Properties Of Subgrade Soils Research Articles

Experimental study on deformation characteristics of seasonal subgrade soil under dynamic load.

In Northwest China, the highway infrastructure often faces challenges due to the widespread presence of subgrade soil. This soil undergoes significant changes in performance under cyclic loading and freeze-thaw cycles. To effectively design and construct highways in these regions, it is crucial to understand the impact of various factors on the deformation characteristics and mechanical properties of subgrade soil. This study aims to investigate the influence of freeze-thaw cycles, water content, confining pressure, and loading rate on the deformation behavior and mechanical properties of subgrade soil under cyclic loading conditions. Experimental tests were conducted to analyze the deformation characteristics and mechanical properties of the subgrade soil. The test results revealed the following: 1) Dynamic loading leads to a noticeable decrease in the strength of subgrade soil, resulting in a softening effect on the stress-strain curve. The cumulative strain of the soil is positively correlated with the number of freeze-thaw cycles and water content, while negatively correlated with confining pressure. The final cumulative strain remains below 1%. 2) The failure stress of subgrade soil decreases exponentially with an increase in freeze-thaw cycles, dropping from 224.52 kPa to 196.76 kPa. 3) An increase in water content linearly decreases the failure stress of subgrade soil, ranging from 377.1 kPa to 151.5 kPa. 4) Confining pressure exhibits a linearly increasing relationship with the failure stress of subgrade soil, ranging from 151.6 kPa to 274.5 kPa. 5) The failure stress of subgrade soil demonstrates a linear increase with the loading rate, ranging from 200.46 kPa to 210.62 kPa. These findings provide valuable insights for the design and construction of highways in seasonal frozen areas. They also offer guidance for preventing and mitigating subgrade freeze-thaw issues in the future.

Effect of Tannery Sludge Ash Additions on the Properties of Subgrade Soil Stabilized by Cement

Effect of Tannery Sludge Ash Additions on the Properties of Subgrade Soil Stabilized by Cement

Improvement of soft clay soil with a combination of pre-gelatinized corn starch and nanoparticle agro waste: A multi-objective grey wolf optimizer approach

The present study aimed to assess the potential of a bio-inspired algorithm, multi-objective grey wolf optimization algorithm (MOGWO), to optimize the strength properties (California bearing ratio (CBR) and unconfined compressive strength (UCS)) of an expansive subgrade soil. This optimization process involves the use of two additives, namely a bio-polymer, pregelatinized corn starch (PGCS), and a nanoparticle agro waste, rice husk ash (RHA), blended with the soil in different mix ratios determined by a 32 factorial experimental design. The CBR samples were cured for 7 days, while the UCS samples were cured for 1, 7, and 28 days. To optimize the expansive subgrade soil strength, regression models were developed using PGCS and RHA as predictors for CBR and UCS, serving as fitness functions in the slightly modified MOGWO optimization technique. Next, the optimization analysis produced non-dominated solutions. The results obtained from the laboratory experiments and optimization analysis revealed that there was significant improvement in the UCS and CBR of the soil. These improvements can be attributed to the pozzolanic reaction between the soil-RHA matrix, the formation of intercalated and exfoliated nanocomposites, and the hydrophilic interaction of PGCS. By applying the slightly modified MOGWO technique, the study achieved optimal enhancements in UCS (710.3 kN/m2) and CBR (24.2%) when the expansive subgrade soil was mixed with 0.2637% PGCS and 12.2413% RHA. The results demonstrate the potential of the MOGWO technique in improving the properties of expansive subgrade soil.

Analysis and Design of Flexible Pavement and Cost Comparison with Cement-Treated Base and Subbase Material

Road transport is important in economic, social; and a country’s overall development. Various commercial vehicle classes have utilized roads with different axle configurations and loads. Due to the cumulative effect of wheel loads and the aging of bitumen binder flexible pavement starts deteriorating. The bitumen pavement failure is mainly due to fatigue cracking as well as rutting deformation. Thus, proper load analysis for the intended period of pavement planned life needs to be analyzed and the pavement designed accordingly. The development of software such as IITPAVE enables the calculation of stress and strain values at required points across various pavement layers. The project's goal is to gather traffic data as well as soil CBR values from the field to design a flexible pavement following IRC: 37-2018 guidelines. The pavement would be analyzed using IITPAVE Software to obtain the actual strains at required critical points. Pavement design is influenced by factors such as properties of subgrade soil, wheel load, climatic conditions, and pavement materials. Pavements are built according to IRC guidelines and MORTH specifications. Excessive strain along with the deformation at the critical locations in pavement are the primary causes of bitumen pavement failure. This research aims to design a flexible pavement and compare the cost of traditional pavement layer composition with cement-treated base as well as sub-base materials. Keywords: Flexible Pavement, Cement treated base (CTB) and Subbase (CTSB), Cost Comparison.

Effectiveness of lime kiln dust on swelling of subgrade expansive soil

BackgroundThe structure of flexible or rigid pavement built on expansive subgrade soil that has a volumetric change is vulnerable to many problems that might cause failure. Pavement and construction became more durable and economical by enhancing the quality of subgrade expansive soil. Solid waste recycling has become very popular recently as a means of attaining sustainable waste management, so using lime kiln dust (LKD), which is a by-product of quick lime production, to treat expansive soil in pavement subgrades. This research describes the effect of LKD on the chemical composition, strength, and swelling of high and low-plastic clay that were extracted from two sites. The minimum LKD required for treating expansive soils was determined by using the Eades and Grim pH test. From tests, it was found that the addition of LKD increased the shrinkage limit by a range (250–500)% and decreased the plasticity and swelling potential by between (50 and 100)% of expansive subgrade soils. The strength according to CBR, increased approximately by 150% for CL soil and 800% for CH soil.ResultsThe optimal percentage of LKD for CH soil is 6%, and for CL soil, it is 2%. The plastic limit increased by 50% for CH soil at 6% LKD. On the other hand, CL soil became non-plastic at 4% LKD. With an increase in the percentage of LKD, it led an the increase in the shrinkage limit by 500% in CH soil and 250% in CL soil. The free swell decreased by 50% in CH soil and 100% in CL soil. The swelling pressure decreased by 50% for two expansive soils. CBR increased by 800% in CH soil and by 150% in CL soil.ConclusionThis work found that the addition of LKD improves the physical, chemical, and mechanical properties of expansive subgrade soil.

Structural, soil-water, and dynamic characteristics of clay with different moisture and temperature histories

Variations in the hydro-mechanical properties of pavement subgrade soils are complex under long-term, repeated, and interlaced moisture and temperature (M-T) effects, such as wetting-drying (WD) and freeze-thaw (FT) processes. This study compares the soil structure, soil-water characteristic curves, and accumulated plastic strain (ɛ p) of compacted Heilongjiang clay with three different M-T histories. Experimental results demonstrated that (i) after M-T actions, structural pores develop while textural pores shrink, leading to a reduction in the water retention capacity and an increase in the desaturation rate. Following the stabilization of the M-T effects, the soil structure and soil-water characteristics of specimens with different M-T histories become similar; (ii) at high moisture content (w), ɛ p is more sensitive to moisture changes (including w and suction, s). Following the FT cycles, ε p and ε pa (the difference between the ε p at 5000th and 3000th cyclic loading) become more sensitive to moisture changes; (iii) after M-T effects, the ε pa-w relationship is nonlinear while the ε pa-logs relationship is linear. Different M-T histories generated differences in only the ε p at the beginning of the FT processes while such differences disappear after M-T effects have stabilized. The experimental data presented in this paper could prove valuable in understanding the behaviors of pavement soils under complex environmental conditions.

Experimental Study on Subgrade Soil Properties using Sea Water as Partial Replacement to Fresh Water in Coastal Areas

At present , the fresh water availability is very important factor specially in coastal areas the ground water table providing with sea water . If we utilize the waste water nothing but sea water is used as parital replacement to the fresh water for the construction of subgrade soil for flexible pavements ,we will reduce the utilization of fresh water to the construction works as well as economical for transportation of fresh water to construction site. Sub grade is a component which can taken all compression loads from sub base, base and surface courses and transfer to it to below the ground surface. This paper deals with the sub-grade properties using sea water as partial replacement to fresh water in coastal areas. In order to determine the properties of soil by taking various percentages I.e, 10%,20%,30%,40% and 50%of salt water as partially replaced to normal water. In this study, Proctor’s compaction tests, core cutter test,Atterberg limits and CBR soaked and un-soaked tests are conducted on locally available soil with sea water to normal water. For this study it is identified that the engineering properties of the soil like void ratio,posrosity,degree of saturation does not loose their characterstics in all conditions. The soil with at optimum value is 40% of sea water has CBR soaked value is obtained 6.83% and un-soaked value is obtained 7.0% is just increased when compared with conventionally soil. Key Words: CBR-Soaked, Un-soaked,sea water, locally available water, compaction test, atter berg limits

Experimental Study on Mechanical Properties of Highway Subgrade in Cold Regions under Different Conditions

In order to study the changes in the mechanical properties of road subgrade in cold areas after the freezing and thawing of highways in cold areas, indoor mechanical tests were carried out to investigate the effects of the number of freeze–thaw cycles, freezing temperature, water content, and circumferential pressure on the mechanical properties of road subgrade soil in cold areas after thawing. The mechanical properties of road subgrade soil in cold areas after thawing were measured under different conditions. The test results show that, within the study range: (1) After 7 freeze–thaw cycles, the destructive stress of the subgrade soil decreased from 321.7 kPa to 289.9 kPa, a decrease of 9.9%, and the elastic modulus decayed by 19.9%. (2) When the freezing temperature was reduced from −5 °C to −15 °C, the destructive stress of the subgrade soil decreased from 303.9 kPa to 290.1 kPa, a decrease of 13.8 kPa, approximately 4.5%, and the decrease in modulus of elasticity was about 1.6%. (3) The water content increased from 6% to 12%, and the destructive stress decreased from 405.43 kPa to 288.4 kPa, a decrease of 29.1%, and the modulus of elasticity decreased approximately linearly, with an attenuation of 50.4%. (4) The peripheral pressure increased from 50 kPa to 150 kPa, and the destructive stress increased from 194.7 kPa to 367.7 kPa, a growth of 88.8%, and its modulus of elasticity increased with the increase in peripheral pressure, an increase of 154.1%. The results of this research can provide a reference for highway and engineering construction in the western silt–soil distribution area.

Effect of illite on the mechanical properties of subgrade soil under varying surcharge loads

Due to its non-expanding properties, presence of Illite mineral in subgrade soil is investigated particularly on California bearing ratio (CBR), resilient modulus (MR) and swell potential. Multiple samples of stiff and weak subgrade soils with varying illite percentages were tested under six different surcharge loads ranging from 2.27 to 13.8 kg. Mineralogical analysis is performed using X-ray diffractometer and MR of soil is assessed using Ultrasonic pulse velocity (UPV) technique. Results showed a positive correlation between Illite percentage and both CBR and MR value. The soil with higher Illite content tends to exhibit higher CBR and MR values while those with higher montmorillonite content show lower values even with more Illite content. The CBR and MR values increases from 8.4% to 19 % and 139 MPa–315 MPa for stiff soil and 3.8%–11.7 % and 23 MPa–83 MPa for weak soil, respectively when the surcharge load was increase from to 2.27–13.8 kg. Additionally, a decrease in swell potential was observed from 1.64% to 1.09 % for stiff soil and 1.39%–0.84 % for weak soil with an increase in Illite percentage. The study also developed an improved relationship for predicting resilient modulus based on CBR value, showing a strong correlation with equations developed by many researchers in the past.

Strength improvement of clay subgrade soil stabilised with recycled concrete aggregate and granulated blast furnace slag

In this research, a combined method of chemical and physical stabilisation has been used to investigate the effect of using recycled concrete aggregate (RCA) and granulated blast furnace slag (GBS) in improving the strength properties of subgrade soil. A comprehensive series of compaction, uniaxial compressive strength (UCS) and California bearing ratio tests were performed on different mixtures. The results show that UCS values increased for clay subgrade with up to 20% RCA content and decreased after that. The subgrade soil with 20% RCA was treated with GBS to obtain the target uniaxial strength for stabilised subgrade soils. Also, the results obtained from investigating the effect of freeze–thaw cycle on the UCS of the optimum combination with different GBS content show that the F-T cycle reduces the value of the UCS from 32% to 53% after 12 F-T cycles.

Dynamic deformation and meso-structure of coarse-grained saline soil under cyclic loading with freeze-thaw cycles

The cumulative deformation properties of subgrade soil under cyclic traffic loads are critical for optimizing pavement structure design and ensuring long-term highway structural performance. This study aims to investigate the coupling effect of freeze-thaw cycles and cyclic loads on the cumulative deformation behaviors and meso-structure of coarse-grained saline soil (CGSS) subgrade filling in high-cold areas. Dynamic triaxial tests and computed tomography (CT) scanning were conducted to analyze the CGSS under different working conditions. The research focused on the dynamic deformation development and damage evolution under varying freeze-thaw cycles and load amplitudes. The research results show that the cumulative deformation behavior of CGSS under cyclic loading is relatively sensitive to the freeze-thaw process. The cumulative dynamic strain increases as the freeze-thaw cycles, with a critical freeze-thaw cycle number of five. The stable cumulative dynamic strain curve exhibits clear three-stage characteristics when plotted in semi-log coordination, with critical loading cycles at 20 and 1,000. After 10–100 loading cycles, the cumulative strain curve quickly shows failure. The CGSS’s low density and pore regions greatly increase after a freeze-thaw cycle. The rise in dynamic stress amplitude notably affects the bonding between soil particles and crystalline salts. The coupling effect of the freeze-thaw cycle and dynamic activity exacerbates the deterioration of soil structure, resulting in variations in CT values within the scanning layer in the final state.

Geopolymerisation and micro-pore assessment of soft soil used as flexible pavement material in road construction

In this study, inexpensive dual precursors namely rice husk ash (RHA) and quarry dust (QD) were mixed with an alkali solution (NaOH solution) in different mix proportions. Next, the effect of the dual precursors-alkali solutions (geopolymers) on the strength parameters of the different soil-geopolymer mixes subjected to various curing days were assessed. The result obtained from the assessment showed that the dual precursors-alkali solutions improved the strength properties of all the different soil-geopolymer mixes. The optimum soil-geopolymer mix proportion that resulted in the best improvement of the expansive subgrade soil properties was observed at a combination of 15%RHA+15%QD+3M NaOH. Furthermore, micro-pore analyses (porosity and pore size distribution), which were implemented with scanning electron micrographs and an image segmentation technique, local adaptive thresholding algorithm, showed progressive reduction in the porosity of the natural expansive subgrade soil and that of the optimal soil-geopolymer mix proportion cured for 7 and 28 days.

Research on intelligent compaction stiffness index and its application based on three-degree-of-freedom elastic–plastic dynamical model

CMV (Compaction Meter Value) and stiffness coefficient ks are the two most commonly used indexes in the intelligent compaction technology for subgrade soil. However, the applicability of CMV is affected by the operation mode and the working parameters of the vibrating roller. The calculation model of stiffness coefficient ks does not consider the plastic characteristics of the soil and the data usage rate of its calculation method is low. As a result, the current ICMVs (intelligent compaction measurement values) are only applicable to the compaction quality characterization in the later stage of compaction, and the accuracy and applicability of the compaction quality characterization in the whole process of construction are low, which limits the application of intelligent compaction technology. In view of the above problems, this paper aims to establish a comprehensive stiffness coefficient index which is not affected by the operation mode of the roller, comprehensively reflects the elastic–plastic mechanical properties and has strong resistance to accidental factors, in order to provide an accurate basis for the characterization of subgrade soil compaction quality. Firstly, a numerical simulation model of subgrade soil vibrating compaction with real-time change of soil Mohr-Coulomb model parameters with triaxial strain response is established, which provides accurate data support for ICMV calculation. Secondly, the calculation model and application method of CMV and ks are analyzed. Aiming at the shortcomings of the two indexes, the comprehensive stiffness coefficient kcs reflecting the elastic–plastic characteristics of soil and its complete calculation method are established. Finally, based on the simulation data, the accuracy of kcs is verified, and the variation law of the kcs calculation model parameters and the evolution mechanism of soil elastic–plastic properties are clarified. Based on the field tests data, the accuracy of kcs is verified. The results show that the deciding coefficients between kcs and compaction degree obtained by numerical simulation and field test are R2 = 0.83 and R2 = 0.72, respectively, which are higher than that between ks and compaction degree (R2 = 0.72, R2 = 0.52) and that between CMV and compaction degree (R2 = 0.04, R2 = 0.23). The accuracy of kcs to characterize compaction quality is higher, and it can maintain high stability during field application. During the compaction process, the elastic–plastic mechanical properties of subgrade soil evolve continuously, and each parameter of kcs calculation model increases with the rolling pass.

Sustainable Lignin to Enhance Engineering Properties of Unsaturated Expansive Subgrade Soils

New ways to apply sustainable materials, such as biomass components, are essential for reducing dependence on fossil fuels. This work investigated the engineering properties of unsaturated expansive subgrade soils stabilized by bio-based energy coproducts containing lignin. Lignin is a waste by-product of the paper and pulp industry that is frequently burned. Highway subgrade could consume lignin as an environmentally benign, low-cost, and energy-efficient chemical substance for soil stabilization. Swell and shrink behavior of expansive subgrade soils complicates highway construction and causes damage to existing highways. However, research on the hydromechanical properties and volume change behavior of lignin-stabilized expansive soil is limited, and better insight is required into its unsaturated behavior for safe and economical pavement design practices. In this research, a series of geotechnical laboratory tests were conducted to characterize expansive subgrade soils treated with lignin by determining the Atterberg limits, compaction and consolidation behaviors, swelling characteristics, and water retention properties. The mechanisms influencing the changes in engineering properties of lignin-treated expansive soils were further investigated using soil pH, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy analysis. The study shows that the optimal lignin content contributed to an acceptable degree of soil stabilization. The lignin-based cementing material effectively bonds soil particles together and fills pores, thereby preventing water infiltration into the soil and reducing the swell–shrink potential of stabilized soils.

Investigating the effects of stabilization carried out using fly ash and polypropylene fiber on the properties of highway clay soils

Improving highway subgrades is the most crucial step that increases the performance and longtime durability of pavements. Using fly ash to improve the properties of subgrades and synthetic fibers as additives to increase their strength in recent years is an effective method. It is essential to determine how fly ashes affect the strength properties of subgrade soils in the long term with a time-dependent curing effect and how synthetic fibers affect the strength properties of subgrade soils, especially in the short term before curing. Furthermore, another vital issue is determining the extent to which freeze–thaw cycles that occur during winter months due to regional climatic conditions reduce the strength of the subgrade soils. For this purpose, a regional high-plasticity soil representing the problematic subgrade was reinforced with fly ash at different percentages (10%, 20%, 30% and 40%), and a series of experiments were carried out to determine the plasticity, compressibility and strength properties of these soil mixtures. Besides the clayey soil and fly ash, the microstructures of these mixtures were also examined by XRF, XRD spectrometry, FT-IR spectroscopy and SEM analyses and the relationships between mechanical behavior and microstructure were tried to be explained. Furthermore, the impact of polypropylene fibers added to the soil at 0.5% of the dry mass and freeze–thaw cycles on the strength of the subgrade soils was determined. The results showed that the effective fly ash mixture ratio for stabilization with fly ash was 10%, and when the 28-day unconfined compressive strengths of the fly ash mixture and the natural soil were compared, the fly ash mixture increased the strength by 85.8%. Furthermore, the fiber additives were determined to increase the shear strength at ratios ranging from 3.0% to 21.0% and that approximately 80% strength loss occurred in the natural soil due to freeze–thaw cycles, but fly ash and synthetic fiber additives can increase the strength by compensating for the strength loss caused by freeze–thaw cycles.

Strength Improvement of Black Cotton Soil Using Plastic Bottles and Crushed Glass Wastes

The aim of this study was to improve the strength of black cotton soil for its suitability for road subgrade construction using wastes from plastic bottles and glass waste powders. Currently, nondecomposable wastes from plastic and glasses have become threats to the human health and the environment. This study used the wastes to replace cement, since the cost of cement raised due to energy and raw material to use as stabilizer in weak soil. The glass powder (WGP) and the plastic chips were mixed with the soil sample with a percentage by dry weight of 6%, 12%, 18%, and 24% of WGP and 2%, 4%, 6%, and 8% of plastic chips, respectively. The glass waste can be prepared similar to the soil as the requirement of test standards and plastic wastes was used as reinforcement for the soil-glass-mix; hence, its purpose was geomechanical. Laboratory tests for soil-mix physical properties and strength parameters were conducted. Soil laboratory test results proved that the natural soils were classified to A-7-5 as per the AASHTO Soil Classification System and CH as per the Unified Soil Classification System (USCS). The Unconfined Compressive Strength (UCS) improved from 91.92 kPa to 688.83 kPa, and the California Bearing Ratio (CBR) improved from 2.64 to 17.5. The improvement of subgrade soil properties was increased with increased ratios of powder glass and plastic strips. The result indicated that the two stabilizers were very effective in improving strength parameters and index parameters.

Curing Mechanisms of Polymeric Nano-Copolymer Subgrade.

The mechanical properties of the subgrade have a significant impact on the service life and pavement performance of the superstructure of pavement. By adding admixtures and via other means to strengthen the adhesion between soil particles, the strength and stiffness of the soil can be improved to ensure the long-term stability of pavement structures. In this study, a mixture of polymer particles and nanomaterials was used as a curing agent to examine the curing mechanism and mechanical properties of subgrade soil. Using microscopic experiments, the strengthening mechanism of solidified soil was analyzed with scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Fourier infrared spectroscopy (FTIR), and X-ray diffraction (XDR). The results showed that with the addition of the curing agent, small cementing substances on the surface of soil minerals filled the pores between minerals. At the same time, with an increase in the curing age, the colloidal particles in the soil increased, and some of them formed large aggregate structures that gradually covered the surface of the soil particles and minerals. By enhancing the cohesiveness and integrity between different particles, the overall structure of the soil became denser. Through pH tests, it was found that the age had a certain effect on the pH of solidified soil, but the effect was not obvious. Through the comparative analysis of elements in plain soil and solidified soil, it was found that no new chemical elements were produced in the solidified soil, indicating that the curing agent does not have negative impacts on the environment.

Subgrade improvement with mixed lime and cement as additives

The study deals with the utilization of mixed lime and cement for enhancing subgrade soil properties. Most of the research has been carried out utilizing the lime and cement individually. Less investigation has been done on mixing lime and cement and then adding in the soil to gauge its effect on the properties. The research work aims at investigating the effect of mixing the additives instead of using them individually. A series of tests were carried out, including Atterberg’s limits, modified Proctor and California Bearing Ratio in accordance with BS EN 1377-(2–4-9):1990 standards. The soil used for the research work was taken from the construction site of Paisley Museum in Paisley-Scotland. The mixture combinations adopted for testing were: Control/Untreated Sample, Lime 3% and Cement 1.125%, Lime 6% and Cement 2.25%, Lime 9% and Cement 3.375% replacement. The results showed interesting features, as the lime and cement utilized in combination showed a significant improvement in the values of the CBR (%) in comparison to previous research, where the lime or cement were used separately in the soil. With the increase of the percentage replacement of lime and cement combined, the CBR (%) with respect to the untreated samples of soil showed also significant increase. For a penetration of 2.5 mm, the increase in the soil CBR (%) was not significant in the beginning but after adding more stabilizer materials we have seen the values increasing up to 36%. On the other hand the increase was around 21 % for the CBR penetration of 5.0 mm.

The Effectiveness of Residual Soil, Orashi River Sand, and Sombrero River Sand as Stabilizing Agents for Subgrade Soil of Highway Pavement

The study investigated the effect of different stabilization materials, including residual soil and river sands, on the properties of subgrade soil for road and pavement structures. The results showed that the chemical composition of the subgrade soil was dominated by calcium, aluminum, and silicon, indicating a mineral clay soil. The use of stabilization materials led to a decrease in fines content and an increase in maximum dry density. The behavior of optimum moisture content was non-linear, and the liquid limit of the stabilized subgrade soil decreased significantly for all three materials, indicating a decrease in soil swelling ability. The study also revealed that the use of composite materials of cement and residual soil or river sand can improve the properties of subgrade soil and lead to an increase in unconfined compressive strength. The findings of this study can aid in the selection of appropriate stabilization materials and methods, and in the optimization of the use of these materials in road construction for improved strength and durability. Further research is needed to fully understand the characteristics of subgrade soil and determine the most effective methods for its stabilization and management. This study investigates the effects of residual soil and river sands on the mechanical properties of subgrade soil, with a focus on liquid limit, plastic limit, plasticity index, and unconfined compressive strength. The results suggest that residual soil, Orashi River sand, and Sombrero River sand are effective stabilizing agents for subgrade soil, with an increase in strength observed with increasing percentages of stabilizing material. However, there is an optimum content of stabilization material required to achieve maximum strength values, beyond which the strength decreases. The study also highlights the importance of considering the effect of soaking on the strength of subgrade soil and demonstrates the effectiveness of using composite .........

The Effectiveness of Cement and Lime as Stabilizers for Subgrade Soils with High Plasticity and Swelling Potential

This study investigated the effects of cement and lime on the mechanical properties of subgrade soils, which are challenging to stabilize due to high plasticity and swelling potential. The study found that both cement and lime are effective stabilizing agents that increase the OMC, with cement being more effective in reducing the OMC of black cotton soil. The engineering properties of stabilized Chokocho subgrade soil were also evaluated, and the use of cement and lime as stabilizers was found to be effective in improving soil characteristics for subgrade applications. This was indicated by increased maximum dry density values, reduced plasticity index values, and increased California bearing ratio and unconfined compressive strength values. The chemical composition test demonstrated that calcium plays a significant role in soil stabilization, while aluminum can potentially affect soil stability negatively. Other elements such as magnesium, iron, silicon, zinc, and nickel contribute positively to soil stability. The low amounts of lead, copper, manganese, potassium, sulfur, and titanium present in the soil indicate a minor contribution to soil stabilization, but their impact on soil properties and plant growth cannot be ignored. Overall, the study highlights the importance of considering specific soil types and conditions when undertaking soil stabilization projects. The findings provide valuable information for future research in this field, particularly in investigating the effectiveness of other stabilizers and their interactions with specific soil types. The use of cement and lime in soil stabilization is an effective method for enhancing the strength and durability of weak soils, as shown by the reduction in plastic limit values observed in the stabilized soil samples. The appropriate content of cement and lime to use in soil stabilization could inform standards and codes for soil stabilization.