Chemical Soil Stabilization Research Articles

Chemical and Mechanical Soil Stabilization Techniques for Foundations

Introduction: The geotechnical study is crucial for foundation design and herein the feasibility of stabilizing soil from Quillollaco Formation in Loja, Ecuador with quicklime. Methodology: Laboratory tests followed ASTM standards. Unaltered soil samples were extracted at depths ranging from 2,00 to 3.00 m and fed quicklime at varying percentages (13,00 to 21,00% and 3,00% for quicklime) during curing periods of 7 to 28 days. Before obtaining results, the soil was classified by primary classification. Laboratory tests included Atterberg limits, Standard Proctor, unconfined compressive strength and permeability. Results: Consequently, the results indicated that the soil is primarily clay with low plasticity. Although the addition of quicklime increases plasticity and compressive strength, the improvement is minimal and varies with dosage and cure time. Greater compaction and workability are observed with lower quicklime contents. Regarding permeability, moderate to high improvement is recorded with quicklime addition, suggesting enhanced drainage capacity. Disscusion: Stabilization of quicklime soil may improve some geomechanical properties, but its effectiveness and profitability could be limited, especially in clay soils of low plasticity. Emphasis is placed on the need to consider soil stabilization alternatives that are efficient and sustainable from economic and environmental points of view.

Shear Strength and Durability of Expansive Soil Treated with Recycled Gypsum and Rice Husk Ash

Expansive soil underlying structures pose a significant risk to the integrity of superstructures. Chemical soil stabilization can be used to strengthen soils due to the cost and impracticality of mechanical approaches. Waste materials such as recycled gypsum and rice husk ash have been considered alternatives because of their sustainable and economic advantages. A combination of these additives was used to address the high absorption of gypsum and the lack of cohesion of the pozzolan. The study assessed the short-term and long-term performance of expansive soil treated with recycled gypsum and rice husk ash under normal and fluctuating moisture conditions. Direct shear tests indicated ductile and compressive soil behavior with improved shear strength. A good approximation of stress–strain response was made with a modified hyperbolic model for treated soils that exhibited strain hardening and compressive volumetric strain. Durability and water immersion tests were performed for samples after varying curing periods and cycles of capillary soaking to assess the behavior when exposed to varied environmental conditions. Samples under the modified durability test experienced significant strength loss, with decreasing compressive strength as curing durations increased. Specimens in the modified water immersion test experienced significant strength loss; however, it was determined that curing durations did not contribute to the change in the strength of the sample. Expansion index tests also determined that the treatment effectively mitigated expansivity and collapsibility in all samples. Despite improvement in shear strength and expansion potential, further investigation is needed to enhance the durability of soil treated with gypsum and rice husk ash.

EFFECT OF USING LIME AND FLY ASH AS A CEMENT SUBSTITUTE FOR SOIL STABILITY

Subgrade is the lowest layer that receives the load on it if it does not have carrying capacity that is allowed then need for soil stabilization. Chemical soil stabilization is often done with the addition of cement but the use of cement material will cost quite high, it is necessary to alternate other materials for the substitution of cement to reduce the implementation costs incurred. Cement will be replaced as a stabilizing material in this research with additional materials like lime and fly ash. In this research, soil material was taken from the Sentul – Karawang Toll Road Project STA 24+300, with fly ash from PT PUSRI as the stabilization material, and lime material obtained from the market in Yogyakarta. The stabilization material will be used with a fixed lime percentage of 4.2% of the dry weight of the soil, and fly ash at 1.4%, 2.1%, 2.8%, 3.5%, and 4.2% of the dry weight of the soil. The soil samples were tested for physical and mechanical properties, including Standard Proctor and California Bearing Ratio (CBR). All test results were compared to select one variation, which was then designated as the Optimum Mix Design (OMD) sample. The test results of the soil sample + 4.2% lime + 2.1% fly ash yielded a CBR value of 15.52%, indicating an increase of 1078.02% from the initial 1.44%, and were formally designated as an OMD sample. The CBR value satisfies the subgrade requirements, namely >6%.

Performance of Nickel Slag as a Stabilization Material for Soft Soil

The chemical soil stabilization method is an effort to improve soil bearing capacity according to soil work specifications in construction. The use of conventional stabilization materials, such as cement and lime, is considered environmentally unfriendly. Utilizing by-products from the mining industry becomes an alternative that can be developed in soil improvement efforts. This research aims to examine the influence of nickel slag on the enhancement of soil bearing capacity as observed through its unconfined compressive strength value. In this study, the concentration of added nickel slag as a stabilization material is 3%, 6%, 9%, and 12% by dry soil weight. The test specimens used are cylinders with a diameter of 5 cm and a height of 10 cm. Unconfined compressive strength testing is conducted after the specimens are cured for 14 days. The results of this study indicate that the clay soil used is classified as organic clay with high plasticity based on the USCS classification, with an unconfined compressive strength value of 0.2 kg/cm2. The addition of nickel slag with concentrations of 3%, 6%, 9%, and 12% results in respective increases in unconfined compressive strength by 46%, 50%, 68%, and 47%. These findings demonstrate that the optimum nickel slag content of 6% provides the maximum unconfined compressive strength. Therefore, it can be concluded that nickel slag, as a source of silica, has the potential to be used as an alternative material in soft soil improvement.

Mechanical properties of a high plasticity clay mixed with sand and low-plastic silt

It is of fundamental importance in geotechnical engineering practice to have a comprehensive understanding of how the mechanical properties of widespread alluvial soils are affected with varying concentration of sand, silt, and clay particles. Moreover, among the available methods of chemical and mechanical stabilization of high plasticity cohesive soils, mixing this soil with sand and/or non-plastic silt still brings a cost-effective and environment friendly solution. In this study, clay-sand and clay-silt mixtures were prepared by adding sand and silt to the clay samples in different proportions to explore geotechnical properties of sand-clay and silt–clay mixtures and develop empirical correlations for Atterberg’s limits, compaction properties, unconfined compression strength, and consolidation characteristics for these soil mixtures. It was observed that for additive contents of up to 50%, the liquid limit and plasticity index of high plasticity clay sample decreased by 36% and 55% (with silt) and 47% and 58% (with sand), respectively. The reduction in undrained shear strength determined from unconfined compressive strength tests was about 37% with silt and 59% with sand contents. The compression index decreased by almost 13% with silt and 39% with sand. Likewise, it was also observed that the coefficient of consolidation increased with addition of silt and sand by 57% and 87%, respectively. As the increase in silt and sand content transformed the soil into a compact mass which ultimately should lead to a decreased total settlement as well as the rate of settlement of such soils. The statistical models proposed in this study have high coefficient of determination which depicts the reliability of these models in predicting the mechanical properties of sand-silt–clay mixtures.

Optimal density for effective chemical stabilization of deficient soils for road structures

Clays are deficient soils in pavement construction due to presence of secondary clay minerals which are usually stabilized to improve its engineering properties. Calcium carbide residue (CCR) and Zeolite wastes have both been identified as soil stabilization additives due to presence of calcium ion in the CCR and amorphous silica in zeolite. However, various researchers uses varied compaction energy level to mold specimen for relevant tests. This study is aimed at compacting CCR and zeolite treated clay at five different energy levels to determine the energy level that gives the highest strength and stability. For each compaction energy, the untreated and treated clay were prepared and some selected mixtures were sent for microstructural tests. Unconfined compressive strength (UCS) and California bearing ratio (CBR) specimen were cured tested at predetermined maximum dry density (MDD) and Optimum moisture content (OMC). The MDD increased with compaction energy while the OMC reduced in the same order. The XRD micrograph of specimen treated with CCR and zeolite revealed disappearance of delayed ettringite peaks from untreated clay with formation of microcline and anorthite. The SEM showed the formation of cementitious calcium silicate hydrate (C-S-H) filling the pores in the untreated clay to form a compact mass. The unconfined compressive strength (UCS) increased to 2300kN/m2 for the treated clay after 180 days curing. The CBR values increased from 3% for untreated clay to 260% for treated clay. The durability test showed result of between 72% and 84% for treated clay which satisfy the 70% minimum specified by standard. These UCS and CBR values satisfy the requirement for sub-base of highly trafficked roads. The UCS and CBR results for specimen cured for 180 and 60 days respectively revealed that the optimum compaction energy for effective CCR and zeolite stabilization occurred in Reduced Modified Proctor energy level.

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.

An Experimental Design Methodology to Evaluate the Key Parameters on Dispersion of Carbon Nanotubes Applied in Soil Stabilization

The incorporation of carbon nanotubes (CNTs) in the process of chemical stabilization of soft soil is only possible when they are dispersed adequately in the medium. The maximum compressive strength (qu max) and the secant undrained Young’s modulus (Eu 50) are usually used to characterize the behavior of soil stabilized with Portland cement. In the present study, soft soil was additivated with a CNT dispersion prepared in a surfactant solution. This information was then used to produce a model based on an experimental design strategy, which allowed us to relate qu max and Eu 50 with the CNT concentration and the surfactant hydrodynamic diameter and concentration. The Partial Least Squares (PLS) regression method was selected to perform the regression, given the significant collinearity among the input variables. The results obtained lead us to conclude that the CNT concentration is the most important factor and has a positive impact on the responses (qu max and Eu 50). The surfactant concentration and hydrodynamic diameter have a negative impact on the responses, but, curiously, when combined, the impact becomes positive. It means that these variables depend on each other. The results obtained show that it is possible to produce a statistical model for these parameters with good correlation coefficient (R2).

Chemical Stabilization of Clayey Soil Using Blend of Calcium Carbide Residue and Ground Granulated Blast Furnace Slag

Chemical Stabilization of Clayey Soil Using Blend of Calcium Carbide Residue and Ground Granulated Blast Furnace Slag

Geotechnical performance of tropical laterite soil using palm oil fuel ash and activator magnesium oxide stabilizer

Agricultural by-products waste, such as palm oil fuel ash (POFA) and magnesium oxide (MgO) activator, were utilized to achieve the chemical stabilization of laterite soil. This approach is environmental friendly as it aims at eliminating the potential hazards related to improper waste disposal methods and decreasing greenhouse gas emission generated by cement production to enhance the compressive strength of the soil. In this work, different percentages of additives ranging between (10% and 40%) with the addition of MgO between (2.5%and10%) were incorporated into the examined soil and cured at room temperature. Unconfined compressive strength (UCS) test, flexural strength (FS) test, scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis were conducted to examine the stabilized soil samples. The results showed that UCS values of LS-POFA-MgO sample increased up to 3.56 and 5.05 MPa after 7 and 28 curing days when the POFA-MgO was used at a ratio of 30:10, respectively. An increase of approximately 17 times greater than the untreated soil was also found. The FS LS-POFA-MgO showed a significant increase, exhibiting an enhanced peak behavior, thereby reducing deflection with brittleness. The findings were also substantiated by the pozzolanic activity enhancement of the former composition, as validated by the EDX patterns and SEM analyses. Therefore, the use of POFA based MgO activator is effective in addressing some soil issues and selecting the best soil mixtures. Furthermore, the soil's compressive strength improved significantly, making it suitable for utilisation as a material for the pavement base.

Stabilization of Gypsum Clay Soil by Adding Lime

Often, the temperature and water variation exist in semi-arid areas of a clayey soil leads to vertical and horizontal settlements, cracks in the soil and in general disorder to the building installed on this soil. The objective of this work is to stabilize the local gypsum clay soil, which poses problems at the level of self-construction built on it. Chemical soil stabilization can improve soil properties. In fact, adding natural lime to these clays can provide an ideal solution for stabilizing them through interesting modifications to their geotechnical properties throw the experimental tests on both unstabilized and stabilized soil samples by adding lime in quantities of 2, 4, and 6%, in percentages by the soil's weight, prepared at room temperature, The unconfined compressive strength (UCS) at different curing ages is measured, The results obtained provide a significant increase in compressive strength and modulus of Elasticity which allow better qualities and improve strength parameters throughout any phase of earthwork construction design that leads to strengthening subgrades, reducing the thickness, and, as a result, low construction costs. The results of the study show that (1) for the best utilization effect, the optimum percentage of lime is 6%; (2) the UCS is 3.23 times of the pure soil after curing of 28 days under the optimum percentage of lime; (3) the curing age has a significant effect on strength; (4) the main reason for the strength increase of the modified soil is that the crystal produced by the pozzolanic activity fills the pores of the soil. The ideal percentage is 6% lime treatment with a resistance of 2.3 MPa and 135.60 MPa the value of elasticity modulus at 28 days. Doi: 10.28991/CEJ-2022-08-11-010 Full Text: PDF

Bio-cementation by using microbially induced carbonate precipitation technique by using sporosarcina pasteurii with oxidizing agent supplements

In recent years, the natural biomineralization of bacterial metabolism to form calcium carbonate has drawn researchers and engineers' attention to exploring various applications for industrial purposes. Generally, microbially induced carbonate precipitation (MICP) is a biogeochemical process that can be applied to strengthen materials, including soil and sand structure, to overcome the chemical soil stabilization technique's limitations. In this study, Sporosarcina pasteurii was used to form CaCO3 by ureolytic MICP for soil-sand reinforcement in LAB-scale. As preliminary results, the increasing of CaCO3 crystals over curing time was an essential parameter for creating strong bonding between the soil-sand particles. Besides, the positive results in the water permeability test with the materials analysis as SEM, XRD demonstrated bacterial bio-cementation of sand specimens. Also, experimental results about oxidizing agent supplements show a positive effect on improving MICP capacity. Despite many challenges, bio-mineralization or bio-cementation is a promising technique for soil-sand stabilization in geotechnical engineering and building material applications, leading to sustainable development

Influence of Compaction Energy on Cement Stabilized Soil for Road Construction

Compactness is an important feature to ensure subgrade stability where temperature and water infiltration exist in semi-arid areas. Chemical soil stabilization can improve soil properties. This research studies the impact of compaction energy on stabilized subgrade soil and how to improve its geotechnical characteristics in the experimental tests on both unstabilized and stabilized soil samples by adding ordinary Portland cement and sulfate-resistant cement, in percentages by the soil's weight, in order of identification and classification, to the strength properties tests: compaction at multiple energies, CBR, and UCS. A test protocol was followed to assess the relationship between cement soil treatment, mechanical characteristics, and compaction parameters at different energy levels. Findings show that the higher UCS values were recorded with an increase in compaction energy. The MDD of cement stabilized soil increases as compaction energy increases, whereas the OMC decreases, the UCS improves, and the CBR increases. These improvements have a positive influence on the performance of soil used as a subgrade. The combination of cement stabilization and a high compaction level for subgrades using weak soil can improve strength parameters throughout any phase of earthwork construction design that leads to strengthening subgrades, reducing the thickness, and, as a result, low construction cost. Doi: 10.28991/CEJ-2022-08-03-012 Full Text: PDF

Partial Replacement of Conventional Material with Stabilized Soil in Flexible Pavement Design

Due to rapid urbanization and industrialization, the construction of roads increases rapidly for easy and fast transportation. Adequate land is not available everywhere to construct good roads; hence, roads are forcefully built on locally available soil such as loose soil or expansive soil. In this paper, an experimental investigation was carried out on low plastic soil (LPS) to enhance engineering properties by using chemical soil stabilization (fly ash-based geopolymer). The design of flexible pavement thickness was carried out for conventional and stabilized soil material using IITPAVE software as per IRC 37 guidelines. The results show the feasibility of fly ash-based geopolymer significant enhancement of strength were observed in terms of unconfined compressive strength (UCS) for various curing days (0 to 128 days), California bearing ratio (CBR), and Resilient modulus (MR). The microstructural analysis via Scanning Electronic Microscope (SEM) and X-Ray Diffraction Analysis (XRD) was also reveling the formation of geopolymeric gel which leads to the dense matrix to soil mass. The flexible pavement thickness significantly reduces with the application of stabilized low plastic soil.

Soil stabilization with ortho phosphoric acid and micro steel fiber

In this paper chemical stabilization of black soil is focused since the stabilization of soil mainly depends on chemical reactions between stabilizer and soil minerals compared to the physical process of soils properties. The phosphoric acid stabilization of soils is a relatively new method of chemical stabilization. In this paper chemical stabilization process using California Bearing Ration (CBR) tests are conducted on the black soil with the three percentages say 2%, 5% and 7% of soil weight by adding 85% ortho-phosphoric acid. One of the research and development materials namely micro steel fibers are adopted in increasing percentages of 0.4%, 2%, 4%, 6%, 8%, 10% and 12% to the best soil proportion after determined from previous step to further increase the CBR value. The purpose of this investigation is to determine the effect of 85% ortho phosphoric acid and micro steel fiber treatments on the stability of cohesive soils and determine the best proportion of admixture soil properties among various.

Live-Scale Testing of Granular Materials Stabilized with Alkali-Activated Waste Glass and Carbide Lime

The increasingly strong search for alternative materials to Portland cement has resulted in the development of alkali-activated cements (AAC) that are very effective at using industrial by-products as raw materials, which also contributes to the volume reduction in landfilled waste. Several studies targeting the development of AAC—based on wastes containing silicon and calcium—for chemical stabilization of soils have demonstrated their excellent performance in terms of durability and mechanical performance. However, most of these studies are confined to a laboratory characterization, ignoring the influence and viability of the in situ construction process and, also important, of the in situ curing conditions. The present work investigated the field application of an AAC based on carbide lime and glass wastes to stabilize fine sand acting as a superficial foundation. The assessment was supported on the unconfined compressive strength (UCS) and initial shear modulus (G0) of the developed material, and the field results were compared with those prepared in the laboratory, up to 120 days curing. In situ tests were also developed on the field layers (with diameters of 450 and 900 mm and thickness of 300 mm) after different curing times. To establish a reference, the mentioned precursors were either activated with a sodium hydroxide solution or hydrated with water (given the reactivity of the lime). The results showed that the AAC-based mixtures developed greater strength and stiffness at a faster rate than the water-based mixtures. Specimens cured under controlled laboratory conditions showed better results than the samples collected in the field. The inclusion of the stabilized layers clearly increased the load-bearing capacity of the natural soil, while the different diameters produced different failure mechanisms, similar to those found in Portland cement stabilization.

Distinct Responses of Rare and Abundant Microbial Taxa to In Situ Chemical Stabilization of Cadmium-Contaminated Soil.

ABSTRACTSoil microorganisms, which intricately link to ecosystem functions, are pivotal for the ecological restoration of heavy metal-contaminated soil. Despite the importance of rare and abundant microbial taxa in maintaining soil ecological function, the taxonomic and functional changes in rare and abundant communities during in situ chemical stabilization of cadmium (Cd)-contaminated soil and their contributions to the restoration of ecosystem functions remain elusive. Here, a 3-year field experiment was conducted to assess the effects of five soil amendments (CaCO3 as well as biochar and rice straw, individually or in combination with CaCO3) on rare and abundant microbial communities. The rare bacterial community exhibited a narrower niche breadth to soil pH and Cd speciation than the abundant community and was more sensitive to environmental changes altered by different soil amendments. However, soil amendments had comparable impacts on rare and abundant fungal communities. The assemblies of rare and abundant bacterial communities were dominated by variable selection and stochastic processes (dispersal limitation and undominated processes), respectively, while assemblies of both rare and abundant fungal communities were governed by dispersal limitation. Changes in soil pH, Cd speciation, and soil organic matter (SOM) by soil amendments may play essential roles in community assembly of rare bacterial taxa. Furthermore, the restored ecosystem multifunctionality by different amendments was closely related to the recovery of specific keystone species, especially rare bacterial taxa (Gemmatimonadaceae and Haliangiaceae) and rare fungal taxa (Ascomycota). Together, our results highlight the distinct responses of rare and abundant microbial taxa to soil amendments and their linkage with ecosystem multifunctionality.IMPORTANCE Understanding the ecological roles of rare and abundant species in the restoration of soil ecosystem functions is crucial to remediation of heavy metal-polluted soil. Our study assessed the efficiencies of five commonly used soil amendments on recovery of ecosystem multifunctionality and emphasized the relative contributions of rare and abundant microbial communities to ecosystem multifunctionality. We found great discrepancies in community composition, assembly, niche breadth, and environmental responses between rare and abundant communities during in situ chemical stabilization of Cd-contaminated soil. Application of different soil amendments triggered recovery of specific key microbial species, which were highly related to ecosystem multifunctionality. Together, our results highlighted the importance of rare bacterial as well as rare and abundant fungal communities underpinning restoration of soil ecosystem multifunctionality during the Cd stabilization process.

Key-Parameters in Chemical Stabilization of Soils with Multiwall Carbon Nanotubes

Chemical stabilization is one of the most successful techniques that has been applied to improve the geomechanical behavior of soil. Several additives have been studied to be a sustainable alternative to traditional additives (Portland cement and lime) normally associated with high cost and carbon footprint. Nanomaterials are one of the most recent additives proposed. This work is focused on one type of nanomaterial, multiwall carbon nanotubes (MWCNTs) with unique characteristics, applied to chemical stabilization of soils and aiming to identify the key-parameters affecting the stabilization improvement. It was found that a surfactant should be added in order to oppose the natural tendency of MWCNTs to aggregate with the consequent loss of benefits. The surfactant choice is not so dependent on the charge of the surfactant but rather on the balance between the concentration and the hydrodynamic diameter/molecular weight due to their impact on the geomechanical compression behavior. As time evolves from 7 to 28 days, there is a decrease in the geomechanical benefits associated with the presence of MWCNTs explained by the development of the cementitious matrix. MWCNTs applied in a proper concentration and enriched with a specific surfactant type may be a short-time valid alternative to the partial replacement of traditional additives.

STABILIZATION OF SUBGRADE SOIL USING CALCIUM LIGNOSULFONATE AND GRANITE DUST- A REVIEW

India is a geographically diverse country with varied soil types in different places. As a result, stabilising techniques are employed to enhance those regions with low bearing capacity. Soil strength is improved using both mechanical and chemical stabilising techniques. In the mechanical approach, mechanical energy is employed (rollers, plate compactors, tempers, etc., depending on the choice or type of the soil) to enhance soil characteristics by compaction. Chemical Soil Stabilization is a chemical approach that involves blending and combining chemical additions to improve the soil’s engineering qualities. Chemical substances such as calcium lignosulfonate, granite dust, cement, and fly ash were added in. Although calcium lignosulfonate may stabilise a wide variety of soil types, it works best in soft soils and clay soils with moderate to medium flexibility. Granite dust is primarily used in clay soils with a lot of flexibility. KEY WORDS: Calcium lignosulfonate, Granite dust, soil, stabilization, subgrade

A COMPARATIVE STUDY OF SOIL STABILIZATION USING FLY ASH AND RICE HUSK ASH

Approximately 21.4% of the total geographical area of the country covered with Expansive soils. Chemical stabilization of soil using cement, lime etc, is costly. Stabilization of soil using solid wastes like Rice husk Ash and Fly ash which reduces the cost of chemical stabilization a review is made on Rice husk ash and Fly ash.RHA has rich amount of silica and FA believed to be one of the best pozzolans which may be used as chemical stabilizers for soil stabilization. The rice husk ash and fly ash is mixed in various proportions with soil like 5%, 10%, 15% and 20%. Various tests were also conducted on these mixes in order to find optimum proportions.