Lime Stabilization Research Articles

Stabilization strategy of normal and chrome tanning effluent mixed subsoil: a novelty to enhance the soil characteristics

Soil stabilisation is a unique method to effectively and accurately find a solution to the issues caused by loose subsoil. This research investigates the problems of uncontrolled industrial effluent disposal, mainly from tannery enterprises, which presents severe environmental problems in emerging nations due to soil properties changing and large regions being unfit for cultivation and human habitation. The study uses Atterberg's limits, sieve analysis, and direct shear testing to examine the effects of untreated tannery effluents on soil parameters. The findings show that the soil's shear strength, moisture content, and flexibility have all significantly decreased. Lime and waste stone powder were added to lessen these impacts, and this improved soil stability was shown by an increase in the values of all the variables. For efficient soil remediation, the study suggests using waste stone powder and lime in the following proportions: 0%, 3%, 6%, and 9%. Combining lime stabilisation methods with industrial by-products like slag and fly ash opens up new possibilities for enhancing the geotechnical characteristics of polluted soils. This study emphasises how important it is to use customised geotechnical design techniques to handle soil contamination issues in infrastructure and foundation projects, especially in areas where the leather industry predominates.

Utilization of calcium carbide residue based soil stabilizer in road construction: Strength, environmental impact, and field application

This research paper delves into the utilization of calcium carbide residue (CCR)based stabilizer (designated as CSC) in road subgrade soil stabilization, with a comprehensive evaluation of its mechanical strength, environmental safety, and efficacy in field applications. Amid growing environmental concerns and the push for sustainable construction materials, this study presents an innovative approach by repurposing CCR, a by-product of the acetylene production process, in enhancing the structural integrity of road foundations. Through a series of laboratory tests, the investigation reveals significant improvements in the unconfined compressive strength (UCS) and California bearing ratio (CBR) of CSC-stabilized soils, compared to traditional lime stabilization methods. The field test DCPI results indicate that the CBR value of the field test CSC stabilised soil is 50.19% after three days, whereas the CBR value of the field test lime stabilised soil is only 29.51% after the same period. The CBR value of the CSC stabilised soil is significantly higher than that of the lime stabilised soil. This study also tested the leachate of the stabilised soil, analysing the concentration of heavy metals. The results indicated that the leachate from the stabilised soil complies with heavy metal leaching standards, demonstrating the ecological benefits of CSC utilisation. Furthermore, field experiments conducted on the G312 National Highway in Jiangsu Province, China, further validated the laboratory test results. The findings from the field trials indicated that sections stabilised with CSC exhibited superior performance in terms of reduced soil deformation and enhanced load-bearing capacity. Additionally, a life cycle carbon emission analysis was conducted for the field trial section, comparing the carbon emissions of the CSC binder with those of the lime binder throughout the entire life cycle of road construction. The results from the trial section demonstrated that the use of the CSC binder significantly reduced carbon emissions. The study underscores the potential of CSC as a cost-effective, environmentally friendly stabilizing agent, offering a pragmatic solution to the dual challenges of industrial waste management and soil stabilization in road construction.

Lime Stabilization of Tropical Soil for Resilient Pavements: Mechanical, Microscopic, and Mineralogical Characteristics.

Lime stabilization is a sustainable technique due to its use of local materials, increased durability, reduced maintenance, and improved resistance to water action. This paper examines the impact of lime stabilization on the mechanical, microscopic, and mineralogical properties of a tropical soil. Two types of lime, calcitic and dolomitic, were tested at 3% and 5% by weight. Compressive, indirect tensile and flexural test results and statistical analysis revealed that calcitic lime mixtures had higher strength and stiffness, whereas dolomitic lime mixtures exhibited greater deformability with higher tensile strain at break. Scanning electron microscopy indicated that the soil's porous matrix closed within 7 days for both lime types due to flocculation, with increased matrix interlocking over time. The calcitic lime mixture developed a more closed matrix compared to the dolomitic lime, which showed weaker cementing. X-ray diffraction analysis indicated higher consumption of clay minerals and a notable reduction in calcium hydroxide peaks in the lime-treated soils. The study concludes that calcitic lime provides better pavement performance for stabilizing the soil, enhancing its engineering properties while also being sustainable by reducing the need for raw material extraction and improving resilience to climate-related issues such as floods.

Exploring fecal sludge treatment technologies in humanitarian settings at Cox’s Bazar, Bangladesh: a comprehensive assessment of treatment efficiency through characterization of fecal sludge

IntroductionEfficient treatment of fecal sludge in densely populated settings is essential as it has a direct impact on public health and the environment. This study presents a comprehensive assessment of fecal sludge treatment technologies in Rohingya camps at Cox’s Bazar, Bangladesh, focusing on removal efficiencies and compliance with regulatory standards.MethodsSeventeen treatment plants of five different technologies were evaluated based on removal efficiency and standard discharge guidelines for various physicochemical and microbiological parameters.ResultsWaste Stabilization Pond (WSP) was the top performer compared to four other different treatment technologies evaluated, achieving notable removal rates: 97.3% reduction in E. coli, 100% in helminth eggs, 98.3% for COD, 97.8% for BOD, 98.7% for TSS, 92.1% for TS, 82.8% for phosphate, and 93.3% for total nitrogen. Lime Stabilization Ponds showed lower removal rates, except for E. coli (98.9%), with reductions of 99.7% for helminth eggs, 81.6% for COD, 80.9% for BOD, 86.3% for TSS, 68.6% for TS, and 49.2% for phosphate. Upflow Filters demonstrated good removal efficiencies for E. coli (99.7%), TSS (95.9%), COD (91.7%), BOD (93.5%), and helminth eggs (93.7%). WSP consistently outperformed other technologies across all seasons. Despite these, none of the technologies fully met discharge standards.DiscussionThese findings highlight the need for a comprehensive approach, the combination of physicochemical and biological processes, to enhance efficacy. Promoting improved fecal sludge management technologies through awareness campaigns and technical support can mitigate environmental health risks in densely populated humanitarian settings.

Multi-scale investigation on curing time effect of lime stabilized red mudstone as fill material for high-speed railway subgrade

The utilisation of red mudstone waste as subgrade fill material after lime stabilization can meet the requirements of green development. This study aims at investigating the lime stabilization effect on the changes in mechanical properties and microstructure of compacted red mudstone fill material, with particular emphasis on the curing time effect. Red mudstone fill material were stabilized by 4 % lime, and the unconfined compressive strength, direct shear strength and microstructure of the lime-stabilized fill material specimens were determined at various curing times. Results show that the lime stabilization can significantly improve the unconfined compressive strength, modulus and direct shear strength and effectively mitigate the water sensitivity of the red mudstone fill material. The density function curve of the saturated red mudstone fill material shows monomodal characteristic, but the saturated lime stabilized fill material still maintains bimodal characteristic even with only one day of curing. The microstructure modification induced by lime stabilization mainly results from the rapid flocculation of soil particles and the formation of hydration product. During curing, the percentage of the nano-pores increases, mainly attributes to the formation of C-A-S-H which fills the micro-pores gradually.

Micronized PET as a green additive for lime stabilization of swelling soil

The use of Polyethylene Terephthalate (PET) as an additive in the stabilization of swelling soils is a sustainable option considering the increasing environmental pollution caused by improper disposal of plastic waste. Given the limited capacity of recycling programs, incorporating these materials in construction can be a viable solution. In the conducted study, compacted mixtures of soil-lime-PET were prepared at different dry unit weights (14, 15 and 16 kN/m³). Micronized PET was used with percentages of 5% and 10%, while hydrated lime was added at 0%, 2%, 4%, and 6%, both by dry mass. These mixtures were subjected to one-dimensional swelling tests. The results showed that the PET content, lime content, and porosity are significant factors influencing the behavior of compacted mixtures. The index porosity/volumetric lime content adjusted by an exponent (ƞ/(Liv)-0,26) can link the one-dimensional swelling behavior. The combination of both materials creates a sustainable solution for controlling soil swelling.

Experimental evaluation of stress history effect on compressibility characteristics of lime-stabilized expansive soils

ABSTRACT Lime stabilization has long been identified as an effective method for reducing the swelling potential of expansive soils. Despite numerous studies evaluating the volumetric behaviour of lime-stabilized expansive soils, the influence of stress history variations on deformation characteristics of these soils has not been adequately explored. This study specifically evaluates the impact of stress history conditions on compressibility characteristics of lime-stabilized expansive soils, with special attention to the rebound index at different loading stages. In this regard, one-dimensional consolidation-swell tests were conducted on samples containing different lime percentages (3% to 12%) under various stress history conditions. To include different stress history conditions, overconsolidation ratio (OCR), seating pressure, and loading step were varied during the induction of stress history in the samples. Results showed that OCR and seating pressure significantly influenced both the rebound (increased up to 118%) and compression indices (decreased up to 53%), while the loading step had a negligible impact on the compressibility properties of stabilized soils. Additionally, when comparing the relative importance of investigated parameters, it was revealed that, OCR had the highest influence on the rebound index (up to 118.0% increase), while the compression index was most significantly affected by lime percentage (up to 61.4% decrease).

Biological feasibility of discharge a local WTTP sludge to sewer network and centralized WWTP; a case study: Tehran, Iran

Over the recent years, ever-increasing population growth and higher wastewater production has been a challenge for decentralized wastewater treatment plants (WWTPs). In addition, sludge treatment due to high cost for equipment and place make authorities to find a sustainable approach in both of economical and technical perspectives. One of the proposed solutions is transferring the sludge produced from decentralized WWTP to centralized WWTP. However, the appropriate proportional ratio of raw sludge to raw sewage is a challenge, otherwise, it make anaerobic conditions and sewage rotting along the sewer network based on permissible limit of dihydrogen sulfide (H2S) gas (5 ppm). In the present study, seven reactors with different ratios of sludge to raw sewage (0, 15, 20, 25, 50, 75, 100) were used to stimulate the feasibility of transferring Shahrake Gharb WWTP sludge along the wastewater transfer pipe to the centralized sewage treatment south Tehran WWTP plant in Tehran, Iran. The septic situation and H2S emission of different reactors within 7 h (Time to reach the compound in the south treatment plant) was analyzed by gas meter. The results indicated that the optimum ratio of sludge to raw sewage was 15% without H2S production during 7 h. In addition, due to the high volume of sludge produced by the Shahrake Gharb WWTP, the optimal ratio of lime to total solids (TS) in sludge (gr/gr) (0.6) increased the sludge loading rate from 15 to 30% without any H2S emission during the stimulation study period. Therefore, the lime stabilization and transfer of sludge from a decentralized WWTP to a centralized WWTP is a feasible way to manage the sludge and enhance the treatment capacity in local WWTP.

Stabilization of Expansive Soils Using Flyash

Abstract: Soil plays an essential role in the construction of any civil engineering structure. It must be able to withstand the loads without breaking down. In some areas, the soil may not be strong enough to withstand the incoming loads. To address this, there are many methods of soil stabilization available, but some of these methods, such as chemical stabilization, lime stabilization, etc., can have an adverse effect on the soil's chemical composition. In this paper, we will be looking at the effects of fly ash on the strength gain of an expansive clay soil when combined with different percentages of fly ash, such as 0%, 5%, 10%, 15%, 20%, and 25%. We will also be looking at tests to determine the strength gain of the soil with and without fly ash. The results of the laboratory study will show that adding fly ash to the expansive clay soil reduces the soil's plasticity index and increases its MDD. The expansive clayey soil's strength characteristics have improved.

Cement and Lime Stabilization Effect on the Evolutivity of an Expansive Overconsolidated Clay

Cement and Lime Stabilization Effect on the Evolutivity of an Expansive Overconsolidated Clay

Mechanical Strength and Microstructure of Soft Soil Stabilized with Cement, Lime, and Metakaolin-Based Geopolymer Stabilizers

Soft soils require particular consideration when designing civil engineering structures due to their high compressibility, low shear strength, and permeability. Using chemical additives and geopolymers to stabilize soft soils is a practical approach to improve their engineering properties. The objective of the study was to explore the use of conventional stabilizers alongside metakaolin-based geopolymers. This study also aimed to investigate the compaction characteristics, mechanical strength, shear behavior, and microstructure of stabilized soft soil. The compaction test was carried out using various amounts of cement (6%, 8%, and 10%) and metakaolin (3%, 5%, and 7%) based on the dry weight of the soil. Cement, lime, and geopolymer were added to the soft soil at 15% of the dry weight of the soil for triaxial shear tests. The compaction test results indicated that the stabilized soil exhibited the highest maximum dry density at 8% cement content. Adding metakaolin (MK) to the cement-modified soil decreased the maximum dry density, smoothed the compaction curve, and increased the optimum moisture content. The unconfined compressive strength (UCS) test revealed that cement-stabilized soil had the highest yield stress, while adding MK to the cement-modified soil reduced the yield stress after 7 days of curing. Compared to untreated soft soil, there was a significant increase in shear strength parameters for cement-, metakaolin-, and lime-stabilized soil. This study demonstrates that adding chemical additives and geopolymers can improve the soft soil’s compaction characteristics, mechanical strength, and shear strength parameters.

Determination of the Percentage Ca(OH)2 Lime Stabilization Material for Weathered Clay Shale as Road Subgrade on Serang – Panimbang Toll Road Section III STA 57+200

Determination of the Percentage Ca(OH)2 Lime Stabilization Material for Weathered Clay Shale as Road Subgrade on Serang – Panimbang Toll Road Section III STA 57+200

Investigation on the Engineering Properties of Peat Soil Stabilised Using Lime Stabilisation and Alkaline Activation

Peat soil is typically classified as a problematic soil due to its expansive behaviour that possesses geotechnical drawbacks. Thus, the condition of peat soil must be improved prior to any construction works. Stabilisation of peat soil can be done via chemical stabilisation and alkaline activation while incorporating industrial by-products or wastes as addictive. This study aims to investigate the effect of press mud as an additive in lime-stabilized and alkaline activator-stabilized peat soils. Press mud is a by-product of sugarcane juice filtering. The lime adopted is at 3 % and 5.5 % while the alkaline activator is used in cold and warm condition. A total of 5 percentages of press mud have been employed, namely 0%, 0.25%, 0.5%, 1% and 2%. The investigations revealed that regardless of the percentage of lime adopted, the optimum moisture content increases while the maximum dry density decreases when the percentage of press mud incorporated is increased. However, when the lime content is increased, the optimum moisture content increases significantly. The UCS of lime-stabilised peat soil sample achieved the greatest strength improvement when the lime and press mud is used at 5.5% and 0.25%, respectively. In contrast, the unconfined compressive strength (UCS) of 3% lime-stabilised peat soil samples with or without press mud shows comparable 28-day strength. On the other hand, the UCS of peat soil stabilised with alkaline activator shows significant improvement, while addition of press mud further improves the strength. Nonetheless, using warm alkaline activator improves the early strength development but cold alkaline activator results in higher 28-day UCS.

The experimental procedures of sand and lime as base soil stabilization materials on the modified proctor values for flexible pavement construction

During road construction, one of the major challenges encountered is dealing with weak subgrade soil, specifically expansive soil that experiences volume changes due to variations in moisture content. Lime stabilization is a widely used method for improving post-construction stability, offering cost savings, and reducing environmental impact. This study reviews various methods for creating soil-lime mixtures, comparing testing methods. Effective soil stabilization leads to improved construction outcomes, cost reduction, and minimized environmental impact. Soil characteristics, including Maximum Dry Density (MDD) and Optimum Moisture Content (OMC) value, are important factors in determining suitability for construction. Therefore, this study focused on soil characterization, grain analysis, Atterberg limits, and modified compaction before and after lime as well as sand stabilization. This study also determined soil characteristics, grain gradation, Atterberg limit, and modified compaction, and also developed implementation methods and budget plans for stabilized earthworks. Subsequently, the tests included moisture content, density, specific gravity (Gs), sieve analysis, grain analysis with a hydrometer, Atterberg limits, and modified compaction. The tests were conducted with varying percentages of sand (20 %) and lime (5 %, 10 %, 15 %, and 20 % of soil dry weight). Original soil moisture content value (w) = 53.70 %, Wet soil unit weight (γ) = 1.69 gr/cm3, Gs = 2.69, The original soil is classified into A-2–7 as (silty gravel or clay and sand) according to AASHTO.•This method shows the effect of sand and lime as base stabilization materials.•This method examines the roles of modified proctor on the flexible pavement.•This study explores MDD and OMC for curing times of 1, 7, and 14 days.

Effects of the Types and Amounts of Clay Minerals on Durability of Lime-Stabilized Clay Soils

Although the interaction between clay minerals and lime is the most effective factor in lime stabilization techniques, it has not been deeply evaluated. This research study investigated the microstructural characteristics of lime-stabilized Bentonite and Kaolin soils using X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray (EDX) analyses. To consider the variation in clay mineralogy, these soils were mixed at varied ratios, stabilized, and then subjected to a durability process. The microstructural findings showed that the pozzolanic reactions with lime did not occur or occurred at a low level for Bentonite soil. However, they occurred at a very high level for Kaolin soil. The durability test confirmed the microstructural results and showed that the samples in which Bentonite soil had a share of 40 to 100% by dry weight of the soil did not last with any percent of lime. When the Kaolin soil content reached 100% by dry weight of the soil, the specimens lasted in the best possible way, even with 4% of the lime. This study concluded that the determination of optimum lime content based on the amounts and types of soil clay minerals is an important innovation for geotechnical projects and may be very cost-effective.

Effect of surcharge loads during curing of lime-stabilised Cochin marine clay

Marine clays possess poor engineering properties and need to be improved prior to any construction activities. Lime stabilisation is a widely adopted method of chemical stabilisation for such types of soils. This paper evaluates the effect of surcharge loads during curing of lime stabilisation of Cochin marine clays. In the case of lime-stabilised soil cured under surcharge loads, it is necessary to consider two processes – that is, cementation and consolidation—along which the structures of stabilised soils evolve. These two processes are interrelated and cannot be considered separately, especially in the early stages of curing when significant structural changes occur. This study investigated the strength and deformation characteristics of lime-stabilised Cochin marine clay subjected to surcharge loading during curing. The marine clay with 6% lime was subjected to surcharge loads of 20, 40 and 60 kPa for different curing periods up to 180 days. The effects of surcharge loading on shear strength and compressibility characteristics were evaluated at different curing periods.

Shear strength and durability against wetting and drying cycles of lime-stabilised laterite soil as subgrade

Laterite soil is commonly used as a fill or pavement material. However, it tends to lose its natural bonding and experiences large deformation when subjected to cyclic rainy (wet) and hot (dry) seasons. This leads to cracking and deflection of road pavement. It has long been known that lime stabilisation can improve the engineering properties of laterite soils. Unconfined Compressive Strength (UCS) tests at different curing periods (0, 3, 7, 14, and 28 days) were conducted with various percentages of lime (3%, 5%, 7%, and 9%). The durability of stabilised soil against wet and dry cycles was also evaluated. In addition, the variation of shear strength parameters during the Consolidated Undrained (CU) triaxial test under different confining pressures has been presented. Microstructural analyses showed an increased soil strength due to the formation of calcium silicate hydrate (CSH) and calcium aluminate hydrate (CAH).

Techno-economic evaluation of biofertilizer production using wastewater biosolids: case study from municipal wastewater treatment plants in northwest region of Russia

The continuous and rapid growth of sewage sludge (biosolids) from wastewater treatment plants (WWTPs) poses both economic and environmental challenges. In many cities of Russia, the situation has exacerbated with time. In this study, three state-of-the-art biosolid management technologies, namely windrow composting (WC), tunnel composting (TC), and lime stabilization (LS), were evaluated for their economic feasibility to produce commercially biofertilizers from WWTP-derived biosolids. Based on an annual discharge of 22,000 m3 of dewatered biosolids from the case WWTP, about 29,785, 22,453, and 35,056 m3 biofertilizers could be produced through WC, TC, and LS, respectively. Analysis showed the selected WC, TC, and LS technological options to be feasible if the selling price of the produced biofertilizer would be maintained at 19 EUR/m3 for WC and LS, and 77 EUR/m3 for TC. The discounted payback period (DPP) of WC, LS, and TC would be 3.1, 18.1, and 25.3 years, respectively, with an IRR (internal rate of return) of 10%. The key characteristics of the treated WWTP-derived biosolids were found to be good enough to meet the existing environmental laws, standards, and regulations in Russia. From an investment perspective, this study is useful in developing WWTP-derived biosolids for biofertilizer production at enterprise level.

From Waste to Resources: Sewage Sludges from the Citrus Processing Industry to Improve Soil Fertility and Performance of Lettuce (Lactuca sativa L.)

The citrus industry produces a large number of sludges as a consequence of citrus wastewater treatment. The correct disposal of citrus sewage sludges (CSSs) has been attempted using anaerobic digestion, aerobic digestion, and lime stabilization. However, since CSSs hold nitrogen, phosphorus, and other macronutrients required by crops, in line with the circular economy principles, they could be utilized for agricultural purposes, such as organic fertilizer. The aim of this study was to assess the effect of CSSs supplied at different doses on soil fertility and lettuce performance. To this end, a pot experiment was established. The soil was amended with CSSs at three different concentrations (2.5, 5, 10 t ha−1). After 46 days of lettuce growth, the experiment was stopped, and soils and plants were analyzed. Soil amended with CSSs showed an increase in total organic C ranging from 7% to 11%. Additionally, available P increased but only at the highest CSS dose. The addition of CSSs affected the biochemical properties of soil, but a univocal trend related to the number of CSSs applied was not found. Microbial biomass C increased only with the highest dose of CSS applied, while the metabolic quotient (qCO2) decreased. Such a positive effect on soil fertility and soil microorganisms, in turn, lead to an increase in lettuce biomass. Moreover, results indicated that following CSS addition, lettuce crops adsorbed more N in leaves than in roots, whereas P, Ca, Mg, K, and Na showed an opposite pattern and increased more consistently in roots. In conclusion, amendment with CSSs enhances soil fertility by increasing, regardless of CSS dose, total organic C, and, at the highest dose, P availability and microbial biomass C. Such improvement in soil fertility, in turn, increases lettuce biomass production without affecting its quality, i.e., alteration of the (K + Na)/(Ca + Mg) ratio.

Swelling of sulfate-bearing soil: A case study of A1 highway pavement failure

Lime stabilization is one of the most commonly used methods for improving weak road subgrades, but it becomes very problematic in sulfate-bearing soils. This article presents results of a case study in which the sulfate attack was the most probable reason for a significant deformation of a highway pavement founded on lime-stabilized Doggerian clay. Macroscopic analysis revealed partial degradation of the concrete structure, a larger extent of stabilization than designed, and large gypsum crystals in the native soil. Chemical tests indicated a very high content of sulfates in the soil (> 10,000 mg/kg of SO4) and in the groundwater (> 3,000 mg/l of SO42-). The maximum free swelling strain (εvolmax = 3–6%) and the swelling pressure (pcmax = 56 kPa) of the clay, determined in the Wasiliew apparatus and the oedometer tests, were not large enough to be considered as the only cause of the pavement damage. Sand-cement and clay-lime mixtures, which simulated stabilized soil layers in the road profile, were observed for several months in oedometric tests, under various loading conditions. The swelling of Sa-Cem was negligible, but the Cl-Lim mixtures turned out to be much more expansive than the natural soil (εvolmax up to 21%, pcmax = 230 kPa) with a much longer duration of volume increase. The samples were flooded with distilled water or hard groundwater to clarify whether the constant access of the material to sulfates is important in the swelling process, but the results were unequivocal. X-ray diffraction revealed that the addition of lime resulted in the formation of secondary minerals: butlerite, portlandite, and ettringite. The presence and swelling of ettringite in the stabilized sub-base soil layers was eventually agreed to be the most probable reason for the pavement deformation. These results indicate the need to introduce an obligatory investigation of the level of sulfates in clayey subbase soils subject to lime stabilization.