Lime Stabilization Research Articles

Microplastics aging in wastewater treatment plants: Focusing on physicochemical characteristics changes and corresponding environmental risks

Microplastics (MPs) have been frequently detected in effluent wastewater and sludge in wastewater treatment plants (WWTPs), the discharge and agricultural application of which represent a primary source of environmental MPs contamination. As important as quantitative removal is, changes of physicochemical characteristics of MPs (e.g., shapes, sizes, density, crystallinity) in WWTPs are crucial to their environmental behaviors and risks and have not been put enough attention yet. This review is therefore to provide a current overview on the changes of physicochemical characteristics of MPs in WWTPs and their corresponding environmental risks. The changes of physicochemical characteristics as well as the underlying mechanisms of MPs in different successional wastewater and sludge treatment stages that mainly driven by mechanical (e.g., mixing, pumping, filtering), chemical (e.g., flocculation, advanced oxidation, ultraviolet radiation, thermal hydrolysis, incineration and lime stabilization), biological (e.g., activated sludge process, anaerobic digestion, composition) and their combination effects were first recapitulated. Then, the inevitable correlations between physicochemical characteristics of MPs and their environmental behaviors (e.g., migration, adsorption) and risks (e.g., animals, plants, microbes), are comprehensively discussed with particular emphasis on the leaching of additives and physicochemical characteristics that affect the co-exist pollutants behavior of MPs in WWTPs on environmental risks. Finally, knowing the summarized above, some relating unanswered questions and concerns that need to be unveiled in the future are prospected. The physicochemical properties of MPs change after passing through WWTP, leading to subsequent changes in co-contaminant adsorption, migration, and toxicity. This could threaten our ecosystems and human health and must be worth investigating.

Stabilization of Soil Using Fly Ash

Abstract: Soil is the basic foundation for any civil engineering structures. It is required to bear the loads without failure. In some places, soil may be weak which cannot resist the oncoming loads. In such cases, soil stabilization is needed .Numerous methods are available in the literature for soil stabilization, But sometimes, some of the methods like chemical stabilization; lime stabilization etc. adversely affects the chemical composition of the soil. In this study, fly ash mixes with clay soil to investigate the relative strength gain in terms of unconfined compression, bearing capacity and compaction. The effect of fly ash on the geotechnical characteristics of clay-fly ash was investigated by conducting standard Proctor compaction tests, unconfined compression test, CBR tests and permeability test. The tests were performed as per Indian Standard specifications. Index Terms: Soil, Fine Fly Ash Mixture, Soil Stabilization.

Design and development of methodology for construction of thin white topping for rural roads in India

A large proportion of villages in India have been connected with water bound macadam (WBM) or bituminous roads. Rural roads usually have a low volume of traffic, consisting mostly of light transport vehicles with less frequency of heavy traffic. Maintenance of these roads is neglected because of the paucity of funds and the created road asset is in deteriorated condition. The non-availability of suitable soil and aggregates has made projects unviable and cost prohibitive. This aggregate scarcity will increase further as a result of environmental conservation and restriction on mining. There is a need to develop alternative pavement designs to construct sustainable and durable rural roads. The stabilization of soil/aggregate is being used worldwide towards optimal usage of scarce resources. The concepts of soil/aggregate stabilization and Cold In Place Recycling technique provide a comprehensive solution for rehabilitation of existing road and greenfield road construction. Cold In Place Recycling process allows usage of locally available marginal materials. The stabilization process can use a wide range of stabilization agents such as soil-aggregate mix, lime, cement, fly ash, foamed bitumen, emulsion, polymers, and other proprietary chemical stabilizers. Two rural roads are identified under Mukhya Mantri Gram Sadak Yojana Research and Development Scheme. Pavements are designed considering cement treated base. These roads are constructed using the Cold In Place Recycling technique. The existing water bound macadam (WBM)/deteriorated bituminous surface is stabilized with cement. Bituminous concrete and Thin White Topping are provided as wearing course. The performance of pavement is evaluated after 2 years of construction. Also, the balance life of the pavement is checked and the results are satisfactory. The stabilized pavements offer superior strength and longevity, even in extreme climatic conditions, and provide better performance. The design charts for Thin White Topping for rural roads are not available, hence the design charts for Thin White Topping of M30/M35/M40 grade concrete on Cement Treated Base of varying thickness and different subgrade CBR are prepared based on IRC 62-2014 for traffic less than 50 CVPD, 51 to 150 CVPD, and less than 450 CVPD. These charts are ready to use and act as a guide to the Field Engineers. The optimum thickness of Thin White Topping can be selected from the chart for known subgrade CBR and Traffic. The effect of variation of CTB thickness on Thin White Topping thickness can be determined from the chart.

Lime stabilization of clayey landfill base liners: Consolidation behavior and hydraulic properties

Lime soil treatment is a chemical process in which lime (quicklime, hydrated lime or lime slurry) is mixed with the in place subgrade soil and a chemical reaction takes place. The lime reacts with the clay particles in the soil to create a cementitious matrix. The design of landfill base liners including a clay layer as a fluid barrier (i.e. water-resistant impervious layer) requires a neat engineering approach considering, in particular, consolidation behavior as well as hydraulic properties of the clay contained. For sake of safe and stable design of such baseliners under the landfills, the reduction of consolidation settlement in clay when subjected to the accumulated waste load (i.e. superposed action) during operation as well as the accomplishment for ensuring the waterproof of those composite base liners (comprised of multiple different layers) not to allow the penetration of the contaminated water - produced as a result of exothermic reactions occurring in the waste body in landfills – by enabling enhanced isolation from the natural ground is of importance. In light of this, in order to address those two most important design concerns (i.e. Consolidation and Hydraulic Properties of Clay) as well as to in an at- tempt to develop an enhanced clay layer system for landfill baseliners that has a greater bearing capacity (i.e. load resistance), and hence, more robust against settlements, and additionally, possessing improved hydraulic properties by being relatively more water-resistant and greatly impermeable, a series of consolidation tests were performed in the laboratory at different lime contents (lime/lime-clay mixture proportions by weight: 0%, 10%, and 20%) on clay specimens to investigate the stabilization and improvement of clayey landfill baseliners. Lime treatment on clay specimens has shown as a result of the experimental program that the strength of clay against loading improves, and further, exhibits less vertical deformation (settlement) under the load owing to an increase in lime content. Moreover, the clay becomes highly impermeable and displays substantially larger water-resistant properties because of increased lime mass proportion in clayey soil. The findings of the experimental program demonstrate that lime stabilization of the clayey soils in landfill baseliners will benefit the bearing capacity and the imperviousness (water tightness) engineering design properties as compared to standard composite multi-layered landfill baseliner systems.

Linking small-strain stiffness to development of chemical reactions in lime-treated soils

In the context of lime stabilization, this note shows how the development of soil–lime reactions can be linked to the variation of small shear stiffness with time. To determine the evolution of small-strain stiffness, the shear wave velocity was measured by means of bender elements (BE) on a compacted clayey soil treated with 3% quicklime, starting form 2 h after compaction until 98 days of curing. Different methods of signal interpretation were applied with the purpose of highlighting how the peculiarity of lime treated soils affects BE testing results and to provide practical indications for optimizing similar testing on lime-treated soils. The results showed that lime treatment and compaction affect the waveform of the received signal and that measurements should span across a wide range of input frequencies in order to identify an optimal waveform. The small strain shear modulus was found to increase with curing time with a trend that can be related to that of soil–lime chemical reactions, thus representing a promising parameter to monitor the development of soil–lime reactions.

Feasibility of lime and biopolymer treatment for soft clay improvement: a comparative and complementary approach

Highway pavement infrastructure projects which involve soil improvement should be executed, ensuring environmental sustainability. In the present study, guar gum (GG) and lime were assessed for the purpose of soft clay stabilization. The experimental program for the soil stabilization employed a two-stage process. The initial stage involves treatment of the soil with various percentages of lime (3, 5, 7, and 9%) and GG (0.6, 1.0, 1.4, and 1.8%), maintaining the same material acquisition cost and considering curing (0, 7, 14, and 28 days) for the unconfined compressive strength (UCS). In the second experimental stage, a complementary approach in which 3% lime was combined with GG at various percentages (0.1, 0.2, and 0.3%) was employed. The tests conducted include UCS, California bearing ratio (CBR), and strength loss resistance (SLR). Results show that the sole use of lime and GG resulted in significant improvement in the UCS, albeit lime was better. While UCS improved with curing time for the lime-stabilized soil, UCS gain for GG occurred only for up to 7 days curing because biodegradation of GG by microbes in the soil ensues on further curing. Lime-GG stabilization resulted in better UCS and CBR improvement with curing than lime stabilization; however, lime stabilization yielded better SLR. The optimum additive content for strength improvement was obtained at 3% lime + 0.3% GG. Microstructural analysis indicated cementation in the stabilized soil. Predictive models for the UCS were developed based on regression methods. Model evaluation revealed that Gaussian process model provided the best UCS prediction.

A life cycle approach to environmental assessment of wastewater and sludge treatment processes

AbstractLife cycle assessment (LCA) is a tool for determining a product or a process's environmental effects. In this study, LCA evaluates the critical sources of environmental impacts in wastewater treatment plants (WWTPs). The aim of the study is to conduct a comparative LCA of four wastewater treatment (WWT) methods: activated sludge process, sequential batch reactor, constructed wetlands, and up‐flow anaerobic sludge blanket, including the sludge treatment methods: anaerobic digestion (AD), AD with pretreatment, lime stabilization (LS), and LS with energy recovery. Environmental impacts are analysed using the IMPACT 2002+ approach and Simapro 9.1 software using the Ecoinventv3.6 database. The study result shows that the sequential batch reactor has the highest environmental effects because of its high energy consumption. Electricity used for treatment is the primary contributor to environmental impacts. The study helps in evaluating the potential environmental impacts corresponding to a WWTP and identifying the hotspots associated with the process.

Mechanical Properties of Clayey Soil Reinforced with PET Considering the Influence of Lime-Stabilization

Reusing waste plastic can be considered as an important issue in terms of economical as well as environmental concerns. Stabilization of clayey soil is a well-utilized approach to improve the mechanical properties concerning the geotechnical aspects. Meanwhile, the effect of concurrent employment of both lime and waste plastic fibers with different contents and various shapes on mechanical properties of clay is not evident. This research presents the mechanical characteristics of clayey soil reinforced with Plastic Polyethylene Terephthalate (PET). Both unstabilized and lime-stabilized clay are considered as unreinforced materials and the plastic strips and pellets are separately utilized as reinforcement substances. Various tests namely standard Proctor compaction test, point load test (PLT) and drop-weight impact loading test are performed to assess the effect of reinforcement and stabilization on mechanical behavior of clayey soil. The concurrent influences of using PET and adding lime confirm that positive effect of lime stabilization on strength is more meaningful. Meanwhile, the limited content of 1.5% of PET shows the maximum strength for reinforced clayey soil. Generally, reinforcement with strips leads to the exhibition of higher strength based on the point load strength index and more flexibility based on the applied impact loads in comparison with pellet particles.

Durability performance of a lime stabilized expansive soil with egg shell ash as a subsidiary admixture

Stabilization is broadly classified as mechanical and chemical stabilization. Lime stabilization is the most commonly adopted method for stabilising expansive soils. In recent years, lime has been combined with other waste materials for improved performance in stabilization. One such waste is egg shell waste, generated by the poultry industry. Calcination of egg shell waste results in the formation of egg shell ash (ESA) which has a chemical composition very similar to that of quick lime. This investigation focuses on the potential of ESA as an auxiliary additive for lime in the stabilization of expansive soils. The initial consumption of lime of the expansive soil was determined using the Eades and Grim pH test. The lime content in the stabilization process was modified with ESA up to 0.5% in increments of 0.1%. Unconfined compression strength test samples of dimensions 38 mm x 76 mm were cast and cured for a period of 21 days and tested for their strength. The durability of the samples was also evaluated by subjecting the samples to 1, 4, 7, and 10 cycles of wetting and drying. The results of the investigation revealed that 0.2% ESA was the optimal dosage of additive to lime stabilization for improved performance.

Understanding the Impact of Lime Stabilization on Expansive Soil for Grounding and Analysis Adopting LIBS

Stabilization of soil for grounding purposes has been performed by adding different wt% of lime. Electrical breakdown measurements under lightning impulse voltage showed a reduction in breakdown voltage and the time to breakdown with increment in the lime content in the soil. These parameters also increased with curing period for all concentrations of lime of stabilized soil samples. The results show that pH and electrical conductivity of the expansive soil increase as the lime content increases, but decrease with increasing the curing period. Mineralogical and micro-structural analysis has been made by means of X-ray diffraction (XRD) studies and by scanning electron microscope (SEM) analysis. The axial strength obtained from unconfined compressive strength (UCS) analysis, the plasma temperature and the electron number density calculated from Laser Induced Breakdown Spectroscopy (LIBS) data tend to increase with increment in lime content as well as the curing period of the lime stabilized soil. Using univariate analysis, the normalized intensity ratio of Ca II peaks from LIBS spectral data are correlated with lime content in the soil samples at various curing periods. The partial least squares regression (PLSR) technique is successful in determining the soil parameters with the help of LIBS spectral data, at different curing periods with an R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> value greater than 0.95 and the percentage RMSE value smaller than 4%.

Pengaruh Subtitusi Bubuk Cangkang Telur terhadap Batas-batas Konsistensi Tanah Lempung yang Distabilisasi dengan Kapur

This study aimed to investigate the use of eggshell powder (ESP) to replace lime in soil-lime stabilization. Calcite was found in significant quantities in the ESP. The soil consistency limits are commonly used to evaluate the workability and estimate the mechanical properties of stabilized soil. The pH test was used to determine the initial Consumption of Lime (ICL), which was 8%. Several test variations were performed to investigate the effect of ESP replacement on the consistency limits of soil-lime stabilization soil, substituting ESP for a portion or all of the lime content required for stabilization. Soil-lime stabilization decreases the liquid limit, plasticity index, and linear shrinkage of the soil. With lime stabilization, the plasticity index reduced by 60% - 55%. The more lime content was substituted with ESP The greater the plasticity index. However, when all lime content was replaced with ESP, the soil plasticity index reduced by 29% compared to untreated soil. The shrinkage limit of untreated soil was 10.43%; after stabilization with 8% eggshell powder, the shrinkage limit increased by 26% to 13.22%. The shrinkage ratio, volumetric shrinkage, and linear shrinkage, on the other hand, are not significantly reduced. Lime types (hydrated lime and quicklime) have nearly identical behavior in terms of changes in soil plasticity. The eggshell powder can be used for soil stabilization and can affect soil plasticity. However, the changes in plasticity are not as significant as those seen with lime stabilization.

Formulation and optimization of a phosphogypsum – fly ash – lime composite for road construction: A statistical mixture design approach

This paper investigates the valorization of phosphogypsum and fly ash by-products as a road construction material through lime stabilization. To this end, an extreme vertices design was adopted to model the compaction characteristics, mechanical performance at different curing periods and durability upon wetting/drying (W/D) cycles of the mixture. Statistical analysis of the obtained regression models showed that the measured responses decrease with phosphogypsum addition while fly ash and lime cause them to increase. The increasing effect of fly ash addition was especially noticeable on compressive strengths at early ages (7–28 days), whereas at longer curing periods (90–360 days), these were mainly governed by its interaction with lime following the activation of the pozzolanic reaction where phosphogypsum acted as a catalyst to improve fly ash reactivity. However, a negative impact of excess lime beyond a threshold has been noted. The compressive strength at 28 days combined with weight loss upon W/D cycles were used as optimization responses to detect regions of interest, within the design space, where requirements are met for a subbase utilization.

Optimization of lime and fiber content for improvement of clays with different plasticity using response surface method (RSM)

Concurrent stabilization and fiber reinforcement is a common method for improving soft clay characteristics. Enhancements are function of percentage lime, fiber content and length and curing regime. Parallel assessment of these factors on mixture characteristics is arduous and interpretation of the results difficult. Thus, Response Surface Method (RSM) is adopted as a complementary method to reduce the number of tests required and interpretation of observations. In present study effects of plasticity index (10, 17 & 24%), lime content (1, 3 & 5%), percent fiber (0.1, 0.15 & 0.2%), fiber length (6, 12 & 18 mm) and curing period (1, 7 and 28 days) on features of composite mixtures has been explored using uniaxial compression tests. Results show concurrent lime stabilization and random fiber inclusion improves strength and strain characteristics with curing time. Varying clay plasticity resulted in improvement of uniaxial compressive strengths (UCS). RSM method and sensitivity analysis conducted showed lime content is the most and fiber content and length are the least influential factors on UCS and strain at failure. Scanning Electron Microscopy exposed that lime treatment and the formation of chemical compounds develop a coherent matrix binding clay particles and fibers at interfaces resulting in significant improvement in composite strength.

Mechanical and Environmental Performance of Eggshell Lime for Expansive Soils Improvement

Efficient and environmentally friendly alternative binders for expansive soils improvement are needed to practice sustainable geotechnics. This study evaluates the viability of a lime produced from eggshell waste as a green stabilization binder for expansive soils. Three contributions to the literature were achieved: (i) a comparison of the swelling, strength, stiffness, plasticity, and morphology of expansive soils stabilized with hydrated eggshell lime and hydrated industrial lime (i.e. commercially available lime), (ii) a statistical analysis of lime stabilization for swelling control and (iii) a life cycle assessment of eggshell lime versus industrial lime. Free-swell, unconfined compression, stiffness and Atterberg limits tests, and environmental assessment were performed to analyze the bentonite-kaolin-lime blends. Different proportions of bentonite-kaolin, dry density, lime content, and curing time were evaluated. Swelling data was correlated with the porosity/lime index. Results indicate that the alternative binder is a suitable option to improve the mechanical and swelling behavior of expansive soils, presenting higher strength and a reduction in expansion for all analyzed conditions, when compared to the industrial lime. Statistical analyses showed that bentonite content, lime content and dry unit weight factors should be focused for swelling reduction. For both studied limes, the adjusted porosity/lime index was an appropriate parameter to evaluate the swelling of stabilized soils. Life cycle assessment revealed that the alternative binder is a sustainable option as it avoids limestone mineral extraction and improvement.

Insights into deep decline of As(III) leachability induced by As(III) partial oxidation during lime stabilization of As–Ca sludge

The enhancing effect of As(III) oxidation on As stabilization by lime is routinely attributed to the lower solubility of Ca arsenates than Ca arsenites. However, this routine explanation is insufficient for the scenario of As(III) partial oxidation, in which Ca arsenites still predominate As leachability due to the relatively high solubility. In this study, an As–Ca sludge with a high As(III) content (96 g/kg, 55% of the As(tot)) was treated by oxidant–lime to clarify the positive effect of As(III) partial oxidation. Lime alone only reduced As(tot) leaching concentrations from 541 to 4.9 mg/L (4.3 mg/L of As(III) and 0.6 mg/L of As(V)), failing to meet the regulatory limit (2.5 mg/L). After partial oxidation of As(III), lime treatment could further reduce As(III) leaching concentrations from 4.3 to below 1.9 mg/L, whereas As(V) remained stable at about 0.6 mg/L. Qualitative and quantitative analyses based on XRD, SEM–EDS, TG, and thermodynamic modeling suggested that the solubility of newly-formed amorphous Ca arsenites (CaHAsIIIO3•xH2O) after lime treatment determined the final As(III) leachability. The CaHAsIIIO3•xH2O formed at lower As(III) contents due to As(III) partial oxidation had lower solubility products and possibly higher crystallinity, resulting in the lower As(III) leachability. This study provides new insights into the role of As(III) partial oxidation in deep decline of As(III) leachability during lime stabilization, guiding the treatment of As–Ca sludge as well as other As(III)-bearing solid wastes.

Comparative Assessment of Deformation Under Plate Bearing Test and CBR Test for Subgrade Soil

A significant variation in the strength and deformation behavior of subgrade soil when tested in the laboratory and in the field. However, correlation of such variables is essential to evaluate the quality of the constructed subgrade. An attempt has been made in the present investigation to assess the deformation of control and stabilized subgrade soil in the laboratory and in the field. California bearing ratio (CBR) test was conducted in the laboratory and the static plate bearing test (PBT) was conducted in the field. Subgrade soil samples were stabilized with 6% lime, 17 % Cationic Emulsion, and combination of lime and emulsion. Similar stabilization was conducted at test sections in the field. The behavior of the control and stabilized soil in deformation under static PBT in the field and CBR in the laboratory was monitored and evaluated. It was noticed that polynomial correlation exists with high coefficient of determination between laboratory and field deformation for stabilized soil. It was observed that the deformation under CBR test decreased after implication of lime by (96 and 88) % for unsoaked and soaked testing conditions respectively. The deformation decreases by (92 and 85.6) % for unsoaked and soaked testing conditions respectively when emulsion was implemented. The deformation decreases by (91 and 88) % for unsoaked and soaked testing conditions respectively when combined stabilization was implemented. However, the deformation under PBT decreases by (75, 56, and 50) % for lime, emulsion, and combined stabilization processes respectively. It was concluded that testing condition (soaked or unsoaked) has no significant impact on the deformation of stabilized soil while it has a significant influence on the deformation of untreated soil under CBR test. On the other hand, the deformation of control soil shows no significant variation among field and laboratory testing in the model, however, the stabilized soil samples exhibit higher influence of field deformation on the polynomial models.

Transformation of Silver Nanoparticles (AgNPs) during Lime Treatment of Wastewater Sludge and Their Impact on Soil Bacteria.

This study investigated the impact of lime stabilization on the fate and transformation of AgNPs. It also evaluated the changes in the population and diversity of the five most relevant bacterial phyla in soil after applying lime-stabilized sludge containing AgNPs. The study was performed by spiking an environmentally relevant concentration of AgNPs (2 mg AgNPs/g TS) in sludge, applying lime stabilization to increase pH to above 12 for two hours, and applying lime-treated sludge to soil samples. Transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) were used to investigate the morphological and compositional changes of AgNPs during lime stabilization. After the application of lime stabilized sludge to the soil, soil samples were periodically analyzed for total genomic DNA and changes in bacterial phyla diversity using quantitative polymerase chain reaction (qPCR). The results showed that lime treatment effectively removed AgNPs from the aqueous phase, and AgNPs were deposited on the lime molecules. The results revealed that AgNPs did not significantly impact the presence and diversity of the assessed phyla in the soil. However, lime stabilized sludge with AgNPs affected the abundance of each phylum over time. No significant effects on the soil total organic carbon (TOC), heterotrophic plate count (HPC), and percentage of the live cells were observed.

The Effects of Geocell Height and Lime Stabilization on Unpaved Road Settlements at Different Water Contents

In this study, lime stabilization and geocell reinforcement methods were investigated for a clayey subgrade of unpaved road at different water contents. This study is especially important in terms of determining the soil improvement method for road construction on wet lands. The effects of the geocell height (50, 100, 150, and 200 mm) and lime content (3, 6, and 12%) on the settlement of the subgrade soil at different water contents (25, 28, 30, 32, and 35%) were analyzed. Accordingly, a large scale plate loading test was designed, and it is utilized to achieve loading-settlement curves. The bearing capacity and modulus of subgrade (k) of soil were determined. It was detected that the geocell height and lime content have different effects at different water contents, and the modulus of subgrade reaction became stable beyond a constant height of the geocell. It was understood that none of these two improvements did not meet the Highways Technical Specifications. It is detected that at least these two improvement techniques are needed to be applied together to meet the specifications for the soil examined in this study.

Effect of Lime Stabilization and Partial Clinoptilolite Zeolite Replacement on the Behavior of a Silt-Sized Low-Plasticity Soil Subjected to Freezing–Thawing Cycles

Soil stabilization, through either physical or chemical techniques of coating-cementation development, is a commonly adopted practice in geotechnical and transportation engineering projects used to strengthen soils and mitigate negative geo-environmental impacts. This can be particularly important in enhancing the mechanical properties of soils which are prone to degradation of their response because of freezing and thawing actions. It was attempted in this research study to examine the effect of lime–zeolite stabilization on the behavior of a silt-sized natural soil of low plasticity, by performing standard compaction tests as well as unconfined compressive experiments evaluating the strength of the composite samples. The natural soil mixed with various contents of lime and zeolite partial replacement was subjected to consecutive freezing and thawing cycles. The results from the study showed significant improvement of the mechanical performance of the treated soil when mixed with lime partially replaced with zeolite in terms of strength and durability and, based on scanning electron microscopic images, additional insights were attempted to be obtained on the microstructure of the specimens subjected to temperature changes.

Stabilization of B.C. Soil by Using Chemicals and Fly Ash

Black cotton soils are very susceptible to detrimental volumetric changes with changes in moisture. This behaviour of soil is attributed to the presence of mineral montmorillonite which has an expanding lattice. Black cotton soils because of their specific physical and chemical make are subjected to volume changes. In many countries including India, these soils are so extensive that alteration of highway routes to avoid the material is virtually impossible. Various remedial measures like soil replacement, prewetting, moisture control, lime stabilization etc. have been practiced with varied degrees of success. Extensive research is going on to find the solutions to Black cotton soils. Recent investigations on chemical stabilisation revealed that electrolytes like Calcium Sulphate, Calcium Carbonate, Zinc Chloride can be used in place of conventionally used lime, due to their ability to supply adequate cations. Fly ash is a waste by product from thermal power plants consuming thousands hectors of precious land for its disposal and also causing severe health and environmental hazards. This work presents the results of an experimental program undertaken to investigate the effect of Calcium Sulphate, Calcium Carbonate, Zinc Chloride and fly ash at different percentages on properties of black cotton soil. Atterbergs Limit of subgrade soil effect of addition of Fly Ash and Chemicals on CBR ,MDD ,OMC, From the results it is observed that 2% of Zinc Chloride and 12% of Fly ash improves the properties of black cotton soil as compared to Calcium sulphate &amp; Calcium Carbonate. The conclusion drawn from this investigation is that a combination of 2% of chemicals and 12% of fly ash is more effective in improving the properties of black cotton soil.