Search

This study uses fly-ash-based superplasticized geopolymer by adding a naphthalene-centered superplasticizer to the geopolymerized soil. Alkali-binder ratios and alkali-activator ratios are varied simultaneously with a molarity of 10M. The optimum dosages of binder, geopolymer, and superplasticized geopolymer are found from unconfined compression tests. California Bearing Ratio (CBR), pH, consolidation, water-holding capacity, and microstructure tests were performed on optimum dosages. The clayey soil's undrained shear strength and CBR value increased as the geopolymer was superplasticized. The 28-day undrained shear strength of geopolymerized clay was around 300 kPa, attained within three days of the curing period with superplasticized geopolymer. This is because adding a superplasticizer increases the polymerization reaction rate and improves the geopolymer's performance. The maximum undrained shear strength was attained within seven days of the curing period for both cases. The undrained shear strength after a curing period of 7, 14, and 28 days for geopolymer and superplasticized geopolymer was found to be almost the same value, which shows that after seven days, curing has little role in strength improvement. The hydraulic conductivity and coefficient of consolidation of geopolymerized soil increased with the addition of superplasticizer due to the reduction in fine particles and plasticity of the residual soil. Microstructural studies using scanning electron microscope and x-ray diffraction techniques showed an interaction between soil, geopolymer, and superplasticizer, thus confirming the formation of geopolymer gel and increased polymerization rate with the superplasticizer. [ABSTRACT FROM AUTHOR]

Electrical conductivity models have been widely used to estimate water content and petrophysical properties of soils in hydrogeophysical studies. However, these models are typically only valid for soils with non‐expandable matrices because they were originally developed for clean sandstone reservoir rocks. Soils containing swelling clays are characterized by matrices that expand/contract upon gaining/losing water. In this laboratory study, we demonstrate that soil matrix changes affect saturation estimation using Archie's laws. A sample of a soil containing a swelling clay was fully saturated with a potassium chloride solution, then left to dry evaporatively at room temperature for 8 days. The complex resistivity of the soil, along with its weight and volume shrinkage, were measured daily during the drying period, and the surface conductivity was calculated based on previous empirical findings. Over the course of the study, the simultaneous evaporation yielded a 33% decrease in volume and caused a nonlinear reduction in saturation with decreasing water content. Accounting for surface conductivity and correcting for saturation using the calculated volume reduction resulted in a power‐law relationship with high R2 values between resistivity and saturation along with reasonable saturation exponents. On the contrary, neglecting either surface conductivity or shrinkage caused similar underestimations of saturation exponents. These results indicate that the application of Archie's second law to soils with swelling clays leads to erroneous predictions of resistivity if saturation values are not corrected for changes in the volume of the soil and surface conductivity is neglected. Core Ideas: Soil shrinkage causes errors in Archie calculations.High surface conductivity of clays affects Archie calculations.Neglecting soil shrinkage causes underestimation of Archie's saturation exponent.Corrections for volume changes are required for Archie calculations in clayey soils.Corrected saturation results in better estimation of Archie's saturation exponent. [ABSTRACT FROM AUTHOR]

This research evaluates the performance of two low- and high-plasticity clays as the sole precursors to develop alkaline activation at ambient temperature. NaOH solutions with different concentrations of 2 to 10 mol/L along with binary solutions with NaAlO2/NaOH mass ratios of 1 and 0.75 for CL and CH clays, respectively, have been used as alkaline activators. Unconfined compressive strength (UCS), indirect tensile strength (ITS), ultrasonic pulse velocity (UPV) and Atterberg limits tests have all been conducted to thoroughly assess the geotechnical properties of alkali-activated clays. The experimental results show that CL with the best performance when mixed with 8 M NaOH activator renders higher mechanical strength and stiffness compared to CH showing a peak at 4 M NaOH. This observation is primarily attributed to the higher amorphous content and a weak interlayer force in CL that in turn contributes to more reactive silicate phases and gel products. Moreover, binary solution considerably enhances the mechanical performance of parent clays by modifying the Si/Al ratio in the mixture. Another important observation is the vulnerability of the alkali-activated clays to cracks and expansion due to alkali–silica reactions, leading to a significant drop in their mechanical strength and stiffness. Microstructural analyses also reveal the increase in amorphous content and the formation of flocculated particles covered by aluminosilicate gels, especially in CL-based samples where the layer-like structure of clay changes to sponge-like with globular units. More importantly, uncalcined clay-based samples are observed to be prone to the curing time-dependent cracking associated with expanding phases due to alkali–silica reactions or flocculated particles. These observations could be useful in geotechnical engineering practice for a variety of field applications in terms of both safety and performance because not only natural clays have been used as the sole precursors but also a relatively low alkali concentration has contributed to the optimum improvement of the composite material. [ABSTRACT FROM AUTHOR]

Offshore floating systems are held in position with chains that connect the floater to anchors embedded in the seabed. An essential component for calculating the overall mooring capacity is an accurate assessment of the holding resistance from the anchor chains. Existing studies generally simplify the (complex) chain geometry to that of a cylindrical bar, which does not account for the intricate geometry of the connected chain links. This paper reports on three-dimensional finite-element modeling that defined the capacity of a link of anchor chain in clay soil with consideration of the geometry of the chain links, including the influence from adjacent links. Both stud link and studless links were considered, along with the effect of embedment depth, link direction angle, and interface condition. The soil resistance acting on the chain links, represented by uniaxial bearing capacity factors Nn,max , Ns,max , and Nt,max along the normal, lateral, and axial directions of the chain link, respectively, were derived, and the soil failure mechanisms for these conditions are discussed. Equivalent bearing capacity factors Nq and Na were derived by converting the soil resistance to normal and tangential resistances (q and f) acting on an equivalent cylindrical bar. Ultimately, f/q was calculated to represent the friction coefficient, μ , which ranged from 0.2 to 0.4. [ABSTRACT FROM AUTHOR]

Clay soil processing using cement is widely done but it is difficult to find studies that fit this topic, because the case study conducted is on the famous transportation route, namely Jalan Kuta – Tanah Lot in Bali, Indonesia. Pavements at this location are often damaged. In the dry season the road here is often cracked, while in the rainy season there is a decrease in certain parts or potholes occur that endanger users. Therefore it is necessary to conduct an analysis. This research aims to obtain the right formula of the ideal mixture of cement and clay, through mechanical tests i.e. compressive strength. Some results that are in accordance with the research conducted have been contained in the literature review, especially density and compressive strength testing. The use of cement as a stabilizer in clay is successful, as well as for other types of soil. The method used is soil sampling directly at the site, then mixed cement with various variations (treatment). This study discusses the success of cement to stabilize clay soils, especially increasing compressive strength and decreasing plasticity index. According to the results obtained that using cement as a soil stabilizer shows significant strength results, especially in ideal mixtures. This research is believed to be able to answer the obstacles that exist in clay soils to function as sub grade. [ABSTRACT FROM AUTHOR]

Clay soil obtained from the Gwagwalada area of Abuja in the Northern part of Nigeria was obtained and used for this study to determine the suitability of water pH on soil strength for waste containment facilities such as landfills and surface impoundments. Water pH influences the strength and durability of soils employed in these facilities and the potential for chemical reactions that can damage containment barriers. An unconfined compressive strength test was conducted using British Standard Light (BSL) and British Standard Heavy (BSH) compaction at varying water pH (i.e., Acidic, Neutral, and Alkaline water) to see the effect it can have on the life span of the clay as a liner material. High-quality liner materials must meet the minimum unconfined compressive strength requirement of 200 kN/m². According to the test outcomes, when the amount of lime in the soil increased, especially at 4% content, the maximum dry density (MDD) increased to 1.81, 1.78, and 1.71 Mg/m³, and the optimum moisture content (OMC) decreased to 15.0,14.0, 16.0% for BSL compaction similar trend to BSH. The MDD is 1.93,1.83, 1.90 Mg/m³, and OMC is 13.2, 14.0, and 12.4% for BSH compaction for acidic, alkaline, and neutral water, respectively. The unconfined compressive strength (UCS) decreases as moulding water increases. The UCS values meet the 200 kN/m² minimum requirement for soils compacted with acidic and neutral pH water for all compaction efforts. When treated with neutral water, the recommendation of 4% lime addition compacted at BSH for liner material construction at -2%, 0, +2% OMC. It is also recommended that alkaline water is unsuitable for constructing liners because it reduces the strength of treated soil. [ABSTRACT FROM AUTHOR]

Freeze-thaw cycles significantly impact construction by altering soil properties and stability, which can lead to delays and increased costs. While soil-stabilizing additives are vital for addressing these issues, stabilized soils remain susceptible to volume changes and structural alterations, ultimately reducing their strength after repeated freeze-thaw cycles. This study aims to introduce a different approach by employing magnesium chloride (MgCl2) as an antifreeze and soil stabilizer additive to enhance the freeze-thaw resilience of clay soils. We investigated the efficiency of MgCl2 solutions at concentrations of 4%, 9%, and 14% on soil by conducting tests such as Atterberg limits, standard proctor compaction, unconfined compression, and freeze-thaw cycles under extreme cold conditions (−10 °C and −20 °C), alongside microstructural analysis with SEM, XRD, and FTIR. The results showed that MgCl2 reduces the soil's liquid limit and plasticity index while enhancing its compressive strength and durability. Specifically, soil treated with a 14% MgCl2 solution maintained its volume and strength at −20 °C, with similar positive outcomes observed for samples treated with 14% and 9% MgCl2 solutions at −10 °C. This underlines MgCl2's potential to enhance soil stability during initial stabilization and, most importantly, preserve it under cyclic freeze-thaw stresses, offering a solution to improve construction practices in cold environments. [ABSTRACT FROM AUTHOR]

There are three main electrochemical factors affecting the electroosmotic flow in clay soil: the voltage loss at the clay/electrode interface, the type of current carriers in the soil, and the ion composition change in the clay due to voltage application. Appropriate evaluation of these factors is important to cost effectively implement electroosmosis for in situ soil consolidation projects. In this study, three different experimental systems were developed and used to investigate electrochemical reactions occurring in reconstituted and natural marine clay during electroosmotic consolidation. The results of polarization tests show that the voltage loss at the clay/electrode interface is different depending on the combination of the clay material and electrode material. The results of electroosmotic element test also show that electroosmotic dehydration does not increase if large current–voltage value is applied and that an optimal current–voltage value for causing electroosmosis depends on the cohesive soil composition. If the clay contains a lot of oxidizable ions, such as sodium, these ions affect electrophoresis and chemical reactions that occur in the soil. Therefore, the optimal configuration to apply electric current also differs depending on the clay. The results of laboratory-scale electroosmotic dehydration tests, arranged in a realistic in situ layout, are performed to study the relationship between soil dehydration, consolidation, and surface crack generation. [ABSTRACT FROM AUTHOR]

Soft clay soil is known for low bearing capacity and is prone to soil collapse under shallow foundations through Local Shear Failure. An approach to enhance the load-bearing capacity of such soil is by adopting micro-piles as reinforcement. This study aims to determine the effectiveness of micro piles in strengthening shallow foundations on soft clay soil through laboratory-scale testing. The soft soil used comes from kaolin clay characterized by a cohesion (cu) of 20.692 kN/m² and water content (wc) of 58.631%. These properties guided the crafting of test specimens, formed with a diameter (ds) of 0.33m and a height (Hs) of 0.185m. Micropiles were constructed from bamboo with varying numbers (n = 4, 9, 16, 25), lengths (L1= 1.33B, L2= 1.73B, L3= 2.13B), and diameters (d1= 0.03B, d2 = 0.04B, d3= 0.07B). The shallow foundation model with a square shape of BxB (where B=0.075 m), incorporated diverse configurations for the installation of micro-piles (K1, K2, K3). The results showed that more micro-piles (n) led to a higher bearing capacity ratio at a 0.1B reduction (Rqult-mp). The most significant enhancements occurred with the longest micro-piles (L3 = 2.13B), the highest number (n4 = 25), and a diameter of 0.04 B. Additionally, configurations including micro-piles installed beneath and extending up to the foundation's edge (K1 and K2) exhibited significant enhancement in Rq0.1B for identical micro-piles numbers (n). The installation of micro-piles beyond the foundation perimeter did not yield substantial increases in Rq0.1B and, therefore, is not recommended. [ABSTRACT FROM AUTHOR]

Skirt–pile foundations have gained widespread attention in the field of offshore engineering due to their ease of installation and high bearing capacity. In this study, the ultimate bearing capacity, pile bending moment distribution and development, cumulative deformation characteristics, and cyclic stiffness development of skirt–pile foundations were investigated using physical model tests. The experimental results indicate that the ultimate bearing capacity and deformation resistance of the foundation can effectively be improved by increasing the skirt diameter. The cumulative deformation of the skirt–piles exhibited rapid development during the initial stages of cyclic loading, eventually stabilizing. Under long-term cyclic loading, the existence of the skirt can share the bending moment, which then affects the internal force distribution of the pile foundation along the axis. The pile foundation's cyclic stiffness reduces as the loading cycles increase and increases as the skirt diameter and length grow. Meanwhile, the horizontal cyclic stiffness decreases as the number of cycles increases, stabilizing after 3000 cycles. This study can not only deepen the understanding of the deformation laws of skirt–pile foundations in clay soil but also offers some references for the design of offshore pile foundations. [ABSTRACT FROM AUTHOR]

Clayey soils exhibit significant volumetric changes in response to variations in water content. The swelling pressure of clayey soils is a critical parameter for evaluating the stability and performance of structures built on them, facilitating the development of appropriate design methodologies and mitigation strategies to ensure their long-term integrity and safety. We present a dataset comprising maximum swelling pressure values from 759 compacted soil samples, compiled from 16 articles published between 1994 and 2022. The dataset is classified into two main groups: 463 samples of natural clays and 296 samples of bentonite and bentonite mixtures, providing data on various types of soils and their properties. Different swelling test methods, including zero swelling, swell consolidation, restrained swell, double oedometer, free swelling, constant volume oedometer, UPC isochoric cell, isochoric oedometer and consolidometer, were employed to measure the maximum swelling pressure. The comprehensive nature of the dataset enhances its applicability for geotechnical projects. The dataset is a valuable resource for understanding the complex interactions between soil properties and swelling behavior, contributing to advancements in soil mechanics and geotechnical engineering. [ABSTRACT FROM AUTHOR]

The theoretical and practical studies of the cyclic loads resulting from the movement and passage of trains on the unsaturated subgrade to determine the effect of the degree of saturation and moisture content on the foundations and infrastructure of the railway lines, especially the settlement in the railway lines as a result of the development of the train loads. Thirty-six laboratory experiments were carried out using models that simulate a railway with nearly half the scale of the real one, using an iron box of (1.5 × 1.0 × 1.0) meters and a layer of clay soil with a thickness of 0.5 m representing the base layer, were constructed inside it. Above it, there is a layer of crushed stone representing a 0.2 m thick ballast, topped by a rail line of 0.8 m long installed on three sleeper beams with dimensions of 0.9 m (0.1 × 0.1 m). The subgrade layer has been constructed at different saturation degrees as follows: 100, 80, 70, and 60%. The tests were carried out using different load amplitudes and frequencies. These experiments investigated the effect of the subgrade degree of saturation on the value of the stresses generated on the surface and the middle (vertical and lateral stresses) and the settlement of the subgrade. In the case of unsaturated subgrade soil, an increase in load frequency has a clear effect on increasing the generated stresses in the subgrade layer, especially with lower saturation levels. However, the results and measurements of these experiments found that the load frequency almost had no effect on the values of the stresses generated on the surface and inside the subgrade layer with a 100% degree of saturation. The results of the investigation demonstrated that, while load frequency had a minimal effect on track-panel settlement, it increased with the load amplitude and subgrade soil saturation degree. The change of settlement of the track panel with the number of cycles has a high rate at the beginning; after a while from that, it decreases gradually until, after some value of the number of cycles, the settlement changes at a very low rate and gradually. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

It is nowadays recognized that the load-transfer P-Y curves methods offer a powerful framework of analysis of the pile response under lateral loading. The aim of this paper is to present a new formulation the P-Y curves to analyze the response of a single pile embedded in clayey soil, on the basis of the CPT test data. The methodology of work consists of analyzing 8 lateral loading tests on fully instrumented piles driven into a homogeneous saturated clayey soil. The P-Y curves were formulated by the PARECT (parabola-rectangle) function, and successful correlation of their parameters, namely the lateral reaction modulus and the lateral soil resistance, with the cone resistance as well as with the lateral pile/soil stiffness ratio was made. After a comparison with the existing PY curves methods, a methodology of analysis by the proposed P-Y curves for piles in normally consolidated to slightly over-consolidated clays was suggested. Moreover, a pile classification according to the pile/soil stiffness ratio was suggested, and the concept of the critical deflection corresponding to the threshold of domain of large deflections of piles was introduced. Validation process was launched by applying this methodology to a centrifuged scale model of a single bored pipe pile in a saturated slightly over consolidated clay. Direct comparison of the load-deflection curves showed an excellent prediction of the small deflections up to about 2% of the pile diameter. Beyond this value, the boundary conditions at the pile tip have an influence on the results, but showed a relatively pessimistic prediction. [ABSTRACT FROM AUTHOR]

Searching for alternative material options to reduce the extraction of natural resources is essential for promoting a more sustainable world. This is especially relevant in construction and infrastructure projects, where significant volumes of materials are used. This paper aims to introduce three alternative materials, crushed ground glass (GG), recycled gypsum (GY) and crushed lime waste (CLW), byproducts of construction industry geomaterials, to enhance the mechanical properties of clay soil in Cartagena de Indias, Colombia. These materials show promise as cementitious and frictional agents, combined with soil and cement. Rigorous testing, including tests on unconfined compressive strength (qu) and initial stiffness (Go) and with a scanning electron microscope (SEM), reveals a correlation between strength, stiffness and the novel porosity/binder index (η/Civ) and provides mixed design equations for the novel geomaterials. Micro-level analyses show the formation of hydrated calcium silicates and complex interactions among the waste materials, cement and clay. These new geomaterials offer an eco-friendly alternative to traditional cementation, contributing to geotechnical solutions in vulnerable tropical regions. [ABSTRACT FROM AUTHOR]

Conducting quantitative research on the microstructure of soft clay can reveal the essence of its soil mechanical behavior, which is of important practical significance for geological disaster risk assessment and prevention. To quantitatively investigate the microscopic properties of natural structured clay, soft clay soils from various sedimentary environments in the Hangzhou Estuarine Bay area were chosen as the research subject in this study. Subsequently, a comprehensive investigation into the microstructure of clay was conducted, involving X-ray phase analysis and SEM imaging analysis. The results revealed the following: (1) In comparison to the deep clay deposited in fluvial-lacustrine environments, the shallow mucky clay in marine sediments had a higher clay mineral content, accounting for 48%. Illite makes up the majority of it, with minor levels of kaolinite and montmorillonite being present. (2) The shallow mucky clay in the Hangzhou Estuarine Bay area had a typical agglomerate-flocculated structure. In contrast, the deeper clay showed a flocculated structure with less uniform particle sizes, strong stacking randomness, poor directional alignment of soil pores, and tends to form arrangements where edges are adjacent to faces or edges are adjacent to other edges. (3) Compared to the deep clay deposited in fluvial-lacustrine environments, the marine-deposited shallow mucky clay displayed orderly pore arrangements, strong directional alignment, significant pore shape variability, and minimal pore size changes between adjacent pores. The microstructure of soil plays a crucial role in determining the physical, mechanical, and other engineering properties of the soil. This study provides insightful information about the relationship between clay microstructure and geotechnical characteristics in Hangzhou and the surrounding areas. [ABSTRACT FROM AUTHOR]

Mitigation of global climate change by means such as soil carbon (C) sequestration has become an important area of research. Soil organic matter (SOM) that is stabilized with clay minerals is the most persistent in soils. Currently, little is known regarding the C sequestration ability of nanoclay extracted from Vertisols in semi-arid regions. Therefore, the aim of this study was to extract and characterize nanoclay and bulk clay from a Vertisol from Iran, in terms of physicochemical surface properties and resistance of SOM to chemical oxidation. The clay fractions were studied before and after H2O2 treatment by total C analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), pyrolysis gas chromatography mass spectrometry (GC–MS), Fourier transform infrared (FTIR) spectroscopy, specific surface area analysis, and zeta potential. TEM and SEM images showed that the diameter of the extracted nanoclays was 16–46 nm and their morphology was more porous than bulk soil clay. The nanoclay had a much greater specific surface area (111.9 m2 g−1) than the bulk clay (67.9 m2 g−1). According to total C, FTIR, and zeta potential results, the nanoclay was enriched with 1.4 times more C than the bulk clay after peroxide treatment, indicating enhanced soil C stabilization in the nanoclay. About 45% of the peroxide-resistant SOM in the nanoclay was associated with N-containing compounds, indicating that these compounds contribute to SOM stability. The results demonstrate important role of nanoclay in soil C sequestration in Vertisols. [ABSTRACT FROM AUTHOR]

Civil engineering faces a substantial challenge when dealing with soft and compressible clayey soils. Conventional soil stabilization techniques involving ordinary Portland cement (OPC) result in notable CO2 emissions. This study explores the utilization of basic oxygen furnace (BOF) slag, a by-product of steel production, for strengthening kaolin clay. This research investigates the influence of BOF slag particle size, BOF slag content, and the use of activators such as lime and ground granulated blast-furnace slag (GGBFS) on the stabilization of kaolin clay. The strength development is assessed through unconfined compressive strength (UCS) test, bender element (BE) test, and scanning electron microscopy (SEM). The findings reveal that higher BOF content and extended curing periods enhance soil strength, and lime and GGBFS effectively augment the stabilizing properties of BOF slag. Stabilizing kaolin clay with a 30% BOF/GGBFS mixture in a 50/50 ratio with 1% lime and curing for 7 days yielded a compressive strength of 753 kPa, meeting the Federal Highway Administration's requirement for lime-treated soil. These combined measures contribute to developing a more robust and stable material with enhanced geotechnical properties. [ABSTRACT FROM AUTHOR]

Population expansion and the development of technology have led to an increase in construction activities. In many cases, foundation grounds do not have a high enough bearing capacity and are not capable of ensuring the safe exploitation of the construction. A soil with poor mechanical characteristics must be improved using various methods, such as adding hydraulic binders (lime and cement), natural fibres, or more recently, plastic waste materials. This work aims to study the behaviour of plastic waste materials made from polyethylene terephthalate (PET) in soil improvement. Thus, the mechanical characteristics of a clay improved with shredded PET were studied. PET was added in relation to the dry mass of the clay, in percentages of 2%, 4% and 6%. The studied clay was collected from a construction site around Cluj-Napoca, Romania, from a depth of 1 ÷ 10 m. PET was provided by a local plastic waste repository. It comes from recycled water, beer and soda bottles and was cleaned using specific methods for cleaning and recycling plastic waste. PET was shredded into irregular shapes with sizes ranging from 3 mm to 12 mm and was randomly distributed in the test specimens. Compression and direct shear tests were carried out to study the compressibility and shear parameters of the improved soil (internal friction angle and cohesion). The experimental results showed an improvement in the mechanical characteristics of the clay even at a low PET addition of 2% and 4%. This method can contribute to solving two current problems of the modern world: reducing pollution by recycling plastic waste materials and using them to improve the mechanical characteristics of soil. [ABSTRACT FROM AUTHOR]

Anchorage failure of a suction anchor is more likely to occur in low-strength muddy clay. This paper focuses on the failure behaviors of suction anchors and muddy clay stress responses. The centrifugal model test was used to study the loading processes of suction anchors with various pulling angles. Firstly, the multi-stage developing process of anchoring force was analyzed according to the test results. Numerical modeling was used to validate the test results. The displacement of the suction anchor and muddy clay soil were analyzed using the numerical results. Then, the numerical and testing results were compared to analyze the horizontal soil pressure responses around the suction anchors. It was found that the change in loading direction affected the distribution and development of soil stress. The horizontal soil resistance played a crucial role in improving the bearing capacity. The soil stress variation and anchor displacement revealed that the suction anchors exhibited multi-attitude coupling movement during the inclined pulling. The vertical pulling suction anchor showed shear–slip failure behaviors, while the inclined pulling suction anchors showed compression–shear–slip coupling failure behaviors. The results of this study provide insight into the interaction mechanism between suction anchors and muddy clay, serving as a reference for the design and application of suction anchors. [ABSTRACT FROM AUTHOR]

In an effort to mitigate the harm caused by the irregular use of agrochemicals, a safer release system using biopolymers is promising due to their availability, biodegradability, and eco-friendliness. Herein, controlled-release materials for NPK fertilizer were formulated using clay-based graft biopolymer composites. The clay soil sample was collected and classified through Skempton's laboratory tests for soils and used as filler in starch-grafted sodium alginate (ST-g-SAG) with different percentages of clay. The clay-based graft biopolymer composites were synthesized via a microwave-assisted method. The biopolymer composites were characterized by FTIR, SEM, and EDS. The materials were loaded with NPK fertilizer, and a leaching test was conducted via a conductometric method to ascertain their release capacities. Biodegradation studies and the effect of humidity on the release of the NPK fertilizer were studied. Results of classification studies of the clay show Ca-montmorillonite (Ca-MMT) type. The average percent graft yield of starch-grafted sodium alginate/Ca-MMT (ST-g-SAG/Ca-MMT) was 83%. The results from FTIR and EDS showed that OH-, COO-, and CONH2 were responsible for the absorption of water. The release profile of the active NPK in the biocomposites ranged from 1% to 103%. Biodegradation results also showed a significant breakdown in biopolymer structure and mass loss. The release of active NPK from the material was humidity-responsive. [ABSTRACT FROM AUTHOR]

The physical and chemical characteristics of the clay are highly dependent on the geospatial conditions. Clays procured from three geospatially distinct locations (Raithal in Jalore District, Rajasthan, India; Gajsinghpura and Jheepasani in Jodhpur District, Rajasthan, India) near the edge of the Thar Desert in India have been used in this study. Frustum-shaped 3L green composites were prepared by a three-step process by mixing clay and sawdust in equal volume fractions, similar to local G-filters in India. Here, green composites were sinter-fused at various temperatures to create ceramic water filters. Raithal and Gajsinghpura clay-based ceramics showcased similar behavior in grain length variation while being sintered at 650°C, 750°C, and 850°C, respectively. Further, the pore dimensions, thermal stability, fracture toughness, and flow characteristics of these ceramic water filters baked at 750°C were studied. The gravity-based cumulative water discharge rate proportionally increased with the pore surface area of distinct ceramics from different locations. Micro-CT (3.4 m resolution) data visually confirms that Gajsinghpura clay has a rigid structure with a large pore volume. Results from thermogravimetric analysis showcase the reorganization of the gibbsite layer in Jheepasani clayey soils. Crystalline and amorphous characteristics were observed from micrographs of Gajsinghpura and Raithal ceramic samples. Raithal clay ceramic frustum bases were the toughest. Gajsinghpura and Raithal clay-based ceramic filters show similar behavior in Escherichia coli removal as a function of average pore diameter. [ABSTRACT FROM AUTHOR]

Clayey soils in Raithal, Jalore, Rajasthan, India, have been used for local manufacturing of clay ceramic water filters by potter communities. Potters are trying clayey soils from different locations across India to produce these filters. The suitability of clayey soils from Jheepasani, Jodhpur, and Gajsinghpura, Jodhpur, Rajasthan, India, to manufacture these water filters is compared with soils from Raithal, Jalore, Rajasthan, India. The shrinkage limit and maximum dry density were the lowest for Jheepasani soils. Jheepasani soils have quartz in large quantities, while Gajsinghpura soils are characterized by zeolite. Scanning electron microscopy revealed dense, flaky structure of Gajsinghpura soils and a loosely packed matrix in Jheepasani soils. The micrograph of soils depicts the presence of crystalline character in constituents of Raithal and Gajsinghpura soils. A 3L frustum-shaped composite is made by mixing an equal amount of each of the three soils listed above (taken on their own) with an equal amount of burnout material. The mixture is then pressed into the shape. These press-formed frustums were traditionally baked at 750°C in a potter's open-hearth kiln at Banad village, Jodhpur, Rajasthan, India, to get the new 3L ceramic water filters. A maximum percolation rate of 1.8 L/h was observed from filters manufactured using Jheepasani soils. The samples extracted from the walls of Gajsinghpura soil-based ceramic water filters were comparatively more substantial than those manufactured from the soils of Raithal and Jheepasani. The effectiveness of these 3L filters was tested using Escherichia coli as a surrogate for other waterborne pathogens. E. coli removal with a log reduction value of 2.62 was showcased by Raithal soil-based ceramic water filters. On the basis of this result, Raithal soil-based ceramic water filters were found to be functionally better among the three ceramic water filter variants manufactured from clayey soils found near the Thar Desert in India. [ABSTRACT FROM AUTHOR]

Phyllite soil and red clay belong to the soils that negatively impact the engineering performance of railway subgrade and may cause subgrade bulges, uneven subgrade settlement, and other subgrade distresses. In order to make full use of these two soils, a collaborative improvement plan was proposed. A series of tests were conducted to analyze the synergistic effects of lime and red clay on the improvement of phyllite soil. The tests included the no loading swelling ratio, swelling pressure, consolidation, and direct shear tests. Additionally, scanning electron microscopy was used to investigate the role of lime and red clay in soil improvement. The test results show that a red clay ratio of 60% + lime content of 3% is the optimal composite improvement scheme. The scheme led to a 93% reduction in the no loading swelling ratio and an 88% reduction in swelling pressure. Additionally, cohesion, the internal friction angle, and the compression modulus increased by 345%, 73%, and 373%. Red clay and lime had weak synergistic improvement effects on the no loading swelling ratio, the swelling pressure, and the internal friction angle of phyllite soil, that is, the synergistic improvement effect of red clay and lime was less than the sum of the single improvement effect but greater than the single improvement effect. Red clay and lime had a strong synergistic improvement effect on the cohesion and the compression modulus of phyllite, that is, the synergistic improvement effect of red clay and lime was greater than the sum of the single improvement effect. The microstructure analysis test results show that red clay can fill the pores of phyllite soil and improve its immediate strength. Through hardening and cementation, lime can enhance the strength of phyllite soil as well as address the issue of the reduced engineering properties of phyllite soil and red clay when exposed to water. Red clay and lime promote each other's reactions and have a synergistic improvement effect on phyllite soil. [ABSTRACT FROM AUTHOR]

This case study focuses on twelve compacted clay soil samples to understand their fundamental physical and thermal properties. For each sample, the density, thermal conductivity, thermal diffusivity, specific heat, and drying shrinkage were assessed. The identification and characterisation of the materials were also carried out by positioning them into the ternary diagram based on the percentage of sand, silt, and clay. These properties are definitive for the performance characteristics of materials used in rammed earth wall construction. The aim is to provide information for better knowledge and prediction regarding the dynamic heat flow in rammed earth walls. Experimental results show a relatively wide range of values for each property, reflecting the diverse properties of the sampled clays. The thermophysical characteristics of the 12 types of earth analysed showed correlations with reports in the literature in terms of density (1490–2150 kg/m3), porosity (23.22–39.99%), specific heat capacity (701–999 J/kgK), and thermal conductivity (0.523–1.209 W/mK), which indicates them as materials suitable for use in the construction of rammed earth walls. Using test data, a dynamic assessment of heat flow through simulated rammed earth walls was performed. For a better understanding of the results obtained, they were compared with results obtained for simulations where the building element would be made of concrete, i.e., a mineral wool core composite. Thus, heat flux at the wall surface and mass flux, respectively, during the 16 years of operation showed similar evolution for all 12 types of clay material analysed, with small variations explained by differences in thermophysical characteristics specific to each type of S1–S12 earth. In the case of walls made from clay material, there is a stabilisation in the evolution of the water content phenomenon by the 5th year of simulation. This contrasts with walls made of concrete, where the characteristic water content appears to evolve continuously over the 16-year period. Therefore, it can be said that in the case of the construction elements of existing buildings, which have already gone through a sufficient period for the maturation of the materials in their construction elements, the rammed earth wall quickly develops a moisture buffer function. In the case of simulating a mineral wool core composite wall, it cannot perform as a temperature or humidity buffer, exhibiting an enthalpy exchange with indoor air that is only 4% of that of the rammed earth walls; consequently, it does not play a significant role in regulating indoor comfort conditions. Overall, there is confirmation of the temperature and moisture buffering capabilities of rammed earth walls during both warm and cold periods of the year, which is consistent with other reports in the literature. The findings of this research provide a better insight into clay as a material for rammed earth walls for more efficient design and construction, offering potential improvements regarding indoor comfort, energy efficiency, and sustainability. The data also provides useful information in the fields of architecture and civil engineering regarding the use of clay as an eco-friendly building material. The results emphasise the importance of thoroughly understanding the thermophysical properties of clay to ensure the efficiency of rammed earth construction. [ABSTRACT FROM AUTHOR]

The stabilisation of soft soils using the traditional binders cement and quicklime are known to emit large amounts of carbon dioxide. To reduce this carbon footprint, substitutes such as industrial by-products have been thoroughly tested as viable alternatives for soil stabilisation. However, recent research has also shown that biochar from biomass pyrolysis can in some instances have a positive stabilisation effect and even result in a carbon-negative footprint. This paper presents a laboratory study to investigate the stabilisation effect of five industrial by-products and four types of biochar on three natural Norwegian soils: two clays with low and high water contents and one peat with a very high water content. The soils and binders were characterised by their mineralogical and chemical compositions. The biochars had varying stabilisation effects on the clays when combined with cement, with some negative stabilisation effects, whilst the effect was very beneficial in the peat, with a strength increase of up to 80%. The industrial by-products showed opposite results, with beneficial effects in the clays and a strength increase of up to 150%, but negative stabilisation effects in the peat. Correlating the mineralogical and chemical compositions to stabilisation effects was found to be challenging. [ABSTRACT FROM AUTHOR]

In this study, the combined effect of temperature (T) and pore water salinity on electrical surface conduction parameters was investigated. Two new electrical surface conduction parameters, namely, electrical conductivity of effective solid (σs) and size of diffuse double layer (DDL) water per unit volume of soil (χ), were considered in this study. The tested samples included two commercially available clays and four natural clay soils with diverse physico-chemical properties. The two surface conduction parameters were also used to assess the influence of temperature (T) and pore water salinity, as well as the electrical conductivity of free water (σFW), on the evolution of the free swelling index (FSI) of clays/clay soils through experimental methods. The findings suggested that elevated temperature and σFW increased σs but reduced χ, as well as the FSI of clays/clay soils. Furthermore, the rate of reduction for both χ and FSI augmented under the influence of increased free water salinity, particularly for clays/clay soils with high swelling capacity. The combined reductions of χ and FSI provided substantial evidence that clay DDL thickness decreases as T and σFW increase concurrently. [ABSTRACT FROM AUTHOR]

Soil-cutting forces are key indicators of root-tuber harvesters and other soil-engaging tools' performance. To improve operational efficiency, minimise soil disturbance, and reduce fuel consumption, the draught and vertical forces involved in root and tuber crop harvesting must be minimised. Two field experiments assessed the harvester's performance at a depth of 200 mm, varying frequencies, and travel speeds on clay and sandy loam soils. Discrete element models (DEM) were developed and subsequently used to replicate the field experiments and evaluate S-shaped and fork-shaped shovels. Linear regression and ANOVA (p < 0.05) were used to analyse the data. Draught force concurrently increased with speed in both soil textures but decreased with vibration frequency. The draught force decreased by approximately 41% in clay soil and 21% in sandy loam soil when the harvester was operated between 5 Hz and 14.5 Hz and between 10 Hz and 12.5 Hz, respectively. DEM simulations had relative errors of 4% (clay) and 4.7% (sandy loam) for draught force and drawbar power compared to experimental data. The S-shaped shovel was more efficient at crushing and translocating soil–crop mass to the rear of the harvester than the fork-shaped shovel. These DEM soil–crop models are reliable for evaluating other root-tuber harvesting tools. [ABSTRACT FROM AUTHOR]

This research focused on the implementation of different species to evaluate their efficiency in soils disturbed by clay mining. A part of the land was taken and a physical-chemical and microbiological characterization was made to know the conditions of the soil under study before applying the species, then it was divided into four plots of equal measures, of 1.5x1 m, one control and three in which we applied the respective species, this with the objective of evaluating the efficiency of the interaction of the species in the soil contaminated by mining. This study revealed the great capacity of grasses (Maize, star grass and brachiaria grass), and Fabaceae (Yaguaro and Acacia Riparia Kunth), to provide organic materials and nutrients that allowed the evaluation of the efficiency or reactivation of the contaminated soils. It should be noted that the one with the highest efficiency was plot three. [ABSTRACT FROM AUTHOR]

Expansive clay is one of the most widely distributed soils in the world. Due to its rich content of strongly hydrophilic minerals—such as montmorillonite—expansive clay exhibits substantial swelling and shrinkage properties, and overconsolidation. The formation process of undisturbed expansive clay has a long and complicated geological history and innumerable drying–wetting cycles, resulting in the formation of special internal structures. In this study, the mud-to-natural-consolidation deposition process was simulated using a saturated mud-remolded sample preparation device, and then, mud-remolded soil under a certain consolidation pressure was prepared. Subsequently, the effects of the stress history and drying–wetting cycle on its mechanical properties and microstructure were examined through uniaxial consolidation compression experiments, K0 consolidation experiments, and pressure plate experiments of undisturbed soil, mud-remolded soil, and a drying–wetting cycle sample. The results showed that the mud-remolded soil completely broke the natural structure of the undisturbed soil, with the structural characteristics of the remolded soil being restored to a certain extent after the drying–wetting cycle. This not only reduced the void ratio of the soil sample, but also changed its compressibility and water retention characteristics, revealing the role of atmospheric drying–wetting cycles in the natural overconsolidation state of expansive clay and providing a theoretical basis for understanding their overconsolidation characteristics. [ABSTRACT FROM AUTHOR]

In the literature, the influence of spatial variability of the undrained shear strength of foundation soils on the bearing capacity of footings is limited to footings seated directly on the foundation. This is an unlikely arrangement in practice. This paper revisits the footing problem by considering a thin granular layer between a strip footing and soft foundation soil using analytical and stochastic numerical modeling. The analyses are extended to the case of a geosynthetic-reinforced granular layer and to the idealized case of no granular layer. The study shows that the probability that the ultimate bearing capacity for the footing is smaller than the deterministic design value is greater for all three scenarios with randomly uniform clay soil than for the same soil with isotropic or anisotropic spatial variability of strength at practical levels of reliability index β (e.g., β≥3.09 for a permanent footing). The reason for this outcome, which may appear counterintuitive, is explained. Design charts are provided to estimate the deterministic design bearing capacity of a rigid strip footing required to meet a range of target reliability index for the three footing scenarios examined in this study. [ABSTRACT FROM AUTHOR]

The earliest method of waste disposal is dumping waste in landfills. The important component of landfills which prevents the passage of leachate to the subsoil is defined as the bottom liner. A landfill liner must contain a specific range in terms of swelling behavior, strength, and permeability before placing down beneath the constructed landfills. The present paper summarizes the detail of the different materials and their feasibility which satisfy the criteria to be used as landfills liner. The detail of findings of microstructural analysis (SEM–EDX, XRD, FT-IR, etc.) along with the waste materials which compact the particles and enhance the strength and stability of soils is also discussed. A lot of landfill liner materials such as Bentonite, sand, fly ash, cement, biochar, marine clay, lateritic soil, and geosynthetics have been used to enhance the geotechnical properties of liners. Among all, geosynthetic clay liner (GCL) and compacted clay liner (CCL) show increased hydraulic conductivity for clay soil with high plasticity whereas this value reduces for clayey soil having low plasticity with the increase in the concentration of the salt solution. The hydraulic conductivity of the mix containing biochar, bentonite, and sand is found to be 1 × 10−9 m/s. The hydraulic conductivity and shear strength of the soil increases while the compressibility of the soil decreases with an increase in the biochar percentage having smaller particle size. Also, the alkaline activator is suggested to be best for soil stabilization as compared to standard Portland cement. The development of new materials must be environmentally sustainable and should contain sufficient shear strength so that it can sustain the overburdened load of dumped waste. It should also be free from cracking so that the contamination of subsoil and groundwater can be minimized. [ABSTRACT FROM AUTHOR]

In the present study, laboratory model tests and numerical analysis are carried out to study the immediate, and consolidation settlement of shallow foundations rested on clayey soil. The purpose is to evaluate the immediate and consolidation settlement of different cases and compares them with the calculated values using theoretical equations; the numerical analysis is utilized by the Plaxis-3D program for developing the finite element model, whereas the soft soil model was used for simulation. It was studied the effect of three parameters on the behavior of the foundation for immediate and consolidation settlement, these parameters are soil cohesion, the pressure applied on the foundation, and layer thickness. The obtained results indicated that the simulation using the soft soil model underestimates the immediate settlement by about 30 % and gives excellent results for predicting consolidation settlement. The total settlement of shallow raft foundation rested on a clay layer of depth three times raft width to one time was increased by about 66 %. The consolidation settlement is much higher than the immediate in clayey soils, however, the average of immediate to consolidation settlement is equal to 0.3 % for pressure 20 kPa, and increases with rising applied pressure until it reaches 1.2 %. The numerical analysis revealed a lower value than the calculated using the theoretical equation for immediate settlement, while for consolidation settlement, the results are close except for the soft clay condition cu = 20 kPa. [ABSTRACT FROM AUTHOR]

Road and subway tunnels in soft clay soils subjected to traffic loading often cause lager settlement. It can pose danger to the surrounding buildings and structures. Hence, it is necessary for engineers to correctly predict the long-term deformation of saturated clay foundations under cyclic loading. In this paper, a series of dynamic triaxial tests were carried out on Nanning clay to investigate the effect of loading frequency and cyclic stress on axial strain accumulation of clay under undrained condition. Results show that loading frequency has a great effect on the axial strain accumulation of clay. Based on the experimental results, an empirical formula for calculating the accumulated deformation of saturated clay under cyclic loading was presented. [ABSTRACT FROM AUTHOR]

This study aimed to theoretically evaluate soil thrust on a clay slope as a reaction force associated with the motion of an off-road tracked vehicle. The existing concept of the potential failure modes of a clay block on flat ground has extended to determine the soil thrust of sloped clay ground. Based on the upper-bound limit analysis, the soil thrust under the most critical failure was derived for three potential failure modes: block, triangular-wedge, and trapezoidal-wedge failures. Specifically, the influence of the slope angle, the shear strength of clay, the weight of a vehicle, and the geometry of a track system on the soil thrust was investigated. Only the block and triangular wedge failure modes were able to occur, and the geometry of a single-track system could lead to different failure modes. Under the block failure mode, the soil thrust decreased as the slope became stiff, and the vehicle weight increased. On the other hand, the soil thrust decreased as the slope angle decreased under the triangular-wedge failure mode. [ABSTRACT FROM AUTHOR]

Soils contaminated by mining activities are a major environmental concern, and to avoid this type of environmental impact, carrying out high-cost processes is necessary. For this reason, a solution is proposed in this study in order to eliminate the soils contaminated by mining activities and, in turn, prevent the soil's contaminating elements from causing harm. All this is achieved by using contaminated soils as raw materials for the production of ceramics for bricks. For this purpose, the materials were initially characterized physically and chemically, and different ceramic test pieces were manufactured with different percentages of clay and contaminated soil, subsequently determining the physical properties and the leaching of toxic elements. In this way, it was possible to evaluate, via innovative data mining and fuzzy logic techniques, the influence of the contaminated soil's contribution on the properties of ceramics. Based on this, it was possible to affirm that the contaminated soil incorporation negatively affects the physical properties of ceramics as well as the leaching of polluting elements. The ceramic formed by contaminated soil and clay has a lower compressive strength, and it is associated with lower linear shrinkage and lower density, as well as higher porosity and cold-water absorption. However, the addition of different percentages of contaminated soil (up to 70%) to clay created a ceramic that complied with regulation restrictions. Therefore, it was possible to obtain a sustainable material that eliminates environmental problems at a lower cost and that fits within the new circular mining concept thanks to fuzzy logic techniques. [ABSTRACT FROM AUTHOR]

Land subsidence in coastal and delta cities often results in infrastructure and residential building damages, while also increasing the area's flooding vulnerability. The coastal cities of Messolonghi and Aitolikon are typical examples, as they are built on top of old stream deposits near the coast. In the last several years, the gradual subsidence of the sites, combined with the impact of climate change, resulted in multiple floods. The rush of seawater over the lowlands has also been reported. Persistent scatterer interferometry (PSI) is a remote-sensing technique that can provide a reliable and cost-effective solution, as it can be used to identify and monitor soil displacements. In this study, a novel parallelized PSI (P-PSI) processing chain, developed by the Operational Unit Center for Earth Observation Research and Satellite Remote Sensing (BEYOND) of the National Observatory of Athens, as well as the Copernicus EGMS product were used to identify these displacements. The results were examined in correlation with other potential factors such as the overexploitation of the underground water, the natural compaction of the clay soil layers, the primary and secondary consolidation due to the external construction loading, the oxidation of the organic soils, tidal gauge data, precipitation data, and ground truth data. In Messolonghi, various deformation rates were recorded, with maximum mean values of −5 mm/year in the eastern part, whereas in Aitolikon, the maximum values were around −4.5 mm/year. The displacements were mostly attributed to the primary consolidation due to the building loads. Deformation patterns and their correlation with precipitation could also be witnessed. It was evident that the increased precipitation rates and sea level rise played a leading role in the constant flooding. [ABSTRACT FROM AUTHOR]

The main objective of this paper is investigation of clayey soil setup effects on axial "resistance" and "stiffness" of small-scale piles with special attention on "overconsolidation ratio" (OCR) and "installation method". A consolidation chamber is developed and an instrumented model pile is either driven or jacked-in through saturated consolidated Kaolinite clay at different OCRs of 1.2 (normally consolidated, NC) and 4.8 (over consolidated, OC). The pile was static load tested at different time intervals of 1 h through 90 days. Higher pore pressures are induced during pile installation in NC compared to OC clay. The frictional resistance of OC soil is higher than NC at end of drive as well as end of setup in both driven and jacked-in piles. The frictional resistance of jacked-in piles is greater than driven piles at end of drive, but due to higher rate of setup, the long-term frictional resistance of driven piles is shown to be greater, attributed to more disturbance of the soil during installation of driven piles. Attempts are made to differentiate between the contributions of dissipation of excess pore pressure and non-pore pressure components for each consolidation condition and pile installation method. A relation is proposed to quantify the pile stiffness variations over time due to soil setup. [ABSTRACT FROM AUTHOR]

The degree of the over-consolidation ratio (OCR) of silty clay affects the soil's mechanical properties and in situ test results. The present study utilized numerical analysis to investigate the behavior of cone penetration and pore pressure dissipation in typical silty clay soils, while also taking into account the impact of the over-consolidation ratio (OCR). Effective stress finite-element analyses, which accounted for considerable deformation, were carried out at various OCRs. The model assumed the soil as a homogeneous material obeying the modified Cam Clay (MCC) model. The significant advance of this work is the evaluation of the effect of OCR on penetration resistance and pore pressure test data and the calculation formula of OCR and ch in typical silty clay. An inversion method based on the results of piezocone penetration tests was proposed in terms of strength and the over-consolidation ratio of the silty clay, which is of great importance for the inversion of soil parameters in the Yellow River Delta region. This paper presents a consolidation coefficient inversion method of typical normally and over-consolidated silty clays and corrected the disadvantage that traditional conversion methods could not take OCR effects into account. [ABSTRACT FROM AUTHOR]

The utilization of industrial by-products as stabilizers is gaining attention from the sustainability perspective. Along these lines, granite sand (GS) and calcium lignosulfonate (CLS) are used as alternatives to traditional stabilizers for cohesive soil (clay). The unsoaked California Bearing Ratio (CBR) was taken as a performance indicator (as a subgrade material for low-volume roads). A series of tests were performed by varying the dosages of GS (30%, 40%, and 50%) and CLS (0.5%, 1%, 1.5%, and 2%) for different curing periods (0, 7, and 28 days). This study revealed that the optimal dosages of granite sand (GS) are 35%, 34%, 33%, and 32% for dosages of calcium lignosulfonate (CLS) of 0.5%, 1.0%, 1.5%, and 2.0%, respectively. These values are needed to maintain a reliability index greater than or equal to 3.0 when the coefficient of variation (COV) of the minimum specified value of the CBR is 20% for a 28-day curing period. The proposed RBDO (reliability-based design optimization) presents an optimal design methodology for designing low-volume roads when GS and CLS are blended for clay soils. The optimal mix, i.e., 70% clay blended with 30% GS and 0.5% CLS (exhibiting the highest CBR value) is considered an appropriate dosage for the pavement subgrade material. Carbon footprint analysis (CFA) was performed on a typical pavement section according to Indian Road Congress recommendations. It is observed that the use of GS and CLS as stabilizers of clay reduces the carbon energy by 97.52% and 98.53% over the traditional stabilizers lime and cement at 6% and 4% dosages, respectively. [ABSTRACT FROM AUTHOR]

In this paper, a modified/extended rotational hardening (RH) rule is applied to the nonassociated simple anisotropic constitutive model, SANICLAY-D, for clayey soils. In the proposed model, the destructuration mechanism, as well as zero and nonzero fabric anisotropy at critical state (CS), are considered. A detailed model formulation with the RH rule that yields a unique CS in the e-ln(p′) space is presented including an appropriate form of the relatively simple substepping integration algorithm. In addition, the model is implemented into ABAQUS finite-element software using a User-defined Material (UMAT) subroutine and used in the simulation of various experimental tests. The modified SANICLAY-D model (SANICLAY-MD) is meticulously calibrated step by step for Saint-Alban sensitive soft clay. Drained and undrained triaxial tests after various consolidation paths as well as the direct simple shear (DSS) test are simulated for Saint-Alban and Bothkennar clays as a boundary value problem. Simulation results approve the SANICLAY-MD model's performance in the prediction of the natural soil behavior. Results show that neglecting the effect of fabric anisotropy at CS and destructuration of natural clays can lead to inaccurate prediction in the constitutive modeling of intact soft soils. [ABSTRACT FROM AUTHOR]

In this article, the effects of environmental acidity on the mechanical and volumetric properties of cement-stabilized clay soils have been investigated through various tests on experimental scale. In this study, a problematic clay was chemically stabilized by cement under three treatment conditions including short term, medium term, and long term with different conditions varying from acid to alkaline environments, which were tested by different methods to evaluate their mechanical and volumetric behavior and properties. Mechanical characteristics assessment tests in this study include compaction tests, and unconfined compressive strength, which was conducted on samples under different conditions in terms of acidity and treatment time. The results of the study indicated that soil improvement by cement increases the mechanical strength and decreases the rate of soil swelling over time and treatment duration. However, the degree of acidity of the environment affects the chemical reactions of soil and cement, especially cement hydration, which causes changes in soil strength and volume variation due to swelling. [ABSTRACT FROM AUTHOR]

In this paper, the finite element method (FEM) is applied to calculate the bearing capacity of two footings having the aspect ratio L/B (where L and B are the length and width of the footing, respectively) equal to 1, 2 resting on one-layer and two-layer soil. Soil profile contains two soil types including sand and clay. The soil strip is 500mm × 500mm × 350mm; however, only a quarter of the model (250mm × 250mm × 350mm) is examined in the study. Two primary situations are investigated in this study. In the first situation, the one-layer system is supposed to be sandy soil with footing overlays on medium-dense sand. The soft clay/stabilized clayey layer is supposed to be on top of the sandy soil in the second condition, with the footing resting on top of the soft clay/stabilized clay. The influence of layer thickness, aspect ratio, and material property on the bearing capacity value and footing failure mechanism is studied for eight different combinations of layered soil. The bearing capacity for a one-layer case is also estimated, and it agrees well with Vesic (1973), Hansen (1970), and Terzaghi's (1943) equations. The bearing capacity of footings is observed to decline when the height of unstabilized clayey soil increases, and it increases when clayey soil is stabilized with molasses, waste foundry sand, and lime alone and in combination with each other. [ABSTRACT FROM AUTHOR]

Damage caused by soils subject to change in volume beneath light structures, particularly low-cost housing units of masonry construction, is unacceptably frequent. It has led to the demolition of many such units within a small fraction of their design lifespan. Perhaps the most spectacular such failure is Lerato Park in Kimberley, where the development was demolished within four years. The reason for this failure is examined in Stott and Theron (2016). The normal ways of attempting to reduce heave damage have involved increasing the strength and stiffness of foundations, together with reducing masonry panel size through movement joints and increasing the strength of the panels. While these measures have improved the situation somewhat, they are expensive and have proved to be only partially successful. This investigation examines the possibility of increasing the ability of masonry panels themselves to accommodate significant distortion without sustaining unacceptably serious cracking. The existing specifications in SANS 10164 (SANS 10164 2000) are shown to allow considerably greater inherent flexibility than current practice allows. This is dependent on the specified quality of sand (frequently ignored) and water demand requirements, as specified in South African standards, being adhered to. [ABSTRACT FROM AUTHOR]

Copyright of SDU Journal of Engineering Sciences & Design / Mühendislik Bilimleri ve Tasarım Dergisi is the property of Journal of Engineering Sciences & Design and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nanomaterials have been widely used for improving the physicochemical properties of geomaterials. However, quantitative interpretation of the microscopic mechanisms is still not well understood. In this study, a statistical principle was applied to study the microscopic characteristics of nano-silica (NS) modified silty clay. We use mercury intrusion porosimetry (MIP) to measure the micro-pore parameters (median pore diameter and cumulative volume of pore diameters smaller than 0.1 µm) based on various NS-modified silty clays (NS mass contents 0, 0.25%, 1%, and 3%). The test results indicate two micro-pore parameters have significant randomness and uncertainty, and soil pores become smaller and more compacted. Furthermore, four potential probability distributions were selected to compare with measured data. All distributions agree excellently with the experimental data, and three distributions satisfy the hypothesis testing, except the Weibull distribution. Finally, according to the information spread estimation method and chi-square test effect evaluation indexes, the normal distribution was proposed because it has the optimal described effect for the statistical characteristics of NS-modified silty clay. These results have important implications for understanding the randomness and evolution of microstructures of NS geomaterials, which are helpful to guide the evaluation of freezing process and water transport in modified soils. [ABSTRACT FROM AUTHOR]

The accumulation of soil organic matter (SOM) is vital to the agronomic and environmental functioning of agroecosystems, yet the relative influence of inherent soil properties and agricultural management practices on SOM dynamics are not often addressed in individual studies. Using a network of 218 operating farm fields across Wisconsin and southern Minnesota, USA, this research employs single variable analysis (ANOVA and regression) and regression tree analysis to assess the effects of soil properties (texture, drainage class, and pH) and management variables related to crop rotation, tillage, cover cropping, and manure application on SOM, as well as total organic carbon (TOC) and total nitrogen (TN) in the upper 15 cm. Single variable analysis revealed that greater SOM, TOC, and TN were associated with poorly drained soil, tile‐drained fields, high clay content soil, and high biomass crop rotations. SOM and TOC were strongly related (R2 = 0.71), but different regression trees were produced; SOM was most influenced by clay content, while TOC was most influenced by drainage class. Future assessment for the building of SOM or TOC should be conducted with drainage and texture class categories and on a regional basis, given that these factors influence the practices that occur within landscapes. A rapid building of datasets through unstructured sampling, including an abundance of metadata, should be a research priority in agricultural science to identify practices to build SOM on a regional basis. [ABSTRACT FROM AUTHOR]

The soil resistances along the embedded ground chain affect the pull-out capacity of anchor as they determine the magnitude and direction of tension at the padeye. To facilitate analyses, the chain was usually simplified as a cylindrical line. The chain segment with actual geometry, buried deeply in clayey soil, is studied using a large deformation finite element approach to overcome severe distortion of soil elements around the chain. The uniaxial resistances obtained by the large deformation analyses are verified by comparison with the existing model tests and simplified solutions, followed by presentation of the yield envelope against combined loading. Both the probe test and swipe test are used to form the yield envelopes, and their results have good consistency. The influence of roughness of chain–soil interface on the soil resistances is quantified as well. It is found that the envelope of the chain segment with actual geometry is smaller than that against the simplified cylindrical shape; therefore, the most convenient design may not be the safest option. [ABSTRACT FROM AUTHOR]

Application of vertically installed columnar materials made of natural gravels or crushed aggregate is one of the commonly implemented practices to improve the performance of soft clay grounds under footing load. Alternative materials like cinder gravel also plays a reinforcing role when blended with soft clay. However, information on the precise extent to which a vertically installed cinder gravel column is effective in improving the properties of a clay foundation and its potential response to the permanently applied footing load has not been well documented in the literature. Hence, the current study specifically aimed at evaluating the effectiveness of geotextile-encased cinder gravel column in improving deformation and bearing capacity of soft clay ground. The experimental model which considered installation of a single geotextile-encased cinder gravel column into soft clay was considered. A cylindrical steel container was used in designing the experimental test. The container was filled with clay soil and the cinder gravel column was vertically installed through a replacement method. Finding of the study revealed that ultimate load-bearing capacity of the soft clay foundation after being reinforced with conventional cinder gravel was 1.85 times that of the untreated soft clay soil. The load-carrying capacity of the clay soil decreased with increment in diameter of the column whereas it is directly related to the volume replacement ratio. With regard to directional improvement, the vertical reinforcement performs better than the horizontal geotextile strips in cinder gravel column from bearing capacity improvement view point. In lessening settlement, however, application of horizontal geotextile discs at spacing ranging between half- and full-column diameter overweighs performance of the vertical encasement. In summary, application of geotextile encasement to the top 75% of the clay thickness is sufficient to come up with optimum improvement in bearing capacity and encasing the entire thickness is not necessarily required. [ABSTRACT FROM AUTHOR]