Sustainable Stabilization of Lateritic Soil from Ranchi District, Jharkhand using Lime-Fly Ash Blends

Sustainable Stabilization of Lateritic Soil from Ranchi District, Jharkhand using Lime-Fly Ash Blends

Harsh Raj

B. Tech ( NIT Warangal, Telangana)

Abstract : Lateritic soils extensively found in the Ranchi district of Ranchi are widely used as subgrade material in rural and semi-urban infrastructure projects. However, these soils often exhibit moderate to high plasticity, low bearing capacity, and significant moisture susceptibility, leading to premature pavement distress and foundation settlement. Considering the rapid infrastructural development in the Ranchi region, there is a need for sustainable and cost-effective soil improvement techniques. This study investigates the stabilization of locally sourced lateritic soil from Ranchi using lime and fly ash blends. Laboratory experiments were conducted by incorporating varying percentages of lime (28%) and fly ash (520%) into the natural soil. Engineering properties were evaluated through Atterberg limits, Standard Proctor compaction, Unconfined Compressive Strength (UCS), and California Bearing Ratio (CBR) tests. The results demonstrate a considerable reduction in plasticity index and improvement in strength and load-bearing capacity with the addition of stabilizers. The combined limefly ash treatment showed enhanced performance compared to individual additives. The findings indicate that limefly ash stabilization is an effective and sustainable ground improvement technique suitable for road subgrades and light foundation works in the Ranchi region, promoting the utilization of industrial by-products and supporting sustainable infrastructure development in Jharkhand.

INTRODUCTION :

Jharkhand is a mineral-rich state located in eastern India, characterized by plateau topography, undulating terrain, and predominantly lateritic and red soils. Large parts of the state, especially the central and southern plateau regions, are covered with weathered residual soils derived from igneous and metamorphic rocks. In districts such as Ranchi, Khunti, Gumla, and Simdega, lateritic soils are widely encountered and extensively used in local construction works due to their availability and low transportation cost. The state has witnessed significant growth in infrastructure development over the past decade, including expansion of rural road networks, urban development projects, and industrial corridors. However, the engineering performance of locally available soils remains a major concern. Lateritic soils in Jharkhand often exhibit variable gradation, moderate to high plasticity, and strength reduction under saturated conditions, particularly during the monsoon season. Heavy rainfall combined with inadequate drainage frequently results in reduced bearing capacity of subgrade layers, leading to pavement distress, rutting, and settlement issues. Given the economic constraints in many rural and semi-urban areas of Jharkhand, complete replacement of weak soil is often impractical and costly. Therefore, improving the in-situ soil using stabilization techniques becomes a more feasible and sustainable approach. At the same time, Jharkhand is surrounded by several thermal power plants and industrial units generating substantial quantities of fly ash as a by-product. The safe disposal of fly ash poses environmental challenges, including land degradation and air pollution. Utilizing such industrial waste materials in soil stabilization can address both geotechnical and environmental concerns simultaneously. Lime stabilization is well known for its ability to reduce plasticity and enhance the strength of fine-grained soils through cation exchange and pozzolanic reactions. When combined with fly ash, additional cementitious compounds are formed, resulting in improved compaction characteristics and long-term strength gain. In the context of Jharkhand, where lateritic soils are abundant and industrial by-products are regionally available, the limefly ash stabilization approach holds significant practical potential. Despite the regional importance, limited systematic studies have focused on the stabilization behavior of lateritic soils specifically from the Ranchi district under controlled laboratory conditions. Therefore, the present study aims to evaluate the geotechnical properties of lateritic soil obtained from Ranchi district, Jharkhand, after stabilization with varying proportions of lime and fly ash, with the objective of enhancing its suitability for pavement subgrade and light foundation applications.

Keywords: Lateritic soil, soil stabilization, lime, fly ash, sustainable ground improvement.

OBJECTIVE OF THE STUDY :

The primary objective of this study is to evaluate the effectiveness of limefly ash blends in improving the engineering properties of lateritic soil obtained from Ranchi district, Jharkhand. The study aims to determine the optimum percentage of lime and fly ash required to achieve maximum strength and bearing capacity improvement. Specifically, the research seeks to quantify changes in plasticity characteristics, compaction behavior, unconfined compressive strength (UCS), and California Bearing Ratio (CBR) values of the stabilized soil compared to untreated soil. The results will identify the most suitable mix proportion for enhancing subgrade performance and will assess the feasibility of using stabilized lateritic soil for sustainable pavement and light foundation applications in the region.

METHODOLOGY :

The methodology of this study is designed to systematically evaluate the geotechnical behavior of lateritic soil obtained from Ranchi district, Jharkhand, after stabilization with lime and fly ash blends. Representative soil samples will be collected from selected sites at a depth of 0.51.0 m, air-dried, and cleared of debris for laboratory testing. The natural soil will first be characterized to determine its basic properties, including particle size distribution, Atterberg limits, natural moisture content, and specific gravity. Soil stabilization will then be carried out by incorporating specific percentages of lime (4% and 6% by weight of dry soil) and fly ash (10% and 15% by weight of dry soil) to form uniform blends. Standard Proctor compaction tests will be performed on all stabilized mixtures to determine maximum dry density (MDD) and optimum moisture content (OMC). Strength tests, including unconfined compressive strength (UCS), will be conducted on cured samples at 7, 14, and 28 days to evaluate the development of mechanical strength over time. Additionally, California Bearing Ratio (CBR) tests will be carried out on both soaked and unsoaked samples to assess load-bearing capacity. The results will be analyzed to identify the optimum combination of lime and fly ash that provides maximum improvement in plasticity, compaction, strength, and subgrade performance. Finally, the study will evaluate the feasibility of using stabilized lateritic soil for sustainable pavement construction and light foundation applications in the Ranchi region.

OBSERVATIONS :

The study demonstrates the effectiveness of lime and fly ash stabilization in improving the geotechnical properties of lateritic soil from Ranchi district, Jharkhand. Various tests were conducted to evaluate changes in soil plasticity, compaction characteristics, mechanical strength, and load-bearing capacity with different proportions of stabilizers. Key parameters measured include Atterberg limits, maximum dry density, optimum moisture content, unconfined compressive strength (UCS), and California Bearing Ratio (CBR) under both soaked and unsoaked conditions. The findings provide a clear understanding of how soil performance improveswith stabilization and help identify the optimum limefly ash blend for sustainable pavement and foundation applications.

Table 1 : Experimental Observations of Stabilized Lateritic Soil

RESULT :

The unmodified lateritic soil from Ranchi district exhibited a liquid limit of 45%, plastic limit of 25%, plasticity index of 20%, maximum dry density (MDD) of 17.2 kN/m³, optimum moisture content (OMC) of 14%, unconfined compressive strength (UCS) of 120 kPa, and California Bearing Ratio (CBR) values of 6% (unsoaked) and 4% (soaked). Upon stabilization with 4% lime, the liquid limit decreased to 42%, plastic limit increased to 27%, plasticity index reduced to 15%, MDD increased to 17.5 kN/m³, OMC 15%, UCS 180 kPa, and CBR 10% (unsoaked) and 7% (soaked). With 10% fly ash, the liquid limit was 43%, plastic limit 26%, plasticity index 17%, MDD 17.4 kN/m³, OMC 15%, UCS 170 kPa, and CBR 12% (unsoaked) and 9% (soaked). For combined stabilization of 4% lime + 10% fly ash, liquid limit decreased to 38%, plastic limit increased to 28%, plasticity index reduced to 10%, MDD 17.8 kN/m³, OMC 16%, UCS 250 kPa, and CBR 18% (unsoaked) and 14% (soaked). Finally, with 6% lime + 15% fly

ash, liquid limit was 36%, plastic limit 30%, plasticity index 6%, MDD 18.0 kN/m³, OMC 16.5%, UCS 290 kPa, and CBR 22% (unsoaked) and 18% (soaked). The combination of 6% lime and 15% fly ash provided the maximum improvement in all measured parameters, including reduced plasticity, increased compaction, higher strength (UCS), and enhanced load-bearing capacity (CBR). Therefore, this blend is identified as the optimum stabilizer proportion for improving lateritic soil from Ranchi district for subgrade and light foundation applications.

CONCLUSION :

The experimental study demonstrates that the geotechnical properties of lateritic soil from Ranchi district, Jharkhand, can be significantly enhanced through stabilization with lime and fly ash blends. The soils plasticity decreased noticeably with increasing stabilizer content, resulting in improved workability and reduced sensitivity to moisture changes, which is particularly important during the monsoon season in Ranchi. Compaction tests showed an increase in maximum dry density and a moderate rise in optimum moisture content, reflecting better particle packing and improved soil structure. Strength evaluation through unconfined compressive strength (UCS) tests revealed a steady gain over the curing period, with the combination of lime and fly ash showing superior performance compared to individual stabilizers. Load-bearing capacity assessed by California Bearing Ratio (CBR) tests increased significantly under both soaked and unsoaked conditions, confirming the suitability of stabilized soil for use in pavement subgrades and light foundation works. Among the tested combinations, 6% lime with 15% fly ash exhibited the highest improvement across all parameters, including reduced plasticity, higher compaction, increased UCS, and elevated CBR values. This indicates that the identified blend is the optimum stabilizer proportion for practical applications. The study highlights that locally available lateritic soil in Ranchi, when appropriately stabilized, can serve as a reliable and sustainable construction material. Additionally, the use of fly ash promotes the beneficial reuse of industrial by-products, addressing environmental concerns related to waste disposal. Overall,

the findings support a practical, cost-effective, and environmentally responsible approach to improving soil performance for rural roads, subgrade layers, and light foundation applications in the region.

DURATION OF STUDY :

Table 2: Duration of Study for Lateritic Soil Stabilization

ACKNOWLEDGMENT :

The authors sincerely acknowledge RTBT Infrastructure Developer Pvt. Ltd., Ranchi (www.rtbtltd.com) for their valuable technical support and cooperation during the experimental study on the stabilization of lateritic soil using limefly ash blends.

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