbonate to the highly plastic clay. The unconfined compressive strength of the treated clay increased. Additionally, the consolidation behavior and swelling index of the treated clay improved as the magnesium carbonate content increased. This study confirms that CO2-induced magnesium carbonate is a promising material for improving the behavior of highly plastic clays, offering a sustainable approach to environmental management.

Evaluation of the Permeability of Clay-Lime Mixtures for Hazardous Waste Insulation Barriers, Case of Southern Algeria (Adrar)

Containment of hazardous waste is one of the methods that can be used today for its disposal worldwide, especially in landfills. In order to preserve groundwater, landfills are constructed on a natural or reconstituted clay layer of low permeability, known as a passive safety barrier. This paper presents an experimental laboratory study that aims to upgrade local materials for use as a passive barrier in the bottoms of hazardous waste storage facilities (HWSCs). The basic materials are clays from the Adrar region in southern Algeria. An experimental study based on physical-chemical characterization and mechanical tests was performed on 2 samples of clayey soils (AA, Adrar clay, and AB, Bouda clay). Physico-chemical and mechanical characterization of Adrar clay (AA) mixtures with lime was conducted to minimize swelling and improve the studied soil. The permeability criterion allowed the adoption of an optimal mixture of Adrar clay + 6 % lime for a permeability lower than 10–12 m/s. HIGHLIGHTS Ideal solution to protect natural groundwater resources using local materials, clay and lime Large area exceeding 30 km2 of clay sources and including sources of oil pollution Noticeable improvement in clay properties thanks to the addition of lime to reduce swelling The treated clay has a very low permeability value, lower than 10−12 m/s and is ideal for hazardous waste storage centers GRAPHICAL ABSTRACT

Boosting-based ensemble machine learning models for predicting unconfined compressive strength of geopolymer stabilized clayey soil

The present research employs new boosting-based ensemble machine learning models i.e., gradient boosting (GB) and adaptive boosting (AdaBoost) to predict the unconfined compressive strength (UCS) of geopolymer stabilized clayey soil. The GB and AdaBoost models were developed and validated using 270 clayey soil samples stabilized with geopolymer, with ground-granulated blast-furnace slag and fly ash as source materials and sodium hydroxide solution as alkali activator. The database was randomly divided into training (80%) and testing (20%) sets for model development and validation. Several performance metrics, including coefficient of determination (R2), mean absolute error (MAE), root mean square error (RMSE), and mean squared error (MSE), were utilized to assess the accuracy and reliability of the developed models. The statistical results of this research showed that the GB and AdaBoost are reliable models based on the obtained values of R2 (= 0.980, 0.975), MAE (= 0.585, 0.655), RMSE (= 0.969, 1.088), and MSE (= 0.940, 1.185) for the testing dataset, respectively compared to the widely used artificial neural network, random forest, extreme gradient boosting, multivariable regression, and multi-gen genetic programming based models. Furthermore, the sensitivity analysis result shows that ground-granulated blast-furnace slag content was the key parameter affecting the UCS.

The Unconfined Compressive Strength of Hy-drated Lime Stabilized Clayey Soil at Different Water Contents and Different Curing Times

This research was done to find out how adding hydrated lime and extra water content to clayey soil samples affecting their unconfined compressive strength (UCS). The clayey soil is a locally available soil from the clayey soil area in Cyrene, northeastern of Libya. In the soil samples, hydrated lime (HL) was added at a rate of 5% of the dry weight of the soil. The standard compaction test was conducted on the untreated natural soil sample “NS” so that the optimum water content at the maximum dry density can be determined wop1. Because of the addition of hydrated lime to the soil will affect the dry density-water content relationship, the standard compaction test was conducted again on the treated soil sample “NS+5%HL” to determine another optimum water content wop2. These optimum water values {wop1 =17.8 & wop2=19.5} will be used to prepare unconfined compressive strength specimens. In the experimental work two soil mixtures will be used beside the natural soil mixture. The first mixture "NS+5%HL+wop1" and the second mixture "NS+5%HL+wop2" were prepared in addition to the natural soil mixture "NS+wop1". All unconfined compressive strength specimens for the first and second mixtures were extracted and tested at 7 and 14 days of curing, then comparison were made. The first mixture, "NS+5%HL+wop1" will be compared with the natural soil mixture, "NS+ wop1" in order to understand the impact of HL addition. The effect of the water content changing can be seen when the second mixture, "NS+5%HL+wop2" is compared with the first mixture, NS+5%HL+wop1. According to the findings, Although the first mixture’s specimens have the least dry density value, the UCS values increased by 218.5 and 386.5% at 7 and 14 days of curing, respectively, when compared to the natural soil mixture. This illustrates the result of the added hydrated lime. At curing times of 7 and 14 days, respectively, the UCS values for the second mixture fell by 8.61 and 14.11% when compared to the first mixture. And this illustrates the impact of variations in water content.

Influence of remediation by electrokinetic on the chemical and geotechnical properties of clayey soil contaminated by copper sulfate

The enhanced electrokinetic (EK) technique is an innovative approach and increasingly used in remediation of the fine-grained texture soils contaminated with different types of contaminant. In this study, the EK is enhanced by adding an intermediate compartment and using purging solutions at the electrode’s compartments. The natural clayey soil samples were obtained from Al-Ahadab oil field and artificially contaminated with two ratios of copper sulfate (66666.67 and 26666.67 mg/kg). The feasibility of using EK technique was evaluated by the efficiency of extracting copper from soil and the magnitude of recovery in the geotechnical properties of soil. The duration of remediation was continued for about 240-250 hours depending either on the continuity of electroosmosis flow or reach a constant rate of electrical current. The removal efficiency of copper from contaminated soil samples was ranged from 98.4% to 99.6%. The EK remediation technique proved a marginal impact on the specific gravity and Atterberg’s limits, but it has a significant effect on the shear strength parameters and compressibility of soil. Furthermore, the EK technique can be considered an efficient method for removing the low and high concentrations of copper sulfate from clayey soil of low permeability.

Nonlinear modeling of carbon dynamics in soil treated with tannery sludge

In 2020, the Brazilian commercial cattle herd was the largest in the world, representing 14.3% of the worldwide herd, with201.7 million heads. Although this activity yields significant profits, contributing to the economic and social development ofBrazil, it has been the target of concerns, mainly due to the large production of waste/effluents associated to bovine leatherprocessing. In this scenario, mineralization is important because nutrients essential for plant growth are released duringthe process of organic waste decomposition, and the dynamics of carbon release can be described by nonlinear regressionmodels. Thus, this study aimed to model the mineralization of organic carbon in the soil for 6, 12, 24, and 36 megagramsdoses per hectare (Mg ha−1) of tannery sludge using the Stanford & Smith, Cabrera, and Juma nonlinear models. Very clayeysoil samples were used: eutroferric red nitosol (NVef). Mineralized carbon was measured in 21 observations over time untilthe 105th day of incubation. Parameters were estimated using the least squares method. Adjustments were compared usingthe corrected Akaike information criterion (AICc) and the adjusted coefficient of determination (R2aj) as selection criteria. The Cabrera model had the best adjustments for doses 6, 12, and 24 Mg ha−1 and Juma for dose 36 Mg ha−1, based on the selection criteria used. Although the Stanford & Smith model is the most widely used in the literature to model soil carbon dynamics, its use was not the most appropriate for any of the doses evaluated in this study. The higher the dose of tannerysludge, the greater the amount of potentially mineralizable carbon.

Effect of freezing soil temperatures on strength parameters of clayey sand soils stabilized by poly propylene and poly vinyl alcohol fibers

Applying synthetic fibers is one of the most effective physical methods for soil improvement and stabilization. In this paper, we determine the effects of polypropylene (PP) and poly vinyl alcohol (PVA) fibers contents (0.2, 0.5, 1.0 and 1.5%) at environment temperature (25 °C) and various freezing soil temperatures (0, −5, −10 and − 15 °C) on stabilization of the clayey sand soil (SC) samples. The results show that for both types of fibers, by simultaneous increasing of fiber content and lowering the temperature, the values of the unconfined compressive strength (UCS), elastic modulus (EM), ductility and California bearing ratio (CBR) increase, and they all reach their maximum values for 1.5% fiber content at −15 °C. Moreover, we show that PVA fibers perform better compared to PP fibers in increasing of UCS, EM, ductility and CBR values for different fiber contents and temperatures. This can be attributed to the fact that PVA has higher tensile and flexural strength compared to PP fiber.

The Role of Wastewater in Controlling Fluvial Erosion Processes on Clayey Bedrock

In recent decades, fluvial erosion processes in highly anthropized areas are mainly associated with in-stream gravel mining activities or with the presence of artificial reservoirs which have increased the erosive capacity of the river as a consequence of the reduced sediment transport or the modification of the longitudinal profile of the channel. On the other hand, the role of pollutants in the degradation processes of soils with a predominantly clayey component is little known. The present study, through chemical analyses of water and mineralogical–geotechnical analyses of clayey soil samples taken along some river channels in central Italy in correspondence with water treatment plants, highlights how “polluting” elements present in the water can modify the crystalline lattice and consequently, the resistance parameters of the soil itself, making it more susceptible to erosion processes. In particular, significant are the variations of the Plasticity Index, which tends to double in all the samples and the transformations of clayey minerals such as illite and kaolinite, toward montmorillonite and smectite, with consequent breaking of the ionic bonds and decrease of the material cohesion. Although in the cases studied this phenomenon was quantitatively less relevant than the “mechanical” processes described above, it could have a greater impact in the presence of landfills or large production settlements (agricultural or industrial) where the concentration of pollutants can be substantial.

Random Forest Algorithm for the Strength Prediction of Geopolymer Stabilized Clayey Soil

Unconfined compressive strength (UCS) can be used to assess the applicability of geopolymer binders as ecologically friendly materials for geotechnical projects. Furthermore, soft computing technologies are necessary since experimental research is often challenging, expensive, and time-consuming. This article discusses the feasibility and the performance required to predict UCS using a Random Forest (RF) algorithm. The alkali activator studied was sodium hydroxide solution, and the considered geopolymer source material was ground-granulated blast-furnace slag and fly ash. A database with 283 clayey soil samples stabilized with geopolymer was considered to determine the UCS. The database was split into two sections for the development of the RF model: the training data set (80%) and the testing data set (20%). Several measures, including coefficient of determination (R), mean absolute error (MAE), and root mean square error (RMSE), were used to assess the effectiveness of the RF model. The statistical findings of this study demonstrated that the RF is a reliable model for predicting the UCS value of geopolymer-stabilized clayey soil. Furthermore, based on the obtained values of RMSE = 0.9815 and R2 = 0.9757 for the testing set, respectively, the RF approach showed to provide excellent results for predicting unknown data within the ranges of examined parameters. Finally, the SHapley Additive exPlanations (SHAP) analysis was implemented to identify the most influential inputs and to quantify their behavior of input variables on the UCS.

Optimization and Validation of the Miniaturized Solid-Liquid Extraction with Low Temperature Purification (SLE-LTP) Method for Determining Fluopyram in Sandy, Clayey and Medium-Textured Soil

Fluopyram is a fungicide which can also be used as a nematicide in agricultural areas. The Brazilian Ministry of Agriculture authorized the commercialization and use of this molecule in Brazilian agriculture in 2019, but studies involving the development of an extraction and quantification method of this compound in environmental matrices such as soil are still scarce. Therefore, the present study aimed to optimize and validate the miniaturized version of the solid-liquid extraction with low temperature purification (SLE-LTP) method for determining this compound in sandy, clayey and medium-textured soil samples. All analyzes in this study were performed by gas chromatography coupled to mass spectrometry (GC-MS). The results revealed that the analyte recovery percentages in the three soil types ranged from 86 to 114% with a relative standard deviation of less than 15%. In addition to employing smaller amounts of reagents and sample, the miniaturized SLE-LTP method was selective, precise, exact, and linear in the range from 3 to 210 μg kg-1, and reached a limit of quantification lower than 3.00 μg kg-1 for the three soil types. The extraction method was applied to 30 real samples collected in coffee growing regions, but no residue of this compound was detected in these samples.

Effect of Emulsified Asphalt on Expansive Soil Strength and Swelling

Some clay soils classified as extended soils threaten the structures resting on them. Many additives are available to improve the properties of expanded soils. This study tries to investigate the consequences of wetting-drying cycles on the swelling behavior of modified expansive clayey soils under laboratory conditions by modifying expansive clayey soil samples using emulsified asphalt. Five different percentages of emulsified asphalt were used: (2, 4, 6, 8, and 10) %. The natural and treatment soils were tested for classification, specific gravity, compaction characteristics, free swell and swell pressure, consolidation, and compressive strength. The liquid limit and plasticity index have been lowered by adding Emulsified Asphalt. After that, the effects of Emulsified Asphalt on undrained shear strength characteristics (cohesion and friction angle) have been studied. The results revealed that when the emulsified asphalt content was increased to 10%, the swelling pressure and swelling potential decreased by 58 and 78 %, respectively. The swell and shrink improvement factor for the 10% emulsified asphalt addition is always larger than 75%. As the duration of wetting-drying cycles increased, the swelling pressure and swelling potential values were also reduced. The plastic limit, on the other hand, increased as the Emulsified Asphalt content increased. Increasing the amount of Emulsified Asphalt increased the maximum dry unit weight values, whereas the optimum water contents increased. It was concluded that emulsified asphalt stabilization may be useful for expansive clay as it improves compressive shear strength.

Compaction Curves and Strength of Clayey Soil Modified with Micro and Nano Silica.

Some Clayey soils are generally categorized as weak soils, and structures lying on such soils have been exposed to severe damage. Therefore, the central thesis of this paper is the impact of a waste material known as a silica fume as nano and micro material on soil’s behaviour. To evaluate the effects of those additives on Atterberg limits, compaction characteristics and unconfined compressive strength, clayey soil samples have been transformed using micro and nano silica fume (by-product materials). In the current investigation, silica fume is used at four different percentages: 0, 2, 4, and 7%. The results show that the plasticity index of soil decreases with the addition of micro silica and increases with the addition of nano-silica. Increasing nano silica percentage improves the dry density of the compacted soil and reduces the optimum moisture content. An opposite behavior is observed with adding micro silica to compacted soil. Finally, 4% of silica fume is found to be the optimum dosage to improve the unconfined compressive strength of the treated soil with both additives. As a result, treating the weak clay soil with micro and/or nano-silica fume has the potential to be impactful.

Mobility of organotin pesticides: azocyclotin and cyhexatin in clayey and sandy soils from the Northern Paraná state—Brazil

Azocyclotin and cyhexatin are pesticides commonly used in mite control. However, these organotin compounds (OTC) are highly harmful to the aquatic ecosystem and supposedly mobile in the soil. In addition to not existing defined rules of use, few studies have been carried out on organotins’ behavior and environmental control. Liquid chromatography has been pointed out for the OTC quantitation because of gas chromatography’s thermal stability and derivatization limitations. Hence, a new high-performance liquid chromatography method with photodiode array detection was developed for quality assurance and quality control and environmental performance assessment purposes. Hysteresis index (HI) and mobilization factor were determined from sorption/desorption in sandy and clayey soils to assess mobility and environmental risk. Mobilization was observed for the two compounds by applying the dual-mode Freundlich–Langmuir model to the isotherms. Azocyclotin showed greater mobility, 23% and 19%, and HI of − 0.15 and 7.8 \(\times \) 10\(^{-4}\) for clayey and sandy soil samples, respectively. Although cyhexatin was practically immobile for both soil samples, it can be mobilized as an azocyclotin metabolite, increasing the environmental impact and risk for agricultural uses.

Surface treatment of clayey soil particles for reducing water loss through evaporation

To conserve water in crop production and landscaping, plastic mulch or sheets are commonly used. However, the environmental impact of plastic waste is a concern. Therefore, herein we report that a silane coupling agents-based coating can be applied to natural clayey soil samples to suppress water evaporation. The hydrophobicity of soils (particle sizes 200–500 µm) can be enhanced. Evaporation flux was investigated using an electronic balance placed inside a chamber by maintaining constant flow, temperature, and relative humidity. The magnitude of evaporation flux was adjusted by placing a hydrophobic-treated soil layer in the system. It is clear that the hydrophobic-treated soil particle layer interacts with water capillaries to reduce the evaporation flux, but the effect on water vapor diffusion was small.

Cracking of unsaturated clays using a newly developed small-beam bending apparatus and analysis by digital image correlation

This research presents a comprehensive investigation on the impact of initial imposed suction both on the applied tensile force and the cracking phenomenon of unsaturated clayey soil samples. The proposed experimental approach is based on using a new developed apparatus for testing the indirect tensile force on small-beam bending. Several sets of bending tests have been carried out on small clay beams initially submitted to different levels of suction (361 MPa, 110 MPa and 38 MPa). The approach consisted first to study the global behaviour by estimating the maximum tensile force Fmax which controls the initiation of tensile cracks. The results show that Fmax varies with the initial imposed suction level as well as the consolidation stress direction representing the initial loading applied to the sample during the stage of clay core preparation. Then, unload–reload cycles allowed to describe the reversibility of beam’s behaviour versus the initial imposed suction. Finally, by using digital image correlation technique, the formation and propagation of cracks were precisely captured through the measurement of the local strain variations, especially close the crack tip.

Data based model development on swelling characteristics of expansive earth material from selected sites under West Bengal region in India

This investigation was carried out to study the swelling characteristics of remolded expansive black cotton soil with apparent self-organizing characteristics from selected sites located at region under Eastern India. Swelling potentials and swelling pressures for natural soils and their sand admixtures under varying conditions have been measured. An attempt has been made to predict the swelling potential from plasticity index and clay content of soil. In this study the remolded sample prepared from clayey soil from Kolaghat, and expansive soil from Kharagpur local and Durgapur located in West Bengal state of India were tested. The remolded soil sample passing through 4.75 mm were used. Fine sands passing sieve size 0.6 mm and retained on 0.075 mm added in different proportions to change the clay content of the soils. Fine sands were added at the rate of 5% and 10% by wt. to all the samples. Soil tests, such as Grain Size Distribution, Atterberg Consistency Limits, Compaction tests, Swelling Pressure Tests, Consolidation Tests, Swelling Potential Tests and Free Swell Tests were performed. An attempt was made to develop relationship among clay-content, activity of the clay characteristics, and the percentage of swell and plasticity index to predict probable swelling potential of clayey soil samples. A consistent functional correlation with realistic parametric assessment was observed amongst Atterberg limits and free-swell tests and facilitated a reasonably realistic assessment of swelling capacity of given expansive soils.

A study on radiation shielding potentials of green and red clayey soils in Turkey reinforced with marble dust and waste tire

The increasing radiation applications in our daily life makes it essential to protect ourselves from the harms of radiation by using alternative, cheap and natural materials. The present study aimed to analyze the radiation shielding abilities of green and red clayey soils from Oltu/Erzurum in Turkey, reinforced with waste tires and marble dust. For the purpose to investigate the shielding features of the samples, radiation attenuation parameters were determined by using EpiXS software, which can calculate partial or total cross-sections, partial or total mass attenuation coefficients, electron densities, effective atomic numbers, and buildup factors for energy absorption and exposure between 1keV and 1GeV. We compared the obtained mass attenuation coefficients and total atomic cross-section values of the samples with those of a widely used shielding material, ordinary concrete, to make a meaningful evaluation about the shielding potentials of the samples. To validate obtained values by EpiXS, we also calculated the mass attenuation coefficients of the samples by XCOM code, and compatible results were obtained. Among all the studied clayey soil samples, green clay reinforced with marble dust and waste tire has the highest shielding capability. It can also be mentioned that reinforcement with marble dust and waste tire improves the shielding ability of the clayey soils.

Strengthening Soft Clayey Subgrade Soil Layer Using Cement Kiln Dust and Palm Kernel Ash Materials

The product materials which are generated from industrial manufacturing are used to enhance the engineering and chemical properties of soil. There are three phases of soil improvement are improvement without the addition of any other material, adding certain materials, and providing reinforcement. This study used materials product from industrial and waste materials as additives to improve the physical properties and strength of clayey soil subgrade under foundation and flexible pavement structure. This study has been investigated the effect of isolated and combined Cement Kiln Dust (CKD) and Palm Kernel Ash (PKA) materials on strength of clayey soil as tested by California Bearing Ratio (CBR) test. Various percentages of CKD and PKA materials were added to clayey soil samples to determine the optimum percent of CKD and PKA. The results showed that CKD and PKA have improved soil strength at the optimum compound percent of CKD content was 8% and PKA was 2% by weight of dry soil.

Bio-mediated method for improving surface erosion resistance of clayey soils

Soil surface erosion is a common natural phenomenon, considerably leading to land degeneration and environment deterioration. In this study, microbially induced calcium carbonate precipitation (MICP), a green and sustainable bio-mediated technique to stabilize soils, has been proposed as a promising solution to control surface erosion of the clayey soils. Clayey soil samples with different sand additions (0, 10, 20, 30, 40%, w/w) were used to construct slope models. Five groups of soil slope model samples were treated with MICP by the surface spraying method. Another group of samples treated with deionized water was also prepared for comparison. Subsequently, a series of simulated rainfall erosion tests were conducted on these models for which the dip angle is 45°. Results that include the erosion pattern, the weight and rate of the soil loss, and outflow properties revealed that the MICP treatment is effective for controlling the surface erosion of the clayey soils. The microstructural characteristics of the samples of the treated soils, obtained from the scanning electron microscopy (SEM) indicate that the improvement in the erosion resistance can primally be attributed to the protective dense surface crust, mainly calcium carbonate, that gets formed. This layer is responsible for the enhanced water stability and mechanical strength of the topsoil. It has also been observed that with an increase in the sand content added to the clayey soil, the effectiveness of MICP treatment on controlling soil erosion gets further enhanced due to an increased MICP treatment depth and a more stable soil microstructure.

Use of Triple-Exposure X-ray Computed Tomography for Nondestructive Identification of Heavy Elements in Soil Samples

ABSTRACT For the purpose of the nondestructive measurements of hazardous heavy-element-containing substances in soil samples, the emerging technique, triple-exposure X-ray computed tomography (CT), is proposed. The use of triple exposure (i.e. three different acceleration voltages for the X-ray tube) improves the accuracy of the identification of the atomic number of a heavy element. With lead as the target element, virtual X-ray microtomography simulations utilizing a polychromatic X-ray source accelerated at 70, 100, and 140 kV were performed. CT images for the three voltages were reconstructed on a computer for clayey soil samples with heavy-element-containing natural minerals, namely galena (PbS), witherite (BaCO3), stibnite (Sb2S3), sphalerite (ZnS), and magnetite (Fe3O4). Quantitative analysis of the reconstructed CT images was performed to obtain the following results. (i) Galena can be distinguished from other heavy minerals (i.e. witherite, stibnite, sphalerite, and magnetite). (ii) The lead content in the clayey soil can be estimated with reasonable accuracy. These successful results demonstrate that the triple-exposure CT technique is promising for the nondestructive characterization of soil samples contaminated with hazardous heavy elements such as lead.