Soil Improvement Techniques Research Articles

Polymer-assisted soybean crude urease carbonate precipitation technique for soil improvement

Polymer-assisted soybean crude urease carbonate precipitation technique for soil improvement

Bhargavaea beijingensis a promising tool for bio-cementation, soil improvement, and mercury removal

Microbially Induced Calcite Precipitation (MICP) has emerged as a promising technique for bio-cementation, soil improvement, and heavy metal remediation. This study explores the potential of Bhargavaea beijingensis, a urease-producing bacterium, for these applications. Six ureolytic bacteria were isolated from calcareous bricks mine soil and screened for urease and calcite production. B. beijingensis exhibited the highest urease activity and calcite precipitation. Urease activity, calcite precipitation, sand solidification, heavy metal removal efficiency, and compressive strength were evaluated. It showed significant heavy metal removal efficiency, particularly highest for HgCl2. Mortar blocks treated with B. beijingensis or its crude enzyme exhibited improved compressive strength, suggesting its potential for bio-cementation. Crack remediation tests demonstrated successful crack healing in mortar blocks using the bacterium or its enzyme. This study identifies B. beijingensis as a novel and promising MICP agent with potential applications in bio-cementation, soil improvement, and heavy metal remediation. Hence, B. beijingensis diversified abilities prove superior performance compared to commonly used strains like Bacillus subtilis and Shewanella putrefaciens in bio-cementation applications. Its high urease activity, calcite precipitation, and heavy metal removal abilities make it a valuable candidate for sustainable and eco-friendly solutions in various fields.

Undrained cyclic responses of sandy soils improved by soybean-induced calcium carbonate precipitation

ABSTRACT This study investigates the behaviour of sandy soils under cyclic conditions, emphasising the efficacy of soybean-induced calcium carbonate precipitation (SICP) treatment in mitigating liquefaction. Analysis of shear wave velocity and undrained cyclic responses was conducted, with a focus on understanding deformation response and development of excess pore pressure. Results revealed CaCO3 content as a definitive indicator for improvements in soil stiffness, with its distribution influenced by soil’s relative density and number of SICP injections. Enhanced cementation efficacy was observed in denser or deeper layers of sand column, attributed to prolonged SICP retention. A marked correlation between shear wave velocity and CaCO3 content highlighted SICP’s role in enhancing the liquefaction resistance of loose sandy soils. Dynamic triaxial testing showed the nuanced strain behaviours across varying relative densities and cyclic stress ratio (CSR) values, emphasising the strengthening influence of CaCO3 formations in the soil matrix. The empirical equation served as a testament to the potential of SICP in soil stabilisation endeavours. The intervention of SICP treatment presents a potent tool for bolstering soil stability, especially in regions susceptible to seismic activities. The insights garnered advocate for further research aimed at harnessing and optimising this soil improvement technique on a global scale.

Soil Water Characteristics Curves (SWCC) of Residual Soils Stabilized using Emerging and Novel Bioinspired Technique

The development of unsaturated soil mechanics stemmed from the inadequacies of classical soil mechanics in addressing the partial pore spaces found in real-world soil systems. However, assessing soil parameters under partial saturation is resource-intensive. To streamline this, the Soil-Water Characteristic Curve (SWCC) theory was introduced. Widely applied across geotechnical engineering, water resources, and agriculture, SWCC predicts parameters of unsaturated soil systems. In geotechnical engineering, SWCC is vital for designing systems near the Earth's surface, like slopes, clay liners and foundations. Furthermore, most of conventional soil improvement techniques pose a lot of environmental concerns. thus, emergence of green construction materials widely known as bio mediated and bioinspired soil improvement techniques like Enzymatic induced calcite precipitation (EICP). EICP, an emerging eco-friendly as it employs use of simply chemical compound that reduces carbon footprints, bioinspired technique as it mimics natural forming process, was applied to stabilize tropical soil for SWCC determination. SWCC parameters were derived by subjecting EICP-treated soils at varying concentration of cementation solutions (0 – 1.00 M) using pressure plate method. Results revealed that saturated water content θs, retention water content θr, and air entry value Ψa increased with higher cementation solution concentration. The values of θs, θr, and Ψa improved from of 0.663, 0.23405, and 3.4832 at 0 concentration of cementation solution to 0.701, 0.22864, and 7.7086, respectively upon treatment with 1.00 M cementation solution. Finally, it has been demonstrated EICP is capable of improving the SWCC parameters of residual soil, thus the EICP technique can be exploited in stabilization of residual for construction of compacted clay liner.

Physical property of MICP-treated calcareous sand under seawater conditions by CPTU

MICP (Microbially induced calcite precipitation), an environmentally friendly soil improvement technique, has great potential in ocean engineering due to its ability to promote the precipitation of calcium carbonate through microbial activity to enhance the engineering properties of geomaterials. In this study, piezocone penetration test (CPTU) is used to evaluate the effectiveness of MICP treatment in calcareous sand. The change of physical properties (relative density Dr and total unit weight γt) of MICP treated calcareous sand is investigated by conducting CPTU on the geomaterials prepared in a series of mini calibration chambers (25 cm × 50 cm). Results indicate that CPTU (tip stress, sleeve friction, and porewater pressure) measurements can be used to interpret the physical characteristics of calcareous sand treated with MICP under seawater conditions. Additionally, a relationship between CPTU measurements, physical parameters (relative density Dr and total unit weight γt) of MICP treated calcareous sand is proposed and calibrated. The findings of the research extend the implementation of in-situ testing techniques such as CPTU towards physical property evaluation of bio-treated geomaterials in ocean environment, and demonstrate the potential of scaling up MICP techniques for broader engineering application.

Use of rise husks to improve the efficiency of MICP-based soil improvement technique

Biogrouting has been identified as the best alternative approach for the conventional cement and chemical grouts. Among the various types of biogrouting techniques, microbial induced carbonate precipitation (MICP) has been recently recognized as a promising pathway for producing biogrout material, hence densifying the weak soils. In MICP, calcium carbonate (CaCO3) biocement is produced through biochemical reactions induced by the urease enzyme. The efficiency and productivity of MICP can be further improved by introducing various additives, including fibers, organic polymers, powders, waste materials, etc. In this research, rice husk was sustainably incorporated into the MICP process, and (i) the effect of the rice husk content, (ii) the concentration of the cementation solution and (iii) the treatment time on the unconfined compressive strength (UCS) of the sandy soil were investigated at the laboratory-scale. Cementation solutions with higher concentrations exhibited a higher UCS values than solutions with lower concentrations. Interestingly, the content of rice husk had a marked influence on the UCS, and the optimum rice husk content was 15%. Compared to that of the control sample (0% rice husk), a threefold greater UCS was obtained for 15% of the rice husk content sample. The outcomes further suggested that longer treatment with lower concentration of cementation solution was the best combination for achieving effective cementation within the sand matrix. Rice husk acted as the template for CaCO3 crystals to nucleate while promoting the efficient formation of CaCO3, indicating that the rice husk is an excellent additive to improve the efficiency of the MICP biocementation in a sustainable way.

Investigation of dynamic effect of rapid impact compaction

Dynamic compaction is a soil improvement technique which involves the repeated application of an impact load to a contact area of the soil surface induced by heavy weights. Experimental measurements were prepared for evaluation of the ground wave propagation induced by the rapid impact compaction. Influence of increase of subsoil stiffness during compaction and terrain configuration were investigated. When the shear strength of soil is exceeded during the penetration of the compaction footing, increase of peak particle velocities is slower but still clearly visible along the measurement line. The peak particle velocity is damped by the subsoil below 5 mm s−1 within 40–50 m from the source of excitation. Attenuation radius is affected by the terrain configuration, when terrain elevations cause the increase of acceleration amplitudes. Rigid bodies in the ground, such as foundation structures, could have similar influence. Dominant frequencies are in the interval from 20 to 40 Hz regardless the distance from the source of excitation or the density of the treated subsoil. Obtained results are preferably related to the given boundary conditions. However, wave propagation pattern and change of its characteristics during densification of the subsoil are applicable at another construction sites considering their particularities.

Miniaturized device to measure urease activity in the soil interstitial fluid using wenner method

This paper presents a microdevice developed to measure the electrical conductivity of a liquid or a saturated porous medium using Wenner method. It is developed in the context of biocementation as soil improvement technique, which is used in Civil Engineering applications to produce calcium carbonate through bacterial or enzymatic activity, replacing the use of other binder materials such as cement or resins, and therefore reducing carbon footprint. The microdevice was used to measure urease activity in the soil interstitial fluid, to investigate if bacterial activity could be affected by the presence of the particles and tortuosity from pore geometry. Such analysis is important to understand biocementation mechanism inside the soil and helps to improve the design of such treatment solutions. The device is basically a squared reservoir printed in polypropylene using a 3D printing machine, incorporating stainless steel electrodes in its base. The electrical resistivity was computed adopting Wenner method, by connecting 4 PCB electrodes to a signal generator and an oscilloscope for measuring the voltage when a AC current of 1 mA was applied. Both square and sinusoidal waves with 5 kHz frequency were selected among other frequencies. The measurements were adjusted during the calibration of the microdevice, done using standard salt solutions with known electrical conductivity measured using an electrical conductivity probe. For the bacterial activity measurements, the bacterial and urea solutions were added to a uniform-graded size quarzitic sand (average diameter 0.3 mm) placed inside the microdevice and covering completely the electrodes. Bacterial activity was not affected by the presence of the sand, which confirms that this treatment is effective for this type of soils.

Effect of sticky rice on the strength and permeability of bio-cemented sand

Microbially induced carbonate precipitation (MICP) is an eco-friendly soil improvement technique. However, this method still has some drawbacks, such as low conversion efficiency of CaCO3 crystallization, insufficient strength for certain applications, and requiring multiple treatments. Previous studies have reported that sticky rice can regulate CaCO3 crystals (i.e., chemical CaCO3) in the sticky rice-lime mortar, showing potential for improving the bio-cementation. Therefore, this study explored the possibility of using sticky rice to enhance the biocementation effect. Tests were carried out to assess the strength and permeability of bio-cemented sand with the inclusion of sticky rice. The results indicated that sticky rice may regulate the type and size of bio-CaCO3 crystals, and the use of an appropriate amount of sticky rice as additive could increase the strength of sand columns by regulating CaCO3 crystallization. Polyhedral calcites may be more favourable for the increasing strength than some vaterites with a hollow spherical structure. The combination of MICP and sticky rice can significantly decrease the coefficient of permeability to a value that was much lower than that by using sticky rice and MICP alone. Bio-CaCO3 immobilized the sticky rice on one end on sand particles, and the reticulated structure of sticky rice divided large pores into small pores, which may be the important cause of the decrease in permeability coefficient. Finally, this study proposed that the MICP with the sticky rice as an additive may enhance the MICP effect and prevent the surface erosion of coarse-grained sand slopes.

Experimental study on soil improvement by electrochemical injection of calcium chloride solutions with time interval

An improved electroosmotic method is proposed in this paper to enhance the non-uniform effect and efficiency of electroosmotic process. Such method is electroosmotic flow with injection of calcium chloride through the anode, followed by injection through the central tube (a tube at the midpoint between the anode and the cathode) with a suitable time interval between injections. Experimental results indicate that using this method can significantly improve the non-uniform reduction in water content throughout the soil, mitigate the formation of cracks in the anode section, and therefore considerably inhibit the increase in the electric resistance. After treatment, the drained water could be raised to 3.59 times more than that of pure electroosmotic flow, and 1.3 times that of simultaneous injection through both the anode and the central tube with considerably slight increase in power consumption. Moreover, the area of cementation was also expanded, approximately twice larger than that of pure electroosmotic flow and one and a half that of simultaneous injection. It is also worth noting that the proposed method performs better with the same power consumption. The results demonstrate that electroosmotic flow with a suitable time interval between injections could improve the efficiency of electroosmotic process and expand the treatment region in soils, hence can be a promising and economic technique for soil improvement in practical engineering.

Efficacy of soybean-derived crude extract in enzyme-induced carbonate precipitation as soil-improvement technique

Calcium carbonate precipitation using a urease enzyme, referred to herein as Enzyme-Induced Carbonate Precipitation (EICP) is a technique for soil improvement. In this technique, a mixed solution composed of reagents and the urease enzyme, which produces calcite, is utilized as the grouting material. Recently, alternative materials to the urease enzyme have been examined to resolve the cost issue of using the urease enzyme. In this study, several tests were conducted to compare commercial urease and soybean-derived crude urease. A comparison of their hydrolysis rates was done through urease activity tests. The microscopic structures and mineralogy of the precipitated materials, produced during various loading periods, were investigated through SEM and XRD analyses. Moreover, the reinforcing effect of the grouting solutions on the treated soil specimens was evaluated by measuring the unconfined compressive strength (UCS) of the treated samples. Interestingly, the precipitated CaCO3 was vaterite and calcite when using soybean urease, while it was mostly calcite when using the urease enzyme. Higher UCS values were obtained with the soybean urease samples because the precipitated CaCO3 seemed to be concentrated at the inter-grain contacts. It was concluded that soybean powder shows great efficacy as a replacement for commercially produced enzyme urease in soil-improvement techniques mediated by carbonate precipitation.

Micro- and nano-Illite to improve strength of untreated-soil as a nano soil-improvement (NSI) technique

Soil stabilization is a technique of improving the geotechnical properties of soils for various engineering applications. However, conventional stabilizers such as cement and lime have some limitations, such as high cost, environmental impact, and durability issues. Therefore, there is a need for alternative and innovative stabilizers that can overcome these challenges. This study introduces nano-Illite, a type of clay mineral, as a novel and effective soil stabilizer. Nano-Illite can form nano-cementation (NC) in soil, which is a process of enhancing the durability of various building materials. NC is also known as nano soil-improvement (NSI), a technique that has been developed in recent years. Four formulations of micro- and nano-Illite with concentrations of 0, 1, 2, and 3% were separately added to soil samples. The unconfined compressive strength (UCS) and the secant modulus at 50% of peak stress (E50) of the treated samples were measured and compared with the untreated samples. The results showed that 3% nano-Illite increased the UCS of soil by more than 2.2 times and the E50 by more than 1.5 times after 7 days of curing. Micro-Illite also improved the UCS and E50 of soil, but to a lesser extent. X-ray fluorescence (XRF), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses revealed the micro- and nano-structures of the soil specimens and the performance of Illite as a nano-additive. This research demonstrates the effectiveness of nano-Illite in soil improvement as a NSI technique, and its potential to replace or reduce the use of conventional stabilizers. This study also contributes to the understanding of the mechanisms and factors that influence the NC process in soil.

Effects of soil microbial ecology on ginsenoside accumulation in Panax ginseng across different cultivation years

The quality of ginseng is greatly influenced by ecological factors, especially soil factors. However, there are few reports on the association between the physicochemical properties of ginseng rhizosphere soil, enzyme activity, microbial bacterial community, and ginsenoside content accumulation in ginseng planted at different ages. In order to investigate the relationship between the soil microbial ecology of ginseng and the content of ginsenosides, this study compared the differences in the rhizosphere soil microecological environment and ginsenoside accumulation between ginseng planted for one, two, and three years, using soil without ginseng cultivation as a control. The results showed that monomer saponins Ro, Re, Rf, Rb1, and total ginsenoside content increased significantly (P < 0.05), while monomer saponins Rb2, Rd, Rh2, and Rg3 content decreased significantly in three-year-old ginseng, (P < 0.05). And soil pH, soil bulk weight and soil enzyme activity in ginseng rhizosphere soils altered the abundance and diversity of rhizosphere soil bacterial community. Redundancy analysis and Pearson correlation analysis revealed that soil pH, soil bulk density, soil urease, and protease were the primary factors influencing the bacterial community in the soil around roots of one, two, three years old ginseng. Co-occurrence network visualization analysis indicated that seven bacterial communities, Planctomycetota, Methylomirabilota, Verrucomicrobiota and Acidobacteriota at the phylum level, Vicinamibacterales_unclassified, Vicinamibacteraceae_unclassified and Candidatus_Udaeobacter at the genus level, had a significant effect on the synthesis of ginsenosides. In summary, soil urease, pH, and soil bulk density in agricultural soils can regulate soil physicochemical properties, soil enzymatic activities, and soil bacterial community abundance. These factors are key drivers of the ginseng soil microbial ecology in ginseng cultivation. These studies will provide a scientific basis for subsequent optimization of soil improvement techniques for cultivated ginseng in farmland by improving the soil microbial ecology.

Comparative Study on the Use of Reinforced Concrete Piles and Rock Columns in Weak Foundation Strata in Zambia

All structures require transfer of loads to the competent strata. Where less competent soil strata is encountered, the use of either pile foundations or ground improvement methods is adopted. In Zambia, reinforced concrete pile foundations are the commonly used deep foundations since, to transmit loads to stronger strata by utilizing foundation soil skin friction, end bearing or both, while also guarding against differential settlement. Unfortunately, this has proved to be an expensive construction method and it requires the use of materials processed in high energy consuming industries. Stone columns, among many techniques, are one of the most commonly used soil improvement techniques. Although this ground improvement method is considered to be relatively cheaper than reinforced concrete piles, as it only requires the use of coarse aggregates that are widely available in Zambia, it is yet to be employed in the Zambian construction industry. As such this research aimed at comparing the use of the two construction techniques by using Finite Element Method (FEM) Analysis Software Plaxis V20 (2D and 3D) under similar loading conditions and soil properties (Lusaka West, Zambia). The resulting models and simulations were used for comparison of the various parameters which included axial loading (and lateral bulging for stone columns) for skin friction characteristics of the models. In the case of stone columns, the effects of internal angle of friction, spacing and surcharge settlement behaviour were taken into account to come up with the best performing stone column model. For calibration and validation purposes, a number of physical experiments were modelled and simulated so as to produce models that matched their predecessors as much as possible, then the soil properties were adjusted to match those obtained from a local site in Lusaka West, Zambia. Based on the results, concrete pile foundations were found to endure a larger loading before attaining the ultimate failure as compared to stone columns, but the serviceability loading state of stone columns was quite similar to that of the concrete pile foundation. Hence for structures requiring relatively low serviceability loading state on relatively large ground surface area, stone columns proved to be a reasonable construction alternative for pile foundations.

Comparison of soil improvement techniques on the development of efficient consolidation response

A comprehensive experimental program including two distinct series of consolidation tests was performed on clay specimens prepared at different dry weight proportions including 0%, 1%, 2.5%, 5%, 7.5%, 10% polypropylene fiber or lime by weight mixed with clayey soil. Fiber inclusion into clay resulted in enhancement of compressive strength characteristics, improvement of hydraulic properties that is an advantage for modification of stability and durability properties of clayey soil under loads. Similarly, the higher hydraulic conductivity of clay resulted that will shorthen duration of consolidation settlement, hence, eventually influence completion of plastic consolidation deformation favorably for soft clays. Lime-treatment on clay specimens showed that the compressibility properties are improved such that the strength of clay against loading enhances, exhibits less consolidation deformation under load owing to increase in lime content. On the other hand, clay becomes highly impermeable, displays substantially larger water-resistant properties because of increased lime mass proportion (i.e. time-extension) in clayey soil that results in prolongation of expulsion of excess porewater pressure from clay due to load application, relevant induced stresses. Fiber-inclusion resulted in exhibiting logarithmic decrement with a mild rate of decline while lime-treatment led to exponential reduction with a sharp rate of drop for compression index (Cc), compressibility coefficient (αv), volume compressibility coefficient (mv). Further, fiber-inclusion stimulated exponential and quadratical increment whereas lime-treatment induced exponential decrement for coefficient of consolidation (cv), hydraulic conductivity (k), respectively. As a result, the Cc, αv, mv enhanced on the order of within 10 at average of 80% to 90% with a minimum of 70% by value for both fiber-reinforcement and lime-stabilization soil-stabilization techniques. The cv, k improved on the order of within 10 at average of 75% to 85% by value for fiber-reinforcement whereas dis-improved on the order of within 10 at average of 70% to 80% by value for lime-stabilization.

Comparative Analysis of underconsolidated soil improvement with Pile Raft and Pile Bent Structures on Toll Road Project in Tangerang

Soft soils undergo consolidation when subjected to additional loads, owing to their low shear strength and high compressibility. This research conducts a comparative analysis of soil improvement techniques, specifically examining the application of pile raft and pile bent structures, with a focus on safety factors and construction time. The study employs the finite element method, incorporating hardening soil parameters to simulate the soil behavior and embedded beam parameters to model the pile raft and pile bent structures. The analysis adheres to the SNI Geotechnical 8460:2017 standard for assessing geotechnical safety. The findings of this investigation reveal that the utilization of pile bent structures offers greater efficiency in terms of accelerated construction timelines and favorable safety factors when compared to meticulous soil improvement practices. The latter necessitates an extended duration due to the substantial embankment process, often reaching heights of up to 12 meters, while pile bent structures only require a 3-4 meter embankment as a platform, with the remainder of the structure designed to meet the required elevation. This research underscores the advantages of employing pile bent structures in projects involving underconsolidated soil, offering valuable insights for the construction industry and potentially influencing future engineering practices in similar contexts.

Assessment of Flexural Strengths and Flexural Load Bearing Capacity of Bamboo Grids-Reinforced Soil Beam

Soil improvement techniques have become a major solution to soil related problems. Thus, this paper aims to determine the flexural strengths and flexural load bearing capacity of bamboo grids-reinforced soil beam using standard methods and experiments at 7 days, 14 days, 21 days and, 28 days curing ages. The findings of this study showed that the mean flexural strength of uniaxial bamboo grid reinforced soil beam gave 3.50 N/mm² while flexural strength of biaxial bamboo grid reinforced soil beam gave 3.86 N/mm². The result indicates that biaxial bamboo reinforced soil beam has the tendency to maximize the flexural load bearing capacity of soil beams when compared with the use of uniaxial bamboo grid orientation technique. This paper, therefore, recommends that flexural strength and flexural load bearing capacity of inorganic clays of low to medium plasticity should be improved using biaxial grid type of bamboo grid orientation technique.

Www.ijeit.misuratau.edu.ly ISSN 2410-4256 Paper ID: EN017 Soil Improvement Technique for Pilot Section as New Railway Project in Libya

The construction of embankments on soft saturated soils can be a challenge due to the low shear strength and high compressibility of these soils. The application of reinforced and pile-supported embankments to sustain the imposed dead and traffic loads for train speeds of up to 250 km/h is recently growing in Libya. The aim of this study examine the performance of Geogrid-reinforced embankments with Vibro- stone columns as a ground improvement method adopted in "Pilot Section Al Khoms" subject to cyclic loadings that are applied over a specific area of the embankment to improve strength and provide a safe and economical design for the whole coastal railway. The main result from the load plate test indicates that the stringent performance requirements of the new railway project were met. Furthermore, it was observed that with an increasing number of reinforcement Geogrid layers, enormous cycles of loading could be applied without experiencing excessive deformation and an important reduction in the stress and settlement on the subgrade. The results from field experience, show the project was completed on time and the ground improvement method adopted was employed successfully to reduce the costs of construction maintenance of embankments in the high-speed railway project.

A bio-chemo-hydro-mechanical model of transport, strength and deformation for bio-cementation applications

Bio-cementation through microbially induced calcite precipitation (MICP) has the potential to overcome several technical and environmental limitations of conventional cement-based soil improvement techniques. While a significant amount of research has been directed towards better understanding and controlling MICP processes, there is still a lack of multiphysical formulations that can be used for the design of real geotechnical applications in which both the treatment extent and its strength and deformability need to be evaluated. This paper presents the development and application of a comprehensive bio-chemo-hydro-mechanical model that can be used for designing MICP treatments with the finite element method. To overcome the limitations of current approaches based on elasticity, the formulation involves an elastoplastic constitutive model based on Mohr–Coulomb that can predict the strength increase of MICP-improved soils. The model can easily be calibrated with existing experimental results. The scope of model application is demonstrated through the case of a 2D shallow foundation strengthening. Results reveal that the questions of what level of cementation to target and how to distribute cementation efficiently are of equal importance to ultimately serve the needs of specific geotechnical problems, such as those of bearing capacity.

An Analytical Review on Comparative Analysis of Ground Improvement Using Various Admixtures

Soil improvement in the most sustainable way is the need of the hour and prime importance for the modern construction industry. Most of the time, it has been observed that the soil below the foundation is not mechanically capable of withstanding the load from the structure, and it might cause the failure/collapse of the structure. To prevent it, various significant soil improvement techniques have been introduced, such as mechanical stabilisation, thermal methods, use of admixtures etc. Ground improvement using admixtures involves the addition of various chemical alternatives to the subsoil to enhance its loadbearing capacity. These procedures also give long-term sustainability regarding the soil's bearing capacity. Various potential scholarly works on ground improvement have been done, i.e., the addition of bentonite, kaolinite, bitumen, rice husk ash, pond ash, lime, and cement into the soil, which has been intensely reviewed. From the combined observed experimental results of several researchers presented in this paper, it can be identified how much improvement of a particular soil property can be made by adding several types of admixtures. A clear idea can be generated as to which type of admixture is most suitable for the improvement of a particular type of soil and which soil properties can be improved by the addition of that admixture.