Engineering Characteristics Of Soil Research Articles

AN EXPERIMENTAL STUDY ON STABILIZING COHESIVE SOIL USING MICROBIALLY INDUCED CALCIUM CARBONATE PRECIPITATION

Bio-cementation is an environmentally friendly procedure grounded on microbial induced carbonate precipitation mechanism, occurring in environments abundant in calcium. In the effort to bolster soil stability, traditional urea is combined with bacteria to enhance the mechanical properties of soil. The research delves into the microbial mechanisms involved in microbially induced calcite precipitation, highlighting the role of urease-producing bacteria in facilitating calcium carbonate precipitation within the soil structure. This also entails pivotal laboratory and field experiments, evaluating the efficacy of microbially induced calcium carbonate in improving soil engineering characteristics, such as strength, permeability, and durability. Furthermore, this process can be employed across various soil types, offering adaptability in geotechnical applications. Additionally, we investigate the environmental consequences and sustainability aspects by underscoring its potential as an eco-friendly substitute for soil enhancement. Nonetheless, challenges such as optimizing bacterial activity, regulating the precipitation process, and ensuring even distribution of calcium carbonate within the soil necessitate further exploration. Based on the envisioned review, it contributes to the comprehension of MICP as a promising method for soil stabilization, providing insights for researchers, practitioners, and policymakers keen on sustainable and inventive approaches to geotechnical engineering. Key Words: Bio-geotechnical engineering, soil stabilization, Microbially induced calcium carbonate Precipitation, Soil improvement.

Enhancing the engineering properties of gypseous soils by adding the Anthan polymers

Large areas of soil in Iraq are formed up of gypsum soil. As a result, understanding the habits of this soil and its treatment approach is critical, because its current solution is to replace gypsum soil before beginning any building activity. This study used gypsum soil from Tikrit City, which has a gypsum concentration that is around 38%, and the goal of the study is to illustrate the impact of the polymer on the gypsum soil parameters. Simultaneously, researchers are investigating the beneficial effects of polymers on the behavior of gypsum soil. The percentages of the polymer additive (5%, 7.5%, 10%, 12.5%, and 15%) were weight percentages, while the soil tests were chemical, physical, and engineering. When the percentage of additive was increased from 0% to 15%, Soil engineering characteristics enhanced the collapse of the from 5.11 to 1.21, cohesion improved from (28.98 KN/m2) to (51.16 KN/m2), and angles of internal friction decreased from 33.190 to 38.850.

Cost Comparison of Flexible Pavement on Weak Sub-Grade Soil Modified with Lime and SD

The effectiveness of flexible pavement is affected by the subgrade quality. The subgrade refers to a compacted layer of soil that provides sideways support to the pavement. When constructed on a weak subgrade, it negatively impacts the pavement's performance, leading to a shorter lifespan. Traditionally, the common method to stabilize a soft subgrade involves removing the weak soil and replacing it with stronger soil. However, due to the high expenses associated with soil replacement, highway agencies are exploring alternative approaches to constructing highways on soft subgrades. Soil stabilization is a commonly employed alternative in pavement construction, serving as an effective method to enhance the engineering characteristics of soil, including its strength and stability. This paper focuses on the utilization of lime and stone dust (SD) as admixtures for an efficient ground improvement technique over weak subgrade soil deposits. The California Bearing Ratio (CBR) test is conducted by making the specimens of weak subgrade by adding the variable percentages of a mixture of lime and SD. First, the soil was mixed up with lime to 12% by weight with an increment of 3% again the soil was mixed with SD with increments of 10% up to 50% by weight of soil. The study determined an optimal lime content of 3% based on the geotechnical properties of the mixture and the cost considerations of lime and the weak subgrade. Following this, SD was added to the optimized lime-weak subgrade mixture in varying increments of 10% by weight, up to a maximum of 40%. The modified mixes were then evaluated for their CBR and maximum dry density values. The CBR is increased to 15% and the total pavement thickness decreased to 725 mm for 50% SD addition with 4.89 % in cost reduction.

Investigation on the microstructural characteristics of lime-stabilized soil after freeze–thaw cycles

Saline soil in Northwest China is susceptible to frequent and severe freeze–thaw cycles (FTC), resulting in railway and pavement disasters, emphasizing the need for stabilizing inadequately constructed soils. The engineering characteristics of soils can be changed after FTCs, which results from the variation of microstructure. Physisorption experiments (BET), mercury intrusion porosimetry (MIP), and scanning electron microscopy (SEM) were employed in this research to investigate how FTCs affected the micro-characteristics of lime-stabilized saline soil. According to the results, at the beginning of FTCs, the specific surface area (SSA) increased and then reduced after 3 FTCs. Moreover, the pores presented a bimodal characteristic and could be divided into inter- and intra-aggregate pores. The pore size distribution of the stabilized saline soil was altered by the FTCs. Additionally, the FTCs reduced the porosity of pores between 2 ∼ 22 μm and increased their complexity, while also creating more directional pore orientation. The results of this paper are believed to help advance soil stabilization methods and offer useful insights into the microstructural characteristics of lime-stabilized saline soil.

Soil Stability: An Experimental Investigation Utilizing Bagasse Ash in Combination with Guar Gum and Xanthan Gum Biopolymers

This study presents an experimental investigation aimed at enhancing soil stability through the synergistic application of bagasse ash in conjunction with Guar gum (GG) and Xanthan gum (XG) biopolymers. Soil stabilization is a critical aspect of construction and land management, especially in regions where red soil predominates. Due to its pozzolanic qualities, the by-product of sugarcane processing known as bagasse ash has demonstrated potential as a soil stabilizer. Guar gum (GG) and Xanthan gum (XG), natural biopolymers, have demonstrated promise in improving soil engineering characteristics. This research contributes to the evolving field of sustainable soil stabilization techniques, offering insights into the potential of bagasse ash and biopolymers in mitigating soil-related challenges. In the current study, Xanthum gum (XG) and Guar gum (GG) in varied percentages was employed in experimental experiments on red soil as a material for soil improvement. In this investigation, soil was also replaced with Bagasse ash up to 10% of its volume and its strength attributes were assessed. It was found through studies utilizing different Biopolymers concentrations (XG & GG) the soil's strength was improved.

A Review on Soils Treated with Biopolymers Based on Unsaturated Soil Theory.

Adding different materials to soil can improve its engineering properties, but traditional materials such as cement, lime, fly ash, etc., have caused pollution to the environment. Recently, biopolymers have shown many advantages, such as economy and environmental protection, which make them applicable to geotechnical engineering. This study summarizes the effects of biopolymers on soil's engineering properties and the main directions of current research. Firstly, the advantages and disadvantages of a variety of widely used biopolymer materials and their effects on the specific engineering characteristics of soil (i.e., water retention characteristics, strength characteristics, permeability characteristics, microstructure) are introduced, as well as the source, viscosity, pH, and cost of these biopolymers. Then, based on the theory of unsaturated soil, the current research progress on the water retention characteristics of improved soil is summarized. The key factors affecting the strength of biopolymer-treated soil are introduced. Due to the actual environmental conditions, such as rainfall, the permeability and durability of biopolymer-treated soil are also worthy of attention. In summary, it is necessary to study the variation laws of the engineering properties of biopolymer-treated soil in the full suction range, and to predict such laws reasonably. The relevant results are conducive to the safer and more scientific application of biopolymers in geotechnical engineering practice.

Investigation of Soil Sample Using Triaxial Test and Detailed CBR Test

California Bearing Ratio (CBR) value of subgrade is utilized in accordance with IRC recommendation.in order to create flexible pavements. A crucial soil parameter for the design of flexible pavements and runways at airports is the California Bearing Ratio (CBR) value. It might also utilize to calculate the soil's subgrade reaction via correlation. It is among the most significant engineering characteristics of soil for designing road subgrade. CBR value is depend upon optimal dry density (MDD), maximum moisture content (MC), and other variables liquid limit (LL), plastic limit (PL), plasticity index (PI), moisture content (OMC), and type of soil, soil permeability, etc. Additionally, the soil's condition—whether it's damp or not—affects the value. The method of determining CBR is quite drawn-out and time-consuming. This study aims to link the soaked or unsoaked CBR value with the MDD, OMC, LL, PL, PI along with triaxial of various soil samples collected from Qila Road in Aligarh, Uttar Pradesh, India.

ECO-FRIENDLY SOIL STABILIZATION: A COMBINED APPROACH USING LIME AND WASTE EGGSHELL POWDER

<p>In recent years, geotechnical engineers preferred environmentally friendly and sustainable techniques to improve the engineering characteristics of expansive soil. This paper focuses on the comparative study of the enhancement in engineering properties of expansive soil using lime and waste eggshell powder. A series of laboratory tests such as Unconfined Compressive Strength Test, pH test, Free swell Index Test, Swelling Pressure Test, California – Bearing Ratio test and Atterberg’s limit test were performed for evaluating the engineering behaviour of expansive soil with lime and waste eggshell both individually and together. The experimental test results showed that the combined admixtures significantly improve the engineering characteristics of the soil. The maximum value of compressive strength at the inclusion of 9% lime and 12% waste eggshell powder was observed to be 306 kPa. The swell pressure of the treated soil showed up to a reduction till 2.32 at the inclusion of 3% lime and 12% waste eggshell powder. In all the tests, the combined admixtures exhibited greater efficiency when compared to individual inclusion of lime and waste eggshell. Thus, the investigation results confirmed the efficient use of lime and waste eggshell powder at optimum percentages as soil-stabilizing material and made them suitable for field applications.</p>

A REVIEW ON SOIL CONTAMINATION SOURCES: IMPACT ON ENGINEERING PROPERTIES AND REMEDIATION TECHNIQUES

Soil contamination produced by improper management of various petroleum and industrial products causes potential risks to the environment and soil engineering properties. Such contamination causes environmental deterioration and adversely affects soil engineering performance, altering almost all geotechnical properties. Several remediation techniques have been proposed to decontaminate the polluted soils. Choosing the best technique depends on both the energy consumption during operation and the treatment efficiency. The lack of a universally appropriate treatment method and the unavoidable expansion of contaminated land have justified the sake of reviewing the behavior of contaminated soils to develop both environmentally and geotechnically suitable soils for construction projects. The present paper reviewed some soil contamination sources’ backgrounds, effects, and remediation methods. Soils influenced by petroleum hydrocarbons and industrial effluents were evaluated. According to the reviewed studies, contaminants are evidenced to have a negative impact on soils' geotechnical characteristics by increasing settlement and swelling, reducing shear strength, and decreasing permeability. The need to restore the engineering characteristics of soils suggest the necessity to use remediation or stabilization technique. The electrochemical method, bioremediation, and stabilizing by additives are revealed to be efficient in improving the engineering properties and performance of contaminated soils.

Effect of Metakaolin on the Swelling and Shrinkage Behaviour of a highly Expansive Soil

Chemical stabilization of soil is essential for construction work because it improves engineering characteristics of soil, such as swelling soil stability. The main objective of the research is to investigate the impact of adding Metakaoline (MK) on the behavior of expansive soil to reduce swelling. Different amounts of Metakaoline, such as 2 %, 4 %, and 6 % of the weight of dry soil, are used to prepare the soil specimens. The engineering properties of the soil sample are examined using a variety of laboratory tests (consolidation, swelling potential, and liner shrinkage) original and treated soil at various mixing ratios to determine the swell potential and swelling pressure. The findings showed that the addition of MK has caused a reduction in the swelling reaching about 91% with 4% MK at 14 days, Also, the swelling pressure decreased from 110 kPa to 30 kPa with 4% Metakaolin.

Review of the Impact of geo-environmental toxicity on soil bearing pressure

Soil is a widely distributed naturally occurring material derived primarily from rocks and rocky minerals. Because soil is a natural product, it has some changeable and complicated characteristics by definition. When it comes to foundation design, the most important soil feature to consider while choosing a soil type is bearing pressure. The bearing capacity is one of the key soil properties required in foundation designs. How well a structure’s foundation performs depends on the nature and properties of the soil beneath it in relation to its capacity to withstand pressure. However, it is important to note that the bearing pressure of soils is affected by contaminants or pollutants in the geo-environment which produce a negative effect on the soil engineering characteristics.

Application of Analytical Hierarchy Process (AHP) for Landslide Hazard Analysis (LHA) in Kota Kinabalu area, Sabah, Malaysia

A very good Landslide Hazard Analysis (LHA) model was developed using the Analytical Hierarchy Process (AHP) method for the area of Kota Kinabalu, Sabah. The AHP is defined as theory of measurement through pairwise comparisons and relies on the judgements of experts to derive priority scales that measure intangibles in relative terms. The derived priority scales are synthesised by multiplying them by the priority of their parent nodes and adding for all such nodes. Weighted value of different spatial factors from the best models calculated with the AHP method were derived. The results showed that the geology (27% variance), geodynamic features (14% variance), slope conditions (26% variance), hydrology/hydrogeology (14% variance), types of land use (3% variance), and engineering characteristics of soils (8% variance), and rocks (8% variance) play an important role in landslide susceptibility analysis. In terms of Landslide Hazard Map (LHM), the analyses resulted of Kota Kinabalu area suggests that 2.78% of the area can be categorised as Very Low Hazard, 14.14% as Low Hazard, 19.74% as Moderate Hazard, 51.63% as High Hazard, 11.34% as Very High Hazard and 0.37% as Extremely High Hazard. Model accuracy assessment of LHA was performed using consistency ratio (CR) equal to 0.0129 (< 0.1) (acceptable) and 93.50 % accuracy of the validation prediction. Thus, the newly developed method works satisfactory and high reliability; and is applicable to further research development in Kota Kinabalu, Sabah, and potentially to expand with different environmental settings.

Stabilization of tropical soil using calcium carbide residue and rice husk ash

Many alternative stabilizers have been used in improving soil properties for road applications. However, they were mostly used to complement/partially replace cement or lime. This study seeks to use zero - cement/lime binders in the evaluation of engineering characteristics of soil stabilized with the best binary Calcium Carbide Residue (CCR) and Rice Husk Ash (RHA) treatment possible. The oxide compositions of the soil, CCR, and RHA were determined. The natural soil was subjected to index property tests), compaction, Soaked California Bearing Ratio (SCBR), Unconfined Compressive Strength(UCS), and erodibility. To achieve optimal CCR: RHA ratio, compaction and CBR were used. Atterberg limits, compaction, SCBR, Unconfined Compressive Strength, and erodibility were used to evaluate the engineering performance of the soil stabilized at 2, 4, 6, 8, 10% of the optimum CCR: RHA mix. The RHA is a class N pozzolan while the CCR's CaO of 61% indicates how cementitious the residue is. The soil sample is non-lateritic. CCR: RHA combined ratio of 40:60% offered the best strength and compaction performances. Further, the addition of the optimum CCR: RHA at 2, 4, 6, 8, 10% improved the soil's Plasticity Index (PI). Only 8% addition had a Maximum Dry Density (MDD) of 1770 kg/m3 meeting the AASHTO standard. The addition of CCR: RHA improved the soil's strength properties in terms of UCS and CBR. However, the CBR values generally do not meet the FMWH and AASHTO recommendations for subgrade. Erodibility behaviour showed that increasing CCR and RHA content improves soil durability. CCR and RHA have undoubtedly increased soil strength, but not to the desired level. Therefore, further research should be conducted to determine their compatibility with other stabilizers.

The Effect of Both Moisture and Clay Content on The Soil Corrosion Process for Different Periods of Time as A Geomorphological Study in Al-Kut City

Soil corrosion is a major hazard to subterranean infrastructure including gas and oil transmission pipes, underground storage tanks and others. The impacts of soil engineering characteristics on buried mild steel coupons’ metal loss are investigated in this work. Soil characteristics such as soil clay and moisture content are the focus of the present research in Al-Kut city near Tigris River. For a twelve month period, 100 pieces of mild steel coupons were put underground in five different sites across to look into the effects of the aforementioned variables on loss of metal owing to corrosion of soil. Every three months, the samples were recovered to evaluate the rate of weight loss and corrosion rate development. The data show that the high moisture content of the soil is linked to rapid corrosion development. Corrosion on clay soil, on the other hand, takes longer to start. According to the qualitative assessment, soil moisture content has a greater impact on corrosion dynamics than clay content.

Strength performance and microstructural evolution of carbonated steel slag stabilized soils in the laboratory scale

The technique of carbonated stabilization is an innovative method to improve the engineering performance of soft soils. However, the improvement in the engineering performance of stabilized soils with carbonized steel slag has not been studied. In addition, the effect of clay minerals on carbonation parameters and D-W cycle performance remains unknown. To this end, in this paper, three types of synthetic soils containing different clay minerals were prepared to be stabilized by carbonated steel slag. The strength performance and microstructural evolution of carbonated steel slag stabilized soils were investigated by drying-wetting (D-W) cycle tests, unconfined compression strength (UCS) tests, X-ray diffraction (XRD), thermogravimetry (TG), and scanning electron microscopy (SEM). The results showed that the compressive strength after and resistance to D-W cycles of carbonated steel slag stabilized soils were significantly improved due to carbonation treatment. The presence of clay minerals in stabilized soils led to the high values of optimum moisture content for carbonation (C-OMC). The C-OMC value of stabilized soils containing montmorillonite was higher than that of stabilized soils containing kaolinite. Montmorillonite had a higher negative effect on the D-W cycle performance of soils compared to kaolinite. This fact could be reflected by the fluctuation of UCS and mass change ratio (Rm). The main carbonation product by three types of carbonated steel slag stabilized soils was calcite, which remained stable after D-W cycles. After carbonation for 18 h, the generated calcite and carbonation degrees for three types of stabilized soils were obtained. In the microstructures of carbonated steel slag stabilized soils, the spindle-like clusters of the generated calcite appeared, which adhered to the surface of mineral particles. The aggregated degrees of the generated calcite in stabilized soils containing clay minerals tended to decrease after D-W cycles. In this work, a new type of carbonated steel slag stabilized soil was studied. The results indicated that the effect of clay minerals on the engineering characteristics of soil should be considered.

Engineering characteristics of soil stabilised with saw dust ash and cement

ABSTRACT The study herein investigates the performance of Saw Dust Ash (SDA) in combination with cement for soil stabilisation. Performance of SDA is studied with respect to compressive strength, shear strength, penetration and deformation responses. For a certain cement content, the compressive strength reaches a maximum value with the increase of SDA and the corresponding SDA content is defined as the optimum content. Optimum SDA content varies within 6–12% based on the percent of cement added. When optimum amount of SDA is added, 28 days’ compressive strength of 2406–5625 kPa was achieved for varying amount of cement (3–7%). The mechanical response is illustrated using microstructural observations. Results from direct shear tests revealed that with the inclusion of 6–15% SDA with cement, improved shear strength parameters (cohesion, angle of internal friction) can be obtained; an angle of internal friction as high as 40 was achieved herein. Compression index can be reduced by 32–41% compared to unstabilised soil if optimum amount of SDA-cement is added. It is concluded that considering compressive strength, shear strength, penetration resistance and compressibility, SDA can effectively be used along with cement for stabilisation of clay soil.

Evaluation Of Use of Stone Column in Unengineered Closed Landfill Soil

In the building industry, ground improvement techniques based on stone column are widely employed. It is a very successful approach for enhancing the engineering characteristics of soil in all aspects, as well as reducing the settling issue in poor-grounded soils including silt, clay, silty sand, and organic soil. The performance of stone columns, is determined by the confining pressure provided by the surrounding soils. Engineering constructions built on thick layers of soft soil strata face issues such as limited bearing capacity, excessive total and differential settlement, lateral spreading, and so on. To address such issues, many ground improvement techniques are available. In exceptionally soft soils, the lateral confining pressure may be inadequate, resulting in column bulging failure. Individual stone column encasement improves lateral resistance to bulging by adding restricting pressure. This research focuses on the geotechnical aspects of building on closed landfill sites. A total of 33 models were tested in a geotechnical engineering laboratory on virgin former landfill soil and stone column with and without encasement in this current study. The increased diameter, length and L/D ratio of the column has demonstrated that the load capacity has increased and soil settling has decreased. When an unreinforced stone column has been installed, the ultimate bearing capacity of landfill soil is increased by 75-112.50 per cent and 87.50-176 per cent respectively, for 10mm and 20mm diameter stone column. Furthermore, when a fully reinforced stone column has been installed, it had increased by 156.25-212.50 per cent and 200-298 per cent for 10mm and 20mm diameters respectively. The stiffness of soil is increased by the stone column, which contributes to increase in the load capacity. The geogrid layer confines an aggregate, which contribute to enhance shear stiffness and bearing capacity.

Laboratory Investigation on Physical-Mechanical Characteristics and Microstructure of a Clayey Gypsiferous Soil in the Presence of Chemical Accelerator

Gypsiferous soils are considered as problematic soils that cause damage to engineering infrastructures, particularly hydraulic structures. The exposition of gypsiferous soils to the steady flow leads to the dissolution of gypsum particles, significantly changing the soil engineering characteristics. In this paper, by employing physical, chemical, and mechanical experiments, the effect of raw gypsum with various percentages (0%, 3%, 6%, 9%, 12% and 15%) on the geotechnical parameters of a low plasticiy clay was investigated through leaching. Electrical conductivity test and ionic concentration analysis were used to assess the trend of gypsum dissolution. The results showed that leaching and increased gypsum content significantly degraded soil engineering characteristics, such as strength and compressibility. Acidic accelerator (diluted acetic acid) speeded up the chemical reaction rate and, at the same time, affected the geotechnical properties of the soil more than water. Mineralogical and microstructural studies (x-ray diffraction, scanning electron microscopy and energy-dispersive x-ray spectroscopy) were carried out to evaluate the interaction between gypsum and soil particles and verify laboratory test results. The x-ray diffraction patterns indicated the formation of new peaks such as calcium aluminate hydrated (CAH) and calcium silicate hydrated (CSH) and the altered structure of pure soil following the addition of raw gypsum. Scanning electron microscope images confirmed the presence of cementitious compounds and changes in the texture of gypsiferous soil in comparison with pure soil. Energy dispersive x-ray interpretation revealed changes in the chemical composition of soil blended with gypsum. The laboratory test results were corroborated by microstructural analyses.

Effect of freeze-thaw cycles on soil engineering properties of reservoir bank slopes at the northern foot of Tianshan Mountain

The instability of soil bank slopes induced by freeze-thaw cycles at the northern foot of Tianshan Mountain is very common. The failure not only caused a large amount of soil erosion, but also led to serious reservoir sedimentation and water quality degradation, which exerted a lot of adverse effects on agricultural production in the local irrigation areas. Based on field investigations on dozens of irrigation reservoirs there, laboratory tests were carried out to quantitatively analyze the freeze-thaw effect on the soil engineering characteristics to reveal the facilitation on the bank slope instability. The results show that the softening characteristics of the stressstrain curves gradually weaken, the effective cohesions decline exponentially, the seepage coefficients enlarge, and the thermal conductivities decrease after 7 freeze-thaw cycles. The freeze-thaw effect on the specimens with low confining pressures, low dry densities and high water contents is more significant. The water migration and the phase transition between water and ice result in the variations of the soil internal microstructures, which is the main factor affecting the soil engineering characteristics. Sufficient water supply and the alternation of positive and negative temperatures at the reservoir bank slopes in cold regions make the water migration and phase transition in the soil very intensely. It is easy to form a large number of pores and micro cracks in the soil freezing and thawing areas. The volume changes of the soil and the water migration are difficult to reach a dynamic balance in the open system. Long-term freeze-thaw cycles will bring out the fragmentation of the soil particles, resulting in that the micro cracks on the soil surfaces are developing continuously. The soil of the bank slopes will fall or collapse when these cracks penetrate, which often happens in winter there.

MDD & OMC of Black Cotton Soil Reinforced with Randomly Distributed Banana Fibers

Expansive soil causes serious problems on civil engineering structures in arid and semi-arid climate regions of the world. Such soils, swell during rainy season and shrink in summer season. In India, expansive soil includes almost the entire Deccan plateau, and causes damage to buildings, roads, pipelines, and other structures every year. The black cotton soil had improved by various methods to enhance the engineering characteristics of soil. However, due to various issues such as leaching, release of mineral, these methods are not sustainable. Hence, an attempt had been made to improve black cotton soil characteristics by using the waste material such as banana fiber. In the present study, the experiments were conducted to understand the density & moisture content of soil by reinforcing the soil with randomly distributed banana fibers. The laboratory tests were conducted on locally available black cotton soil. The banana fiber were added to the soil in varying percentages of 0.0 %, 0.50 %, 1.00 %,1.5 % and2.00 % and in varying lengths of 1 cm,2cm and 3 cm randomly. The standard Proctor tests were conducted to study its effect of banana fiber on dry unit weight and OMC. It was observed that MDD is decreasing and OMC is increasing with increase in % of fibers and length of fiber.