Improvement Of Expansive Soil Research Articles

Dynamic Behavior of Rubber Fiber-Reinforced Expansive Soil under Repeated Freeze–Thaw Cycles

Large volumes of waste tires are generated due to the rapid growth of the transportation industry. An effective method of recycling waste tires is needed. Using rubber from tires to improve problematic soils has become a research topic. In this paper, the dynamic response of rubber fiber-reinforced expansive soil under freeze–thaw cycles is investigated. Dynamic triaxial tests were carried out on rubber fiber-reinforced expansive soil subjected to freeze–thaw cycles. The results showed that with the increase in the number of freeze–thaw cycles, the dynamic stress amplitude and dynamic elastic modulus of rubber fiber-reinforced expansive soils first decrease and then increase, and the damping ratio first increases and then decreases, all of which reach the turning point at the 6th freeze–thaw cycle. The dynamic stress amplitude and dynamic elastic modulus decreased by 59.4% and 52.2%, respectively, while the damping ratio increased by 99.8% at the 6th freeze–thaw cycle. The linear visco-elastic model was employed to describe the hysteretic curve of rubber fiber-reinforced expansive soil. The elastic modulus of the linear elastic element and the viscosity coefficient of the linear viscous element first decrease and then increase with the increase in the number of freeze–thaw cycles; all reach the minimum value at the 6th freeze–thaw cycle. The dynamic stress–dynamic strain curve calculation method is established based on the hyperbolic model and linear visco-elastic model, and the verification shows that the effect is better. The research findings provide guidance for the improvement of expansive soil in seasonally frozen regions.

Soil-water retention capacity of expansive soil improved through enzyme induced carbonate precipitation-eggshell powder

Enzyme Induced Carbonate Precipitation (EICP) has been extensively investigated as a promising approach to improve engineering properties of soil, while Eggshell Powder (ESP) is an agricultural waste that effectively fills soil pores. The ESP provides abundant nucleation at sites for the EICP process, further promoting the effective precipitation of calcium carbonate. The research presented in this paper investigated the Soil Water Characteristic Curves (SWCC), permeability coefficient, and microstructure of expansive soil before and after EICP and EICP+ESP modification. A series of laboratory experiments were conducted, including soil water characteristic tests, permeability tests and Scanning Electron Microscopy (SEM). The results proved that the addition of EICP and EICP+ESP into natural expansive soil resulted in a gradual decline in air entry value, residual water content, and permeability coefficient, indicating an increase in water retention capacity and a decrease in permeability. Furthermore, with the intrusion of EICP and EICP+ESP, the contact between particles becomes smoother, and the soil pores become more equally distributed. Ultimately, there was an enhancement in water retention capacity of the natural expansive soil. This study emphasizes the synergistic potential of combining EICP and EICP+ESP as stabilizing additives to enhance the water retention capacity of expansive soil. Moreover, the reuse of ESP provides a sustainable solution for the resource utilization of agricultural waste and the improvement of expansive soil using bio-inspired methods.

Improvement of expansive soil by microwave irradiation

Improvement of expansive soil by microwave irradiation

Expansive soil improvement using industrial bagasse and low-alkali ecological cement

Cement is the primary material used for mitigating expansive soil hazards due to its easy availability and relatively low cost. However, the most commonly used ordinary Portland cement renders the soil strongly alkaline after treatment, and the development of cracks in the soil is not effectively controlled under the influence of wet-dry cycles following cement stabilization. These two drawbacks significantly impact both the ecological environment and the strength of the cement-stabilized expansive soil. This study innovatively proposes an improvement to the method of cement stabilization of expansive soil by incorporating low-alkali ecological cement and industrial sugarcane bagasse (a byproduct of sugar production). After assessing the basic physical properties of the expansive soil, it was improved by mixing with industrial bagasse and low-alkali ecological cement. Through experiments on dry-wet cycles, soil-water characteristic curve tests, direct shear tests, and electron microscopy scans, we explored the enhancement of the expansive soil. Our focus was on the development of cracks, soil moisture migration patterns, changes in shear strength, and microstructural alterations. The following conclusions were drawn from the experiments: i. Compared to the method of ordinary Portland cement stabilization, the pH of expansive soil improved by low-alkali ecological cement combined with industrial sugarcane bagasse is more suitable for plant growth. ii. The unique tubular structure of industrial sugarcane bagasse provides elastic space for soil deformation, inhibiting the development of soil cracks. iii. The water retention capacity of expansive soil significantly increases after improvement with low-alkali ecological cement and industrial sugarcane bagasse. Within the range of matrix suction for plant growth, soil moisture changes more slowly, providing a more stable water supply for plants. iv. The combination of 1.2% industrial sugarcane bagasse and 7% low-alkali ecological cement exhibits the highest shear resistance, maintaining strength exceeding that of untreated expansive soil after five wet-dry cycles. v. SEM analysis confirms the effectiveness of industrial sugarcane bagasse and low-alkali ecological cement in improving expansive soil. This study improved the widely used cement stabilization method for expansive soil in practical engineering applications. Additionally, it introduced an additional utilization pathway for industrial bagasse residue waste. This research provides a new direction and reference for the combination of waste utilization and natural disaster management in the treatment of expansive soil hazards.

Identification of the influence of electrokinetic soil improvement on the microstructure, physical and mechanical properties of expansive soil

Clay is a soil with low permeability. Clay is considered a problematic soil besides peat soil. The main problem with clay is its mineralogy. Expansive clay soils contain the minerals kaolinite, illite, and montmorillonite. Montmorillonite has weak bonds between its layers. These weak bonds make the soil easily incorporated, one of which is water. Water approaching expansive soil will bond with it and cause swelling. Expansive soil improvement studies have been conducted. One of them is electrokinetic. Expansive soil from Karawang, Indonesia is one of the soils with a high swelling index. This is because montmorillonite is inside. The Karawang expansive soil will be improved by flowing several salt solutions with various voltages. The applied voltage will flow the solution from the cathode to the anode and fill the clay minerals. Four voltage variants will be applied with the same electrokinetic application time. The mineralogy of soil before and after electrokinetic improvement undergone changes. The changes can be seen from SEM and XRF testing. The improved soil changed its physical properties from clay with high plasticity to clay with low plasticity. Chemical elements from salt solution trap in montmorillonite then make positive changes in soil mineralogy, soil physical properties, and mechanical properties. The mechanical properties can be seen in a decrease in the C value and an increase in the soil angle of friction after electrokinetic improvement. After electrokinetic improvement using calcium chloride, the lowest soil cohesion value was 12.356 kg/cm2 at 12 V. After electrokinetic improvement with calcium dioxide, the lowest cohesion value at 12 V voltage is 19.22 kg/cm2. In barium sulfate solution, the lowest soil cohesion at 15 V is 12.16 kg/cm2. The soil swelling value decreased after improvement with calcium chloride to 0.008 % from 0.027 %. The research results in calcium chloride with 12 V give optimized results on soil improvement with electrokinetics

Voltage optimization in expansive soil improvement with saline solution on swelling and shear strength

One of the problems in the construction of the road network is the presence of expansive clay and loose soil. In Java, expansive clays are generally the result of weathering rock formations including shale and clay, while soft soils are derived from unconsolidated sedimentation. In situ stabilization of clay with chemical solutions will be difficult due to the very low permeability of the soil. Some researchers exploit the phenomenon of electrodynamics, the nature of the electric and hydraulic coupling to reform clay. This paper examines the experimental results of clay reclamation in the laboratory. The study was carried out on clay from Karawang, West Java province, Indonesia, which was injected with saline solution and used different voltages of 12V, 15V, 18V, and 24V. The success of this experiment will be seen by comparing the mechanical properties of the soil before and after electrochemical spraying. The test results show that electrochemical injection with calcium chloride salt solution and a voltage of 15V can reduce swelling characteristics and increase optimal shear strength.

Expansive Soil Improvement Using Electrochemical Injection

According to the Geological Map of Indonesia, the distribution of espansive soils in Indonesia, especially in Sumatra and Java, is very large. These soils, which have the mineralogy of illite, kaolite and montmorillonite, are known to have very high growth properties that affect the bearing capacity of the soil. Due to the mineralization nature, swollen soil is easy to retain water during the rainy season, leading to swelling and conversely, it is easy to shrink in summer. Therefore, Indonesia with its hot and rainy season has a great influence on the land expansive. Along with the increase in road construction through the Strategic National Highway Projects, it is likely that the project will be located in the expanded land area. Therefore, it is necessary to have measures to improve the soil to increase the shear strength of the soil. The bearing capacity of the soil can be determined from one of the values of the shear resistance of the soil. West Java is one where there are many types of soil. While this area is included in a national strategic project, namely the construction of the Ja-Pek II toll road. Soil improvement measures are taken to improve soil properties in order to increase the bearing capacity of the soil. Chemical soil electrolysis is an alternative method that can be used, with chemical solutions that are not harmful to the environment. The aim of this study was to determine the improvement in the bearing capacity of swollen soils that were improved by electrochemical spraying by examining one of the soil mechanical properties.

Applicability of Soybean Crude Urease-Calcite Precipitation (SCU-CP) Method for Improvement of Expansive Soil

Expansive soil is one of the problematic soils that can swell and shrink, causing damage to buildings. Expansive soil needs improvement before being used for buildings. The typical method for expansive soil improvement is mixing soil with additives such as cement, lime, and fly ash. However, mixing additives like cement, lime, and fly ash is not easy to distribute evenly and negatively impacts the environment. Soybean Crude Urease-Calcite Precipitation (SCU-CP) is a soil improvement method currently being developed. SCU-CP is easier to apply in the field and more environmentally friendly than the common method. SCU-CP method was proven to impact sandy soil and peat soil significantly, but SCU-CP’s impact on expansive soil still needs to be discovered. This study aims to know the effects of SCU-CP on soil swelling parameters and determine the optimum reagent concentration for expansive soil improvement using SCU-CP. This study used three reagent concentrations (1.0 mol/L, 1.5 mol/L, and 2.0 mol/L) and one control sample (without SCU-CP). The swell percentage decreased by 2 – 3% after SCU-CP treatment, but adding reagent concentration did not significantly reduce the swell ratio. Swell pressure did not decrease after SCU-CP treatment. Swell pressure was only reduced by 7.92 kPa with 1.0 mol/L reagent of SCU-CP, while the other concentration swell pressure tended to be increased. This study’s optimum reagent concentration for expansive soil improvement is 1.0 mol/L.

Micro-analysis Tanah Ekspansif yang Diperbaiki Secara Kimiawi

Road construction on expansive soil faces many problems such as deflection, longitudinal cracks, circular cracks and spreading cracks in road construction due to the large nature of swelling and shrinkage. This study aims to identify changes in the mineralogy microstructure and chemical properties of the soil in chemically corrected expansive soils so that solutions for expansive soil improvement are obtained by utilizing local materials based on industrial waste, namely Fly ash and Waste Foundry Sand. The research method is in the form of laboratory experiments, namely Structure Electron Microscope and XRD tests on native soil and soil stabilized with Fly ash and Waste Foundry Sand to analyze mineral structure and chemical changes. The results of the analysis found that the effect of the two types of additives on expansive soils was descriptively significant. The addition of fly ash and WFS to the soil makes the pores and cracks filled with fly ash particles and some form of hydration. After the addition of Fly ash and WFS, ion exchange and pozzolanic reactions from fly ash occur to make the flake and flocculant structure of the soil cement into a crystal or block structure, thereby increasing the compactness and integrity of the soil sample.

Recent advances in expansive soil stabilization using admixtures: current challenges and opportunities

Expansive soils are problematic for direct engineering applications in their natural state because of the shrink-swell phenomenon. Numerous stabilizers and methods have been used to stabilize expansive soils as an effort to make them more practical for construction purposes. Searching for suitable soil stabilizers to overcome difficulties caused by the expansive soils is the key issue, not only in terms of achieving the required soil geotechnical characteristics but also in terms of environmental and economic concerns. The purpose of this article was to assess the current trends, challenges, and opportunities of various admixtures utilized for expansive soil improvement, as well as their economic and environmental consequences. A critical review of various admixtures commonly used as soil stabilizers, including marble waste powder, fly ash, eggshell powders, stone waste, and lime powder is conducted. Furthermore, a the review was also focused to analyze the offered stabilizers in terms of soil geotechnical properties and sustainability in the field application.

Orthogonal Experimental Study on Crack Resistance of Biochar and Sisal Fiber Composite Improved Expansive Soil

Desiccation shrinkage is a key factor contributing to the engineering hazards in expansive soil. To inhibit the initiation and expansion of cracks, a composite improvement approach using biochar and sisal fibers was applied to expansive soil from Nanning, Guangxi. An orthogonal test method was employed to conduct desiccation cracking tests on the improved soil, investigating the effects of biochar and sisal fibers on crack length, crack ratio and crack width. The results indicate that different proportions of sisal fibers and biochar can effectively inhibit soil crack development. The biochar content is the primary factor affecting crack length, while sisal fibers mainly inhibit the development of crack ratio and average crack width. The optimal proportion for composite improvement approach was found to be 6‰ of 3 cm sisal fibers and 4% biochar. The study findings can provide a new approach for the expansive soil improvement and for controlling engineering problems caused by soil cracking.

Experimental Study on the Influence of Microbial Content on Engineering Characteristics of Improved Expansive Soil

In order to study the influence of microbial content on the engineering properties of expansive soil im-proved by microbially induced calcium carbonate (MICP) method, and to clarify its influence law and mechanism of action, and to provide some theoretical reference for the application of MICP method to expansive soil treatment. Microbial reproduction and their mineralization in expansive soils have been studied. The problems such as moisture content controlling and low calcium content in the process of treating expansive soil with MICP method have been solved by means of adding calcium salt and using optimum moisture content as the control standard of the total amount of bacterial solution and cementation solution. The tests such as compaction, swelling rates and triaxial shear are carried out. The hydrophilicity, compaction, expansibility and strength characteristics of improved expansive soil under different microbial content are analyzed. The results demonstrate that with the increasing of microbial content, the dry density and shear strength of the improved soil are first increased significantly and then tend to be stable gradually. At the same time, the hydrophilicity and expansibility of improved soil are all decreased significantly. The microstructures of improved expansive soil are imaged by scanning electron microscope. Analytic results show that soil particles have been cemented and the pores in the soil have been filled due to microbially induced calcite precipitation. As a result, microstructure characteristics of the soil have been improved. From the microscopic point of view, the improvement mechanism of MICP method on expansive soil has been revealed. The conclusions above laid a theoretical foundation for in-tensive study on the improvement of expansive soil by MICP method. It also provides a new idea for perfecting and expanding the engineering application of expansive soil improvement technology.

Re-utilization of Stone Industry Waste Materials for Stabilization of Expansive Soil

This research paper depicts the experimental investigation of the impact of stone dust as an admixture on the geotechnical characteristics of expansive soils that shrink and swell during the wet and dry seasons. As a result, expansive soil causes the differential settlement of structures. Thus the stabilization of expansive soil is important to overcome potential pavement failure. For this purpose research studies were carried out on the reuse of stone industry wastage for the improvement of expansive soil. Also, this research is beneficial to utilize the stone dust waste for strengthening the soil and making the environment pollution-free. Stone dust was used to stabilize the geotechnical characteristics of the weak soil such as shear strength, unconfined compressive strength (UCS), index properties, maximum dry density (MDD), optimum moisture content (OMC), and California bearing ratio (CBR). The percentages of stone dust employed in the studies were 0%, 7%, 14%, 21%, and 28% by dry weight of soil, which substantially reduced the soil's swelling properties. The results show significant improvements in the desirable geotechnical characteristics of the expansive soil. The optimal quantity of stone dust was concluded based on the findings for treating the subgrade of weaker expansive soil.

Improvement of expansive soil using granulated scrap tires

Improvement of expansive soil using granulated scrap tires

Optimization of Multi-additives for Expansive Soil Improvement Using Response Surface Methodology

Optimization of Multi-additives for Expansive Soil Improvement Using Response Surface Methodology

Laboratory Study on Improvement of Expansive Soil by Chemically Induced Calcium Carbonate Precipitation

This paper proposes the use of calcium carbonate (CaCO3) precipitation induced by the addition of calcium chloride (CaCl2) and sodium carbonate (Na2CO3) solutions as a procedure to stabilize and improve expansive soil. A set of laboratory tests, including the free swell test, unloaded swelling ratio test, unconfined compression test, direct shear test, scanning electron microscopy (SEM) test, cyclic wetting–drying test and laboratory-scale precipitation model test, were performed under various curing periods to evaluate the performance of the CaCO3 stabilization. It is concluded from the free swell tests and unloaded swelling ratio tests that the addition of CaCl2 and Na2CO3 can profoundly decrease soil expansion potential. The reduction in expansion parameters is primarily attributed to the strong short-term reactions between clay and stabilizers. In addition, the formed cementation precipitation can decrease the water adsorption capacity of the clay surface and then consequently reduce the expansion potential. The results of unconfined compression tests and direct shear strength tests indicated that the addition of CaCl2 and Na2CO3 has a major effect on geotechnical behavior of expansive soils. Based on the SEM analyses, new cementing crystalline phases formatted by sequentially mixing CaCl2 and Na2CO3 solutions into expansive soil were found to appear in the pore space, which results in a much denser microstructure. A laboratory-scale model test was conducted, and results demonstrate the effectiveness of the CaCO3 precipitation technique in stabilizing the expansive soil procedure. The test results indicated that the concentration of CaCl2 higher than 22.0% and Na2CO3 higher than 21.2% are needed to satisfactorily stabilize expansive soil. It is proposed to implement the precipitation technique in the field by the sequential permeation of CaCl2 and Na2CO3 solutions into soils in situ.

Experimental Study on Physical-Mechanical Properties of Expansive Soil Improved by Multiple Admixtures

The treatment of expansive soil is always a difficult problem in engineering. Using coal gangue, fly ash, and other solid waste to treat expansive soil has gradually become a new way of energy saving and environmental protection. Most of the existing studies focus on using one or two kinds of admixtures to improve expansive soil, but there are few studies on improving expansive soil with multiple admixtures. In this paper, the expansion and shrinkage deformation and strength characteristics of expansive soil modified by coal gangue, fly ash, and lime are studied experimentally. Nine groups of different mixing schemes were designed through orthogonal tests, and the physical and mechanical properties of the improved expansive soil under different mixing ratios were tested. The sensitivity analysis of the test results was carried out to study the effect of each admixture on the improved expansive soil under different mixing ratios, and the optimal mix ratio under different conditions was obtained. The optimal mix ratio is 8% for coal gangue, 11% for fly ash, and 6% for lime. Further scanning electron microscopy (SEM) tests were carried out to analyze the microstructure of the improved expansive soil and explore the improvement mechanism of the multiadmixture. The results show that the optimal moisture content and the maximum dry density of the expansive soil with ash are decreased, and the properties of liquid plastic limit, free expansion rate, shear strength, and unconfined compressive strength of the expansive soil are improved obviously. Through the analysis of the comprehensive balance method, it is found that the content of lime has the greatest influence on the improvement effect of expansive soil, followed by that of coal gangue, and the least is that of fly ash. SEM structure analysis reveals that the particles of improved expansive soil are mainly aggregates, the soil structure is dense, particle agglomeration increases, and the overall structure is stronger. The research results can provide reference for the improvement of expansive soil with various admixtures and the resource utilization of coal gangue, fly ash, and other solid wastes.

Utilization of Lime Sludge Activated by Salt in Egyptian Expansive Soil Improvement

Expansive soils are active clays which cause engineering problems all over the world. This research deals with the impact of lime sludge (LS) as industrial solid waste from sugar-cane factory and sodium chloride salt (NaCl) on engineering properties of expansive soil. In this research, an analytical study of chemical and physical properties of Egyptian expansive soil in Sixth of October City was made as a case study. The laboratory results showed improvement of chemical, microstructural properties and thus the engineering properties of this soil. The results of chemical analysis showed the ability of soil to improve pH; soil alkalinity raise to the required level of stabilization. After soil treatment, Microstructure scanning electron with energy dispersive spectroscopy (SEM-EDX) analyses showed that new cementitious compounds are formed and soil was changed from a weak dispersed structure to strong flocculated structure. It was also observed by increasing LS and NaCl concentrations the plastic limit increased and the liquid limit decreased, hence decreased plasticity index; the rate of soil free swelling is decreased due to change of expansive soil texture. Therefore, lime sludge activated by NaCl has positive effects on engineering properties of soil. By this way we protect the environment from industrial solid wastes.

Influence of Rock Powder on the Geotechnical Behaviour of Expansive Soil

Expansive soils create challenges in civil engineering projects due to their tendency to significant volume changes with variation in moisture content. In this study, an experimental study was carried out to evaluate the influences of rock powder on the geotechnical properties of expansive soil. This paper presents the results of some index and engineering properties of expansive soil mixed with the rock powder, including Atterberg limits, compaction, free swelling, unconfined compressive strength (UCS), California bearing ratio (CBR), direct shear, and permeability at different percentages (0%, 8%, 16%, 24%, 32, and 40% by dry soil weight). The results reveal that the index properties, optimum moisture content, free swelling, cohesion, and coefficient of permeability decrease with the addition of rock powder up to 40%. Whereas, the maximum dry density, UCS, and CBR increase up to 24% of rock powder thereafter reversed. Furthermore, the internal friction angle increases by 95.32%, while the subbase thickness layer for a roadway could be reduced by 40% with the addition of 40% rock powder to the soil samples. Based on the test results, the optimum ratio of rock powder for the improvement of expansive soil is about 24%.

Improvement of Expansive Soil by Using Micro Silica Fume

Expansive soil shows frequent volume changes with the changes in the moisture content, causing severe problems to the civil engineering structures. Consequently, the measurements of swelling properties including free swell index and swelling pressure are extremely important. Several attempts are being made all over the world to control the swell-shrink behavior of expansive soils. Many researches have investigated how to overcome the problems of such soils by means of using different additives such as cement, lime, steel fibers, stone dust and fly ash. This study is directed towards the improvement of expansive soil with a new, inexpensive and environmentally friendly additive. In this study, the effect of using micro silica fume to stabilize the soil was investigated through a laboratory study. Test results showed that, the micro silica fume can considerably decrease the free swell index value by 69% at 25% micro silica fume content. Also, the swelling pressure is reduced from 410 kN/m2 to nearly 330 kN/m2 and 302 kN/m2 at micro silica fume content of 5% and 25%, respectively. This demonstrates the effectiveness of the proposed addition in the expansive soils improvement. This improvement technique can be used in different civil engineering construction projects including slope stabilization and road embankments.