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About this book

This book comprises select proceedings of the annual conference of the Indian Geotechnical Society. The conference brings together research and case histories on various aspects of geotechnical and geoenvironmental engineering. The book presents papers on geotechnical applications and case histories, covering topics such as (i) Characterization of Geomaterials and Physical Modelling; (ii) Foundations and Deep Excavations; (iii) Soil Stabilization and Ground Improvement; (iv) Geoenvironmental Engineering and Waste Material Utilization; (v) Soil Dynamics and Earthquake Geotechnical Engineering; (vi) Earth Retaining Structures, Dams and Embankments; (vii) Slope Stability and Landslides; (viii) Transportation Geotechnics; (ix) Geosynthetics Applications; (x) Computational, Analytical and Numerical Modelling; (xi) Rock Engineering, Tunnelling and Underground Constructions; (xii) Forensic Geotechnical Engineering and Case Studies; and (xiii) Others Topics: Behaviour of Unsaturated Soils, Offshore and Marine Geotechnics, Remote Sensing and GIS, Field Investigations, Instrumentation and Monitoring, Retrofitting of Geotechnical Structures, Reliability in Geotechnical Engineering, Geotechnical Education, Codes and Standards, and other relevant topics. The contents of this book are of interest to researchers and practicing engineers alike.

Table of Contents

Frontmatter

Behaviour of Square Footing on Cement Modified Fibre Reinforced Sand Layer Underlain by Soft Clayey Soil

Deep foundations are generally suggested when soil at the site is weak soft clayey soil. The cost of construction of deep foundations like piles and piers is generally very expensive. However, bearing capacity of weak foundation soil can be improved by various soil stabilization methods so that it becomes suitable for shallow foundation. In present investigation, a layer of sand modified with 5% cement and reinforced with 0.75% polypropylene fibre was placed on top of soft clayey soil. Optimum percentage of cement and fibre required was first determined from proctor compaction tests and direct shear tests. Three different percentages of cement as 2, 3.5 and 5% and four different percentages of fibre as 0.25, 0.5, 0.75 and 1% were used for the study. Laboratory modelling was carried out on steel tank with square concrete block of size 20 cm × 20 cm and thickness 4 cm used as footing. Loads were applied by hydraulic jack and recorded in proving ring. Two dial gauges were used in diagonally opposite direction to measure settlement. Load-settlement behaviour of footing was studied by varying the ratio of thickness of top sand layer (H) to the width of footing (B) (as H/B = 0, 0.5, 1, 1.5 and 2) for both unreinforced and cement modified fibre reinforced sand layer underlain by soft clay. Optimum H/B ratio for cement modified fibre reinforced sand layer was found to be 1. However, for unreinforced sand layer, the H/B ratio was found to be significantly higher.

Banchiva K. Marak, Nirmali Borthakur

Enhancing Properties of Black Cotton Soil Using Bacterial Culture

Black cotton soil is considered as most traitorous soil because of is high swelling and shrinking properties and extremely low bearing capacity. Pavements or structures constructed directly on black cotton soil without any treatment may lead to failure of the structure. Many stabilization techniques like use of fiber, geotextiles, fly Ash, rice husk ash, plastic waste, etc., have already been successfully used to stabilize such soils. In this work, an attempt has been made to stabilize and improve the engineering properties of black cotton soil of Surat zone using bacterial culture technique. Many bacteria have been found to precipitate calcium carbonate, which is a cementetious material, increases the strength of clayey soils by altering their properties.

Ratna Jadvani, Nilesh Savani

Comparative Study of Subgrade Strength of Soil Using Bio-Enzyme

Environmental concerns have significantly influenced the construction industry regarding the identification and use of environmentally sustainable construction materials. Bio-Enzymes (organic materials) have been introduced recently for ground improvement projects such as pavements and embankments. The present experimental study was carried out in order to evaluate the subgrade strength of two different clayey soil treated with two different types of enzymes, namely TerraZyme and EarthZyme, as assessed through California bearing ratio (CBR) test and standard Proctor test. Soil specimens to be tested are prepared using different dosages of Bio-Enzyme (1, 2, 3 and 4 ml) mixed with water at optimum moisture content, and then it is sprayed over soil and compacted. Bio-Enzyme reduces the voids between the particles of soil and minimizes the amount of absorbed water in the soil so that the compaction caused by the enzymes can be maximized. It is seen that with the addition of Bio-Enzyme, OMC first decreases and then increases while MDD increases and then decreases. In case of CBR test, CBR value increases and then decreases.

Wafa Yousef, Soumya Jose

Determination of Shear Strength, Shear Viscosity and Liquidity Index Using Fall Cone Penetrometer

In the usual case, the fall cone test has been used to estimate the undrained shear strength of insensitive remoulded clays. Its concept was based on the critical state soil mechanics and is well established. It is only recently that the use of this simple laboratory equipment has been extended to estimate the shear viscosity of soils which are well below their liquid limit. At these water contents, the viscous strength helps to understand the resistance of soils to flow in penetration tests, pile driving and landslides. This paper reports the results of fall cone tests under different loads. In this study, the effect of water content on shear viscosity was investigated by varying the weight of the cone. All the tests were conducted using speswhite kaolin clay. The samples were thoroughly mixed with water and then kept overnight in air-tight containers to ensure proper mixing of the clay with water. The fall cone apparatus was modified to accommodate an LVDT connected to a high-speed data logger which enabled the cone penetration to be logged at every 0.01 s. The mass of the standard cone was increased by 390 to over 1000 g with the use of stainless steel discs. In some tests, the cone was not permitted to fall freely but was driven at a constant rate of 1.25 mm/min. The load versus penetration resistance measured at different water contents showed that the penetration increased with the increase in LI and at a given load, the results were consistent with the triaxial test results. Shear viscosity was calculated using the rate at which the cone penetrated into the soil and was shown to decrease with the increase in LI. Design curves were obtained for the different weight of the cone which can be implemented in the selection of soil characteristics, for example, in estimating the capacity of different driven piles.

Jiji Krishnan, Ashish Juneja, C. H. Solanki

Cost-Effective Foundation System for Medium Rise Residential Building on Typical Soft Kolkata Soil

In present scenario due to rapid growth in population, it is not possible to construct each and every residential building on hard soil. Some time, it is necessary to construct building on soft soil. One of the examples is Newtown, Rajarhat, Kolkata. Rajarhat is a developing area in Kolkata where most of the residential buildings are medium rise, i.e. four or five storied. In that area, soil consists of very soft clay having very low value of SPT value (2–5) up to a depth of 12 m or below, followed by hard strata. In most of the cases, shallow foundation cannot give feasible solution and structural designers prefer pile foundation before adopting other alternatives techniques to improve the soil. Pile foundations are not very cost effective. Cost of the foundation constitutes a significant part of the total cost of the structure. Hence, reduction in cost of the foundation leads to reduction in total cost of the structure. In this study, an effort has been made to recommend feasible cost-effective foundation system by using ground improvement technique (by using stone column) vis-vis pile foundation. A typical medium rise building (G + 4) has been chosen on a typical soft soil profile, typical to Rajarhat area. A comparative study has been made to suggest cost-effective foundation system for medium rise residential building in that area.

Monojit Mondal, Shuvra Saha, J. J. Mandal

Strength and Compaction Behavior of Randomly Distributed Polypropylene Fiber-Reinforced Expansive Clay

Experimental investigations were conducted to study the effects of randomly distributed polypropylene (PP) fiber inclusions on the mechanical behavior of expansive soil. Reinforced soil specimens were prepared at four different fiber contents (0.05, 0.1, 0.15 and 0.2%), and the aspect ratio of fibers (L/D) was kept as 250. A series of compaction tests, unconfined compressive strength (UCS) and split tensile strength (STS) tests were performed on the unreinforced and fiber-reinforced soil specimens. The results proved that the UCS and STS values increased to a greater extent with the inclusion of fibers to the expansive soil. The inclusion of monofilament-type PP fibers within expansive soil contributes to increase the peak axial stress, improve the residual strength and increase the modulus of elasticity, toughness and ductility of the soil. It was noticed that the effect of polypropylene fiber inclusion on the compaction parameters was not much significant (less than 5% variation) due to lightweight and less water absorption capacity of PP fibers. The highest UCS values were obtained with 0.15% fiber content with 12 mm length of fibers for that UCS values increased up to 51% of that of the unreinforced soil. Similar behavior was also observed for STS of soil–fiber mixtures with a gain of 59% in tensile strength. From the UCS and STS test results, some other parameters like secant modulus, shear modulus, resilient modulus and deformability index were also reported for both unreinforced and reinforced specimens. It was seen that secant modulus of expansive soil increased up to 89% and resilient modulus was increased up to 17% on addition of 0.15% fibers. Similarly, other parameters were also improved with the inclusion of PP fibers within the expansive soil.

Brijesh K. Agarwal, Shyam A. Hathiwala, C. H. Solanki

Stabilization of Black Cotton Soil Using Calcium Carbide Residue

A wide variety of soils are available in the world out of which some are good in views of construction engineers and few are problematic due to their swelling and shrinkage properties, and black cotton soil (BCS) is one of them. These properties can easily produce uplift movement and may lift the lightweight civil engineering structures and causing collapse, cracking and ultimately hazard to mankind. In such a case, there is an extreme need for soil stabilization and hence to find and introduce cheap and easily adoptable stabilizing agent. Calcium carbide residue (CCR) which is a by-product of acetylene gas manufacturing industry due to its alkaline properties can be effectively used as stabilizing material, and reducing the environmental problem of its disposal is taken into the frame. This study depicts the use of CCR in stabilizing BCS. Introducing CCR in BCS can increase the strength and swell property of soil, for this CCR fixation point was determined by sequentially adding 1–10% CCR to BCS and studying properties like pH and consistency limits. Strength and swell pressure of BCS were checked with varying percentage of CCR. To study strength properties, unconfined compression test is conducted, and to examine swell properties a portable and in-house fabricated swell pressure measuring device was used. Maximum strength development in stabilized clay is found at 7% CCR cured for 28 days at standard temperature. It was further observed that addition of CCR to BCS resulted in increased strength of about 5 times than that of virgin BCS and it was observed that stabilization of soil with 7% CCR reduces its swell pressure by around 88%.

Mahesh Endait, Suyash Wagh, Shubham Kolhe

Influence of Curing Stress and Curing Time on Unconfined Compressive Strength Behaviour of Cemented Clay

In recent ground improvement techniques to strengthen the weak soils in order to increase the strength characteristics and stiffness of different types of soils, cement stabilisation has shown to be very effective. In cement stabilisation, curing stress and curing time are two important factors. Since previous researchers have mainly focused on importance of the curing time, the present study emphasises on the combined effect of curing stress and curing time. The aim of present study is to examine the effect of curing time on unconfined compressive strength (UCS) of virgin clayey soil treated with cement under predefined curing stress of 5 kPa. Laboratory test including Atterberg limits, light weight compaction test and UCS test were conducted. The UCS tests were performed on clayey soil (CH) with the different percentages of cement (i.e. 8, 10 and 12%) for the curing period of 0, 3, 7, 14, 28 and 56 days. The curing stress of 5 kPa is being applied along with curing time to check the combined effect of both curing time and curing stress. The results show that the curing time and the curing stress have a significant effect on UCS. The UCS value increases with increasing cement content from 8 to 10% but decreases for further increment in cement content (i.e. from 10 to 12%). The 10% cement content is found to be the optimum. UCS values increases with curing stress and having around 10–15% high value compared to the curing time condition. The increase in UCS is attributed due to the reduced pore spaces and increased confinement due to the curing stress. This study concluded that applying curing stress leads to have incremental impact on the strength of soil and being very helpful for attaining higher strengths in early days.

Deepak K. Haritwal, Brijesh K. Agarwal, Anand V. Reddy, Shailendra Kumar

Experimental Study on Load-Settlement Behavior of Circular Plate Supported on Small Diameter Timber Piles Under Vertical Loading

Locally available wooden piles have been traditionally used in this region for improvement of bearing capacity through decades. Use of reinforced concrete pile is quite effective in improving bearing capacity, but there are sometimes disagreements between efficiency, cost effectiveness, sustainability, etc. Experimental study has been done on model footing (circular plate) supported on small diameter timber piles. Both single and groups of piles of variable length with variable spacing have been tested. Timber piles of 3 (three) different length to diameter ratio with different spacing have been used. The study is conducted on test tank constructed with steel plates and filled with zone-II sand. Load test was carried out on a model circular footing of 0.225 m diameter resting on sand with and without timber piles. The piles were installed in sand bed of 3 (three) different relative densities and subjected to vertical loading. Group efficiencies of pile groups were determined for three length to diameter ratio of 20, 25, and 30 with spacing of 2D, 3D, 4D, and 5D. The diameter of piles were taken as 15 mm. Length to diameter ratio, relative density, and spacing between the piles are found to be major factors that influence the performance of the model footing. A regression analysis was done to relate bearing capacity to relative density, spacing of piles, angle of internal friction, unit weight, and length of the pile.

Hitesh Kumar, Nayanmoni Chetia

Stabilization of Expansive Soil Using Terrazyme

The black cotton soil is an expansive soil having a high potential for shrinking and swelling with seasonal moisture variations due to which black cotton soil fails to bear imposed load. Thus, stabilization of black cotton soil is one of the challenging tasks for engineers. The stabilizers used must be economical, easy to implement, and eco-friendly but the methods used conventionally were time-consuming and uneconomical. It is better to use terrazyme to stabilize a soil as it is natural, non-toxic, inflammable, non-corrosive, biodegradable liquid enzyme formulated from fermented vegetable extracts and it shows a permanent effect. This paper deals with a series of tests conducted on virgin soil as well as the tests conducted on the terrazyme treated soil with different dosages such as 0.5/075/1/1.5 cubic meters of soil per 200 ml terrazyme. Adding terrazyme shows significant improvement in engineering properties of soil such as specific gravity, consistency limits, optimum moisture content, maximum dry density, unconfined compressive strength, swelling index, and California Bearing Ratio (CBR) (soaked). On the basis of these results, the optimum dosage is obtained. Apart from this, the soil which we are used must have at least 10% of clay content for the effect of terrazyme.

Abhishek Tiwari, J. K. Sharma, V. Garg

Stabilization of Expansive Black Cotton Soil Using Alkali-Activated Binder with Glass and Polypropylene Fiber

Expansive soil exhibits high swelling and shrinkage behavior when moisture fluctuation occurs; this volumetric variation in black cotton soil (BCS) renders unsuitable for use in geotechnical applications. The present paper emphasizes an experimental investigation on the effect of discrete polypropylene (PP) and glass fiber (GF) with alkali-activated binder (AAB) on geomechanical properties of BCS. Hence, the present study aims to compare the geoengineering and microstructural characteristics between PP and glass fiber on AAB treated BCS. PP and GF were varied from 0 to 0.4% with 5% AAB in the BCS. AAB is produced by the reaction between alkali-activator solution (sodium hydroxide and sodium silicate) and aluminosilicate precursor (Class-F fly ash/slag). Microstructural analysis for AAB treated BCS reinforced with both PP and GF is performed through a stereomicroscope, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). The unconfined compressive strength (UCS), indirect tensile strength (ITS) California Bearing Ratio (CBR) and linear shrinkage tests for glass fiber-AAB and PP fiber-AAB treated BCS are carried out. The influences of varying percentages of different fiber with AAB content in the BCS show a significant improvement in geoengineering properties, especially tensile strength. It is observed that the addition of 5% AAB with 0.3% of glass fiber and PP fiber reduces the linear shrinkage by 12–15% while CBR and ITS values are increased by 20–30%. From the results, it is observed that the PP fiber-AAB treated BCS achieves maximum mechanical strength when compared to glass fiber-AAB treated BCS.

Mazhar Syed, Sagar Agarwal, Anasua GuhaRay

Strength Enhancement of Clayey Soil Using Cement Kiln Dust and Recron Fiber

Due to the fast growth of economy, construction work is very rapid in India. The removal of poor layer of ground is uneconomical. Scarcity of land forces to search new material so that bearing capacity of poor ground can be improved. Therefore, alternative method is used for the stabilization of soil. Cement kiln dust (CKD) is a waste material obtained from the cement industries. This paper presents the stabilization soil having low bearing capacity by mixing CKD and Recron fiber. CKD has pozzolanic capacities which may improve the engineering behavior of clayey soil. An experimental study was carried out by mixing CKD with soil in the ratio of 96:04, 92:08, 88:12, 84:16, and 80:20. It is found that the un-soaked California bearing ratio (CBR) increases from 6.7 to 12%. The Recron fiber also improves the soil properties of loose soil due to the reinforcing action. The inclusion of fibers in the optimum mixture of soil and CKD is in the ratio of 0.1, 0.2, 0.4, and 0.8% by weight of mixture. The CBR value increases maximum for 0.4% of Recron fiber from 12.35 to 15.67%. The stabilized soil may be used as subgrade for construction of road.

Amrendra Kumar, Sunita Kumari, Ravi Kumar Sharma

Effect of Rice Husk Ash on the Behaviour of Highly Compressible Clay

This study explores the possibility of using rice husk ash blends for soil improvement. The results of the study show that rice husk ash renders the soil less plastic. The liquid limit, plasticity index and flow index of the rice husk ash–clay blends show a significant decrease with the increase in ash content. The compaction curves tend to shift to the right. The optimum moisture content increases, and dry density decreases with the increase in ash content. The addition of rice husk ash not only increases the unconfined compressive strength of the clay soil but also the post peak strength of the blends. An increase of approximately 100% is observed at 5% ash addition. The California bearing ratio (CBR) of the clay–rice husk ash blend is 37% more than the untreated soil. The results of the investigation emphasize the benefit of rice husk ash replacement with in-situ soil for improving the geotechnical properties.

E. R. Sujatha, M. Abijayan, M. Vignesh, V. Shriram

Geotechnical Properties of Lime Treated Soil Contaminated with Sulphatic Water

Chemical stabilization using calcium-based stabilizers such as lime and cement to improve the properties of soils is well-known technique since previous several decades. However, the longevity potential of calcium-based stabilized soils with change in environmental conditions, particularly, in migration of contaminated sulphatic water is a matter of concern for the geotechnical engineer. The gypsum (Ca2SO4.2H2O) is main source of sulphate and is abundantly available in soils throughout the world, despite of its low solubility rate. The present work is aimed to study the potential of lime stabilized soil contaminated with migration of sulphatic water. Detail experimental works to determine the plasticity, compaction characteristics and one dimensional oedometer swell percentage have been performed in expansive soil alone/and stabilized with optimum lime content with water having sulphate concentrations of 0, 3000, 5000, 10,000 and 20,000 ppm. The result shows that the plasticity of expansive soil contaminated with sulphatic water reduces drastically with lime treatment. Further, Optimum Water Content (OWC) of soil is observed to be less than lime treated soil contaminated with various concentration of sulphatic water, whereas maximum dry density (MDD) of sulphate contaminated soil reduces with lime treatment. It is interesting to observe that lime treated soil exhibits drastic swell after inundating with sulphatic water having different concentration. The formation of highly expansive ettringite mineral by ionic reaction between calcium-aluminium-sulphate in the presence of water results the swell in lime treated soil.

Shivanshi, Vijay Bahadur Singh, Arvind Kumar Jha

Geotechnical Properties of β-Glucan Treated High Swelling Clay

Soil stabilization refers to enhancing the properties of a soil for engineering purposes. A holistic approach in selection of materials for soil stabilization is required since certain materials may cause environmental problems such as pollution during manufacturing, interaction with ground water table, soil nutrients, etc. β-glucan, a biopolymer offers a novel alternative and has greater potential for application in soil stabilization, yet only limited research is available. β-glucans are linear homopolysaccharides composed of D-glucopyranosyl residues linked via a mixture of β-(1–3) and β-(1–4) linkages. β-glucan has good tensile strength along with good bonding and adsorption characteristics. In addition to structural orientation, molecular weight plays a role in stabilization owing to gel forming potential. Polysaccharides have the tendency to form a film coating. β-glucan was added in quantities of 0.5, 1, 1.5, 2, 2.5, and 3% to high swelling clay soil. Index and select engineering properties of the treated soil were determined. Rheological properties such as pH and viscosity were also studied. Durability tests, tests on biopolymers such as gel matrix formation and its degradation were conducted. The test specimens were prepared for 0, 7, 14, 28, and 56 days to study the impact and variation of shear strength on treated soils. Scanning electron microscopy images revealed the bonding of β-glucan and soil. The treated soils have shown improvement in engineering properties.

M. Vishweshwaran, S. T. Soundarya, E. R. Sujatha

Effect of Various Parameters on Electrokinetic Dewatering of Saturated Clay

Electrokinetic dewatering is an effective method to remove water from saturated clay having low hydraulic conductivity. This performs better than other dewatering methods like sand drains, prefabricated vertical drains, vacuum dewatering, etc. In electrokinetic dewatering, low intensity direct current is applied across the soil layer through electrodes, thereby accelerating the flow due to changes in physio-chemical processes. In the present study, a series of laboratory experiments were performed on saturated clay collected from Lunawada region of Gujarat to study the effect of various parameters on electrokinetic dewatering. A water tight wooden box (40 cm × 40 cm × 30 cm) was used to perform the experiments. Hollow circular stainless steel tubes (length = 25 cm and inner diameter = 1.9 cm) were used as electrodes. Perforations with diameter of 5 mm were provided on electrodes at regular intervals to allow and collect water from surroundings during the experiments. Efficiency of electrokinetic dewatering was studied under variations of voltage, electrode spacing and pH. Water collected at cathode was removed manually from top at cathode, and the quantity was measured. The results confirm that dewatering efficiency increases with an increase in voltage as water flows under greater electric gradient at higher potential difference. The decrease in centre to centre spacing between anode and cathode causes overlapping of electric field which enhances dewatering efficiency. Decrease in pH of soil causes soil to be more acidic in nature that results in less dewatering efficiency. Further, cracking patterns near anode for each series of experiments was also studied to enhance the understanding of electrokinetic dewatering. It is confirmed from the experiments that electrokinetic dewatering is greatly influenced by voltage, electrode and pH. Other parameters like electrode pattern, type of soil, type of electrodes, etc., can also be evaluated for better understanding of electrokinetic dewatering.

Veerabhadrappa M. Rotte, Abhishek A. Sutar, Aayushkumar Patel, Anish Patel

Plasticity and Swelling Characteristics of Geopolymer Treated Expansive Soil

Expansive soil causes extensive damage to geotechnical structures owing to its high volume instability. Cement and lime are the most commonly used material to improve these soils by reducing its plasticity, swelling characteristics and increasing strength. However, the production process of these traditional stabilisers is energy intensive and it also serves as a major source of green-house gas emission leading to severe problems like global warming. Geopolymer is a new generation alternative binding material for conventional cement. This is primarily produced from industrial wastes like slag or fly-ash which are rich in alumino-silicates. When activated with alkalis, these products form geopolymers, which provides high strength to soil and have low cost, low energy consumption and is eco-friendly. This study explores the efficiencies of ground granulated blast furnace slag (GGBS)-based geopolymer binder in improving the properties of expansive soil in comparison to cement and lime. In this study, the expansive soil is mixed with 0, 5, 10, 15 and 20% of GGBS and activated with sodium hydroxide solutions of 0.5, 1, 2 and 4 M concentrations. However, cement and lime are mixed with the soil in the proportions of 1, 2, 4, 8, 12 and 15% by weight of the soil. The consistency limits and swelling characteristics of geopolymer, lime and cement treated soils are evaluated at 0, 3, 7 and 30 days of curing. It is found that the plasticity characteristics are improved and swelling and shrinkage of the expansive soil is greatly reduced with increasing concentration of these admixtures. Curing period also influences these properties. It is also observed that the performance of geopolymer is comparable to that of cement and lime. So, geopolymer can be effectively used as an alternative stabilising agent to modify the plasticity and swelling properties of expansive soil.

Manaswini Mishra, Prabodha Kumar Sahoo, Suresh Prasad Singh

Improvement in Soil Subgrade Using Natural Fibre (Kenaf and Coir Fibre)

India has one of the largest road networks in the world. Around 20% land area of India is covered with soils having low California bearing ratio (CBR) and shear strength values. Pavements laid over such type of soil lead to continuous deformation as a result of which cracks are developed. It increases the maintenance cost and disrupts traffic services. From past decades, various researchers have tried to overcome such type of problems either by using traditional techniques like lime, cement, mechanical stabilization or by using modern techniques like geosynthetics or natural fibres, etc. The present paper deals with the use of natural fibres (kenaf and coir) as a reinforcing material to assess the improvement in strength characteristics of unreinforced soil. The soaked CBR and maximum dry density (MDD) of virgin soil were 2.11% and 1.823 gm/cc, respectively. Kenaf and coir fibre were cut in length of 15 mm and randomly mixed with the unreinforced soil in different percentages (i.e., 0.25, 0.50, 0.75, 1.0, 1.25 and 1.5%) by weight of dry soil. The results obtained indicate that MDD value decreases with increase in fibre content with maximum value of 2.01 g/cc at 0.25% fibre content. The soaked CBR value increases up to 1% fibre content and then decreases. Increase in CBR value indicates that the bearing capacity of mixture (soil + fibre) increased due to the three-dimensional bonding between them. It can be concluded that natural fibres like coir and kenaf can be effectively used as soil reinforcement material.

Shalinee Shukla, Ayush Mittal, Sunit Kumar

Stabilization of Sediment Soil by Alccofine and Geogrid

The main objective of this work is to study the engineering characteristics of sediment soil. The sediment soil is having poor CBR value and is porous and loamy in nature. This property of sediment soil poses problems worldwide that serves as challenge to overcome, for the geotechnical engineers. The aim of this project is to stabilize the sediment soil using different percentages of the stabilizer, i.e., Alccofine 1108SR, and to check for which percentage of the stabilizer added will be the maximum strength gained with the aid of geogrid (biaxial-type geogrid) as reinforcement and also to improve the overall engineering properties of the sediment soil. The results will be then compared with the standard ratio of soil without any stabilizing agent and reinforcement.

Shimna Manoharan, C. Shashinaga, U. Pradeepa, P. R. Pavana Kumara

A Novel Method to Improve the Durability of Lime-Treated Expansive Soil

Pavements often suffer from different distresses such as rutting and cracking due to the presence of underlying expansive subgrade soils. The ingress and egress of water have a detrimental effect on the performance of the pavements due to the swell-shrinkage behaviour of the subgrade soil. Millions of dollars are invested annually for the maintenance and rehabilitation of such pavements. Traditionally, lime has been used for treating problematic subgrade soils to enhance the strength, stiffness and other engineering properties. However, previous studies have shown that lime-treated soils often incur a significant strength loss when exposed to moisture intrusion, especially in the early curing periods. This research work explores the possibility of using a novel silica-based admixture to enhance the engineering properties of lime-treated soil, reduce the swelling potential and deter the moisture-induced strength loss incurred during early curing periods. Laboratory test results suggest that an expansive soil treated with lime and silica-based admixture has a significant reduction in water absorbing potential and strength loss during the early stages of curing as compared to the soil treated with lime only.

Nripojyoti Biswas, Sayantan Chakraborty, Anand J. Puppala, Aritra Banerjee

Strengthening of Cohesionless Soil Using Basalt Fibre Geogrids

Modern soil reinforcement uses more durable materials and advanced methodology in increasing the bearing capacity of feeble soils [2]. Basalt fibre geogrids can be characterized as a green nonpolluting material used in stabilizing the week foundation soils by the interaction of frictional forces that develops at the soil reinforcement interface [3]. This revolutionary fibre obtained from volcanic extrusive basalt rock possess high tensile strength than steel fibres and even effectively replaces glass and carbon fibres in terms of cost-efficiency and performance [7]. Tests were carried out to determine the effectiveness of basalt fibre geogrids in cohesionless soil. Cellular arrangement [8] of geogrid with coir fibre inclusions at different confinement depth ratios [1] (CD/B = 0.25, 0.75, 1.5 and 2) and variation in the number of geogrid cells (N = 1, 5 and 9) were performed. Results show that maximum strength can be attained within the zone of influence at optimum coir fibre content [6].

J. Jasmin, K. Balan

Stabilisation of Kuttanad Soil Using Calcium and Sodium Lignin Compounds

Kuttanad region in Kerala is the lowest lying area in India with an elevation of one metre above mean sea level. Soil in this region is characterised by low bearing capacity, hence, construction works on Kuttanad soil is often problematic and expensive. Traditionally, stabilisation in Kuttanad soil is done by hydrated lime, Portland cement, fly ash, etc. Stabilisation of weak soil with industrial by-products is commonly adopted nowadays because of its economical as well as environmental benefits. One such material is lignin; chemically called as lignosulphonates produced as a by-product in paper pulping industry. Lignin compounds are available in different chemical compositions based on the cellulose separator used during pulping process. This paper presents in detail the effectiveness of stabilising Kuttanad soil using sodium as well as calcium forms of lignin. The effect of lignin on compaction characteristics, consistency limits, unconfined compressive strength and CBR were studied using a series of laboratory tests and the optimum percentage of additive was found out. A comparative study has also been done with the two compounds to identify which one has the best stabilisation capacity.

B. S. Sabitha, Y. Sheela Evangeline

Efficacy of Almond Shell Ash Inclusion on the Geotechnical Behavior of Lime Blended Kaolinitic Soil

The current study focuses on studying the effect of almond shell ash (ASA) inclusion along with lime in addressing issues related to strength and volume change behavior of a typical problematic soil. Experiments were carried out on both natural as well as amended soil mixtures having varying percentages of lime and ASA (added based on dry weight of soil). The addition of ASA reduced the plasticity characteristics of selected kaolinite rich clay. Of all the mixtures, the mixture containing 1% ASA and 0.5% lime exhibited maximum optimum moisture content (OMC) and lowest value of maximum dry density (MDD). Upon curing to 28 days, the same mixture exhibited the unconfined compression strength (UCS) value 76 kN/m2. The results pertaining to UCS values indicated that the rate of gain of strength increased proportionally up to 1% ASA addition, followed by which there was a consistent decrease in the rate of gain of strength even in the presence of lime and is attributed to pore saturation with ASA. The addition of lime aids in better binding between non-plastic ASA particles and kaolinite-rich clay which was confirmed by scanning electron microscopic (SEM) images and X-ray diffraction (XRD) studies. SEM images confirmed the presence of agglomerated particles with homogenous mass exhibiting reduced pore opening size for mixture containing both ASA and lime.

K. Venkata Vydehi, Arif Ali Baig Moghal, Syed Abu Sayeed Mohammed, Mohammed Abdul Lateef, Mubarak Ali, Aqsa Basheer, Adil Ahmad Handoo, Syed Zahid Nabi, Burhan Ul Wafa

Comparative Study of Strength Characteristics of Clayey Soil Mixed with Natural and Synthetic Fibers

Soil reinforcement is nowadays an important method of improving ground by enhancing the properties of the in situ soil. Sometimes, soils available near the construction site is not strong and improving such soils will be beneficial for the project. Reinforcing such soils either by synthetic or natural fiber is a technique to improve the strength of such soils (Maity et al. in Proceedings of Indian geotechnical conference, Delhi, pp 285–288 (2012) [2]). However, each day millions of plastic bags of cement or jute bags of food grains are released to the market and disposal of such bags after use generally forms a part of solid waste requiring disposal. However, such bags can be gainfully used in improving soil properties by random mixing for compaction (Santoni et al. in J Transp Eng 127:96–104 (2001) [1]), thereby causing gainful disposal of such materials and simultaneously improving soil properties at a low cost. In view of large scale infrastructure development and wide spread rural road construction in India, such use may be very welcome. Aiming this an experimental program of testing local fine-grained soil, randomly mixed with plastic cement bags and jute bags cut in square shape of varying sizes and mixed with soil in various percentages was made for finding compaction characteristics and California bearing ratio values at optimum moisture content to estimate the improvement of these properties over those of virgin soil. Results of these tests are reported in this paper.

Sanchari Hati, B. C. Chattopadhyay, Joyanta Maity

Optimal Foundation System for a Storage Tank in Liquefiable Soil—A Case Study

Storage tanks are constructed in all refinery complexes for the bulk containment of fluids at different stages of the refinery process. This paper presents the optimal foundation solution for a storage tank located at Bongaigaon, Assam. Subsoil at the present location consists of top 11 m loose to medium dense silty sand which is further underlain by dense sand with fines content less than 15%. The refinery site is located in the highly seismic prone zone and topsoil up to substantial depth is susceptible to liquefaction. In order to construct a storage tank in such type of soil, it is necessary to provide suitable foundation system for controlling liquefaction and to satisfy the performance requirement. Stone column is one of the ground improvement techniques to increase the bearing capacity and to reduce the total and differential settlements. Ground improvement using vibro stone columns is used to mitigate the liquefaction susceptibility and to minimize the differential settlement of tank foundation. The various aspects of subsoil conditions, design, construction methodology, quality control and hydrotest results are discussed in this paper.

Sampat Raj, V. K. Panwar, Sanjoy Bhowmik

Response of Multilayered Stepped Geocell Reinforcement in Soil Structures

The conventional single layer of geocell reinforcement, as a measure of ground improvement technique, has widely been accepted to strengthen weak soil into a competent foundation layer. Since its inception, several researches are performed with such layer configuration and successfully applied in field. The performance factors of geocell systems have been improved with various laboratory/in-house investigations and their critical appraisals on parametric influences. However, it is noticed that most of the reinforcement volume (about one-third of the total with respect to loading size when full load transmission up to the geocell bottom is allowed) remain unused in case of the single-layer geocell system. Besides, compaction of soil at a greater depth of geocell experiences a great deal of difficulties. In addition, the thicker layers undergo considerable buckling at the top of geocell walls (situated just under the load) affecting localized settlement without any appreciated improvement. Therefore, replacing the single layer, with a multilayered stepped configuration, would mitigate this issue with an additional benefit in terms of material optimization. As of now, the mechanism of multilayered structure has not been developed explicitly which thrusts more emphasis on this issue to be addressed. In this study, the performance of multilayered system is envisaged to investigate through numerical simulation in Plaxis2D. In doing so, initially, the work reported in Biswas (2019) is validated to confirm the parametric considerations. Being successful, it has further been used and extended for the present objective. A comparative performance of single with multilayered configuration is presented to confirm the usefulness of the proposed concept.

Haradhan Sarkar, Arghadeep Biswas

An Innovative Foundation Technique for Residential Building—Case Studies

In recent years, rapid development of urban environment demands large number of residential units which are compounded with scarcity of suitable land. This compelled practicing engineers to find an innovative foundation technique to improve the unsuitable land which are technically feasible and economical. This paper presents case histories of similar conditions where ground improvement techniques using vibro stone columns was chosen to support residential buildings in weak soil strata. The foundation challenges such as bearing capacity, total and differential settlements, and mitigation of liquefaction were addressed. Various aspect of subsoil conditions, design aspects, construction methodology, and quality control measures are discussed.

B. Vani, P. V. S. R. Prasad

Vibro Compaction Technique in Liquefaction Mitigation and Its Value Addition—A Case Study

India being a rapidly developing nation requires quality infrastructural developments almost in every field ranging from industries, transportation, education, etc. Hence, the stability of these structures should be least ensured against the geotechnical concerns like bearing capacity, settlement, and liquefaction. The present study is about the development of an institutional campus located in seismically active zone. The proposed development comprises of both academic and residential buildings whose loading intensities ranges from single to maximum of 8 stories proposed to rest on open/pile foundations. The subsoil comprises of loose-to-medium dense sand (fines <12%) revealed that the soil is susceptible to liquefaction. The deep vibro compaction (VC) technique considered to be an effective solution to mitigate the liquefaction and found to be an alternate foundation solution over the conventional piling method. In addition, fully automated real-time quality control measures adopted to ensure the execution of VC works is also discussed.

C. Ramanathan, P. V. S. R. Prasad

Granular Anchor Pile System for Resisting Uplift: A Review

Granular anchor pile (GAP) system is a modified stone column in which the stone column is reinforced using an anchor rod with an anchor plate placed at the bottom. The anchor rod is embedded in the footing of the structure which rests on the stone column. This system prevents the uplift of the structure which may be caused by uplift forces like the presence of expansive soil below the footing, wind forces, or buoyant forces. This paper presents a review about the application of granular anchor piles, the conditions in which it can be used and the method of installation. A discussion on the parameters like length, diameter, soil type, and its strength which influences the uplift capacity of the granular anchor pile is also given.

Jerin Joseph, Shailendra Kumar, J. B. Patel, Yogendra Tandel

Enhancing Strength Properties of Soft Soil Using Carbon Fiber

Civil engineers are always ambitious when it comes to new materials that can face many challenges which have cropped up with time in the world. This paper enquires the effectiveness of carbon fiber (CF) as a better reinforcing agent to augment the engineering characteristics of soil, especially the shear strength, unconfined compressive strength (UCS), and California bearing ratio (CBR) using CI-CH soil. Varying percentage of carbon fiber (0.05%. 0.1%, 0.2%, 0.4%, and 0.6% by weight of soil) were included to analyze the gain in relative strength of soil. The research was conducted to assess the shear parameters, unconfined compressive strength (UCS), and California bearing ratio (CBR) of soil with respect to varying percentage of carbon fiber. The analysis revealed that, 0.4% of carbon fiber in the soil mixture resulted in enhancing the strength properties of the soil to the maximum. The soil reinforced with carbon fiber increased cohesion, internal angle of friction, UCS, both soaked and unsoaked CBR by factor 4.1, 1.78, 1.25, 1.56, and 1.52, respectively.

Swati Sucharita Rout, Rupashree Ragini Sahoo

Settlement Behaviour of Very Soft Soil Reinforced with Stone Columns

Construction on soft soils has always been a problem to geotechnical engineers. A review of the literature reveals that many techniques and methods have been developed to work with such soils. The technique of soft soil improvement by the installation of stone columns has become popular in recent past and has proven its application to many construction situations in soft soils. Construction of stone columns provides a new composite ground consisting of stiff stone column–soil matrix. Stone column reinforcement in the soft ground increases the bearing capacity and improves the settlement characteristics. They can be used to accelerate the rate of consolidation of soft soil deposits through a well-understood mechanism. They act as vertical drains that provide a shorter drainage path for excess pore water pressure to dissipate rapidly. In the present investigation, an attempt has been made to study the settlement characteristics of soft soil reinforced with the stone column. The main objective of the study was to investigate the settlement time behaviour of the stone column in very soft soil having undrained shear strength (cu) ≈ 5 kPa under different bearing pressures and to verify the results of the experimental results with the analytical theory on consolidation rate of composite ground. A compactive effort is applied during the construction of stone column, and its average value is equal to 21.98 kJ/m3. The settlement of the reinforced soft soil bed is reduced by 25.8% when reinforced with stone column diameter of 76.2 mm.

Sareesh Chandrawanshi, Rakesh Kumar

Strength Improvement of Gandhinagar Soil Using Microfine Cement as Grout

Grouting technology is a widely accepted soil improvement technique for improving soil parameters like c and ϕ value. The use of microfine cement grout along with sodium silicate can easily deal with the problems associated with ground improvement, toxicity, and costliness of chemical grouts. Grout is injected under pressure into the material to be grouted until it fills the desired void or until the maximum specified pressure is attained and a specific minimum grout flow is reached. The purpose of this study is to investigate the proper grout mix using microfine cement (whose specific area is greater than the normal cement) and silica used in grouting. An attempt has been made to find the optimum grout mix design at various water content (10 and 20%) and cement content (5, 10, 15, 20, and 25%). The paper discusses about strength improvement of loose sandy soil and silty clay soil. The results shows that with the increase in microfine cement content, the strength of soil will increase, and with the increase in the water content, strength of soil decreases. In this study, direct shear test was performed to find shear strength of loose sandy soil. The grouting properties of microfine grout was found to be better as compared to the conventional grout.

Manank Shah, Manas Kumar Bhoi, Kaushal Vora

Application of Non-woven Polyester Geotextile for Soil Improvement in Pavements

The performance of flexible pavements are greatly affected by the type of subgrade, sub-base, and base course materials; the most important of these are the properties of soil subgrade, as it serves as the foundation for pavement. In India, around 8 lakh km2 area is covered with poor subgrade soil covering central, some parts of southern region, and along the coastline. The pavement constructed over such soils will lead to greater thickness requirement, and it will also fail prematurely under heavy wheel load. In order to overcome such untoward situation, some ground improvement technique has to be adopted. This paper presents the effect of including non-woven polyester geotextile on the strength behavior of weak subgrade soil. The geotextile sheets are placed in single and multiple layers at various depths of soil subgrade and thereby determination of optimum combination and optimum position of reinforcement based on the California bearing ratio results are done. Greater improvement in CBR is observed for soil samples reinforced with geotextile in upper layers of subgrade as compared to lower ones with a maximum increase of 70% corresponding to double layer geotextile at 0.2 and 0.4 H depth from top of mold. It can be concluded that geotextile sheets can be considered as a good earth reinforcement material.

Shalinee Shukla, Ayush Mittal, R. P. Tiwari, Kshma Gupta

Review on Suitability of Rice Husk Ash as Soil Stabilizer

Modern era is an era of sustainable development. Utilizing industrial waste for the development works is an essential principle of sustainable development. Around 70 million hectare area of central India has black cotton soil, so there is a deficiency of stable construction site in these areas. Making these sites suitable for construction activities is a challenging task for geotechnical engineers. India is the second largest rice producer in the world. Around 24 million tons of rice husk and 4.4 million tons of rice husk ash (RHA) are produced annually in India. The effective disposal of such huge quantity is cumbersome, and thus, their use in some other fields must be looked into. The use of RHA as a soil stabilizer not only intensifies the required soil properties but also provides an effective way of its safe disposal. RHA contains rich amount of silica which have capability to replace the exchangeable ions present in clay minerals, thus reducing the shrinkage and swelling behavior of black cotton soil. The present study describes the available knowledge on use of RHA in soil stabilization purposes. The effect of RHA on various index and engineering properties of soil is also discussed based on previous researches in this field.

Ayush Mittal, Shalinee Shukla, Sonu Verma

Analysis of Strength Properties of Lime Stabilized Black Cotton Soil with Phosphogypsum

Expansive soils are those soils which pose a very serious problem when they are subjected to moisture variation. Phosphogypsum is one of the industrial waste by-products that can be utilized for the purpose of soil stabilization. In this study, the strength of lime stabilized soil added with phosphogypsum for immediate 7 and 14 days of curing periods is compared with the strength of phosphogypsum amended black cotton soil for immediate 7 and 14 days of curing. From unconfined compressive strength test, it was found that 6% of phosphogypsum is the optimum content, that imparts the maximum strength to the soil that when it is used alone. The combination of 3% of lime and 6% of phosphogypsum gives the maximum strength, and the strength obtained is relatively higher than the strength of the black cotton soil stabilized with phosphogypsum alone.

H. M. Anusha, Pankaj Bariker, B. Viswanath

Strength Improvement of Sand by State-of-the-Art Microbially Induced Carbonate Precipitation (MICP) Technique

Micro-biological geotechnics is a relatively young and dynamic field where microbiological methods are employed to address geotechnical issues. Microbially induced carbonate precipitation (MICP) is one such sustainable method, which enables cementation in loose sandy mass through calcium carbonate precipitation. Among a series of possible mechanisms (i.e. photosynthesis, sulphate reduction, de-nitrification, iron reduction and urea hydrolysis) to attain MICP, urea hydrolysis associates with greater efficacy and ease of practice. In the present study, widely accepted urease positive microorganism was employed as a source of urease enzyme which helps in biocementation process. Additionally, the effectiveness of MICP technique on sand stabilization and the role of particle sizes on the development of cementation bonds were investigated. Unconfined compressive strength (UCS) and hydraulic conductivity (k) tests were performed on samples treated with 1 M urea-calcium chloride cementation solution. To further endorse cementation of sand particles, microstructure analysis such as scanning electron microscopy (SEM) was performed. The detailed analysis showed that MICP has the potential to bind the particles through bio-mineralization which was further warranted by microstructure analysis. SEM images clearly disclosed mesoscopic and microscopic semblance of calcium carbonate precipitation on sand particles, resulting in the stabilization process.

Vishal Khanna, Umesh Chandra Sahoo, B. Hanumantha Rao

An Experimental Study on Effects of Non-plastic Fines on Engineering Properties of Sand–Silt Mixture

Sandy soil as a foundation material largely depends on the engineering properties of a soil governed by its physical properties and behaviour, containing less or more amount of fines obtained through dredging operation. As IS: 6403-1981 and NAVFAC depicts approximate correlations between SPT N-value, angle of internal friction, relative density and dry unit weight for cohesionless material. But, the effect of a different range of percentage of fines on different sand gradations is not well covered. Hence, an attempt has been made to establish a relationship for different gradations of sand with different amount of fines. An experimental study on the sand along with silt under different conditions was conducted. The reconstituted well-graded samples containing different amount of silt, i.e. 0%, 5%, 10% and 15% were subjected to a vibration table for relative density to obtain maximum and minimum dry density. For the shear strength and consolidation parameter, samples were subjected to direct shear test and consolidation test at three relative density, i.e. 30, 60 and 90% at the displacement rate of 0.25 mm/min under the dry and saturated state. Laboratory results depict that up till transition fines content the angle of internal friction increases and a further increase in fines it decreases. Also, the compressibility increases for different relative density. From the results, it is observed that the percentage of fines alters the engineering behaviour of sand.

Saraswati Pathariya

Effect of Vertical Reinforcement on Settlement and Displacement in Reinforced Soil Under a Three-Dimensional Framed Structure

Soil reinforcement is a technique for improving the mechanical properties of soil. In recent years, the use of reinforced soils has increased widely due to its satisfactory performance and cost effectiveness. Many studies have been carried out on reinforced soil with conventional horizontal reinforcement. The main disadvantage of horizontal alignment of reinforcement is that it requires large-scale excavation of soil, which destroys the strength of soil developed over the years and is also expensive. In this research, studies have been carried out on soil reinforced with vertical reinforcement by considering soil–structure interaction. For this purpose, a four-storey three-dimensional frame structure with isolated footing resting on both un-reinforced and reinforced soil has been considered. Soil has been reinforced with HYSD bars of Fe 500 grade and reinforcement is provided only below footings. The frame section and soil continuum have been modelled and analysed using finite element-based software program SAP2000. The size of the soil mass considered is 153 m × 95 m × 20 m. Parametric studies have been carried out by varying reinforcement length and reinforcement spacing. The study revealed that the displacements in soil can be reduced by the inclusion of vertical reinforcement. Settlement is reduced in the range of 4.45–16.79%. Horizontal displacement along longitudinal and transverse direction is reduced in the range of 7.37% to 26.31% and 8% to 33.24%, respectively. Differential settlement in reinforced soil is reduced by 30.34% when compared with that of un-reinforced soil.

P. Manjunath, H. M. Rajashekhar Swamy, Nayana Patil

A Review on Soil Liquefaction Mitigation Techniques and Its Preliminary Selection

Soil liquefaction is a phenomenon where a saturated cohesion-less soil substantially losses its strength as a result of reduction in effective stress and/or increase in the pore water pressure due to sudden change in stress condition, causing soil to behave like a liquid. Liquefaction may cause detrimental effects on infrastructures, loss of life and lifeline systems, which was historically observed in numerous earthquakes with major manifestations in 1964 Niigata, Japan, 1964 Alaska and recently in 2001 Bhuj, India, earthquake. In order to mitigate liquefaction effectively, knowledge about prevailing site conditions, subsurface stratification, project constraints, ground water table fluctuation, details of past seismic events, etc., and thorough technical knowledge of various liquefaction mitigation techniques is required. This article provides a concise summarization of various soil liquefaction mitigation techniques in current state of practice. Based on the mechanism of soil improvement, methods were categorized as (a) hydraulic modification, (b) soil structure densification and (c) reinforcement of soil. Finally, each of the listed methods was evaluated by generating a feasibility index through rated score analysis. These ratings were established on the basis of available literature while considering equal weightages to technology selection parameters. It is intended that the calculated feasibility index will serve geotechnical professionals by eliminating least feasible methods for given site conditions during initial stage of project.

Punit Bhanwar, Trudeep Dave

Geopolymer Stabilization of Soft Clays—An Emerging Technique

Large tracts of soft clay deposits are present in many world nations especially along their shore lines and estuaries. These deposits are characterised by their high compressibility with low shear strength making them unsuitable to serve as foundation bed. However, in view of enormous economic activity along the coasts, large-scale infrastructure development becomes inevitable. In view of this, the soft clay deposits are to be improved by suitable methods of stabilization. In this direction, stone columns, preloading with or without vertical drains, deep lime or cement mixing and electro-osmosis have been popularly used across the world. In the recent years, efforts are being made to use geopolymer technology as an alternative to lime/cement mixing as an attempt to reduce the carbon footprint. Besides carbon footprint reduction, several researchers (Duxson et al. in J Mater Sci 42(9):2917–2933, (2007) [1]; Majidi in Mater Technol 24(2):79–87, (2009) [2]; Neupane et al. in Mech Mater 103:110–122 (2016) [3]) reported the technical advantages of high early strength, extraordinary durability, resistance to chemical attack and ability to immobilize toxic atoms for geopolymer compared to conventional lime/cement. Keeping in view these recent trends in geopolymer technology, an attempt is made to study the influence of ground granulated blast furnace slag (GGBS) binder with different molarity of activator, the sodium hydroxide (NaOH). The soft clay is simulated by preparing the clay paste at 0.75, 1.0 and 1.25 times the liquid limit water content. At these initial clay consistencies, the influence of GGBS and NaOH is studied. From this study, it is revealed that the unconfined compressive strength of stabilised clay increases with increase in activator to binder (A/B) ratio and curing period for any binder content. Increased molarity of activator has little influence on the strength gain. The strength gain is observed to be higher at higher initial consistency of clay.

V. Bhavita Chowdary, G. Aravind, V. Ramanamurty, Rakesh J. Pillai

Slope Stability Analysis for an Airport Runway in North-East India

The development of infrastructure in hilly regions requires cutting of slopes and applying slope stabilisation techniques to prevent landslides. In this paper, the results of slope stability analysis are presented for a newly constructed airport in north-east India. This study was conducted on an upcoming airport runway in a hilly region. The slope stability analyses for the retaining structures on the side of the runway are performed using computer simulation. These simulations are used to analyse static and pseudo-static stability of slopes. The stability of slopes is checked using Morgenstern-Price method, which is based on limit equilibrium. An RCC cladding wall supports the cut slopes. Cable anchors and rock bolts support this wall. Further, self-drilling anchors (SDAs) are used on the open ground slopes to resist local failures. At some places, cable anchors are used in combination with self-drilling anchors to support steep slopes. The study shows that long anchors with shear reinforcement are the best solution to stabilise steep ground slopes.

Yamini Grover, Pranjal Mandhaniya, J. T. Shahu

Impact of Wetting–Drying Cycles on Swelling Behavior and Micro-structural Analysis of Stabilized High Plastic Clay

Clay minerals of expansive soil are susceptible to swelling and shrinkage due to moisture variation. Distress occurs to expansive clay soils due to drying and wetting cycle, which directly affect the lightweight structures. The effect of cyclic wetting–drying phenomena can be reduced by improving the soil. In this study, the high plastic clayey soil was treated with industrial waste granulated blast furnace slag and bagasse ash, and the influence of wetting and drying cycle on swelling characteristics of treated soil has been investigated in laboratory condition. Such investigation is needed to check the durability of stabilizer to modify the expansive soil. High plastic clay was stabilized with different proportion of BA and GGBS to get optimum mix. Both untreated and (0 and 28 days cured) treated expansive clay were analyzed for wetting–drying cycles. Variations in consistency limits of both natural and untreated clay were investigated. The micro-structural studies were also conducted by X-ray florescence and scanning electron microscopy (SEM). The finding indicates that these waste products reduce the gradual deformation of stabilized high plastic clayey soil subjected to drying and wetting cycles. The result of this research revealed that bagasse ash can be used in soil stabilizer as a pozzolanic material in combination with ground-granulated blast furnace slag to improve swell–shrink behavior.

Khushbu Gandhi, Shruti Shukla

Strength Characteristics of Subgrade Soil Stabilized with Plastic Bag Strips

Plastic is perhaps the most dangerous scrap and pollution that it causes and has become a villain to the society. For the betterment of our planet, we must use and recycle the plastic in a fruitful way. During recycling process due to melting of plastic, toxic gases are released. One of the effective ways to manage plastic waste is using it for soil stabilization. This study investigated the possibility of utilizing plastic bag waste for the reinforcement of soils. The effects of variation in thickness and aspect ratio on strength characteristics were studied in this work. The various thickness ranges used were 15, 30, and 45 μm, and waste plastic carry bag strips were added at 0.1, 0.2, and 0.3% concentration. The unconfined compressive strength test was conducted, and the results obtained favorably suggest that up to an optimum value, shear strength increases with increase in plastic content. An improved UCS value was achieved at 0.2% plastic content having an aspect ratio of 2.5. Results of experimental studies on soil reinforced with plastic waste showed that plastic can be effectively used as stabilizing material so as to solve environmental issues.

A. Vismaya, Monica Simon, P. K. Jayasree, Leema Peter

Effect of Kaolinite Clay and Different Sand Gradation Mixture on Compaction Parameters

In nature, various types of soils are distributed in such a way that they are found together. It is very much difficult to find clay, sand, silt, gravel in a pure condition. Also, these soils (clay, sand, silt, gravel) have different geotechnical properties. Although various researchers have focused on effect of clay particles on various geotechnical properties of sand–clay mixture. But, sand is available in different size and gradations. So, the effect of sand gradation and various particle size on geotechnical properties of sand–clay mixture is still not clear or very less information available about that. In this study, effort have been made to understand the effect of clay particles (kaolinite) on compaction parameters (OMC, MDD) of various sizes and gradation of sand. Experimental work involves the preparation of six samples of sand (i.e., three poorly or uniformly graded and three well graded) from procured materials. Poorly graded samples were obtained by following sand size: coarse sand (>2 mm), medium sand (>0.425 mm and <2 mm), fine sand (<0.425 mm). For preparation of well-graded samples, efforts had been made by combining two or three types of sands, i.e., coarse, medium, and fine (C + M, M + F, C + M + F). Kaolinite clay was used as cohesive fine fraction. Different amounts of kaolin clay were added in each of the sample, i.e., 0, 5, 10, and 15%. Preliminary tests were performed on all the three well graded, three poorly graded as well as on kaolinite clay in pure condition for finding out the physical properties of the soils. (i.e., Atterberg’s limits, grain size distribution, specific gravity). Relative density test was performed for finding out the density of all the sand samples at 0% kaolin content ant 70% relative value was adopted. For all other sand–kaolin mixture (5, 10, 15%) standard proctor tests were carried out. Results indicated that among all the samples (coarse + medium + fine + 15% kaolin) exhibits greater maximum dry density (MDD) and lesser optimum moisture content (OMC) while (fine + 5%kaolinite) has lesser maximum dry density and greater optimum moisture content. So, from the results we can say for (C + M + F + 15%) sample all the particles are well arranged so the gap between the particles are minimum so the MDD of the sample goes to increase.

Nafisa D. Shaikh

An Experimental Study on Improving the Performance of Silty Soil by Encased Granular Column Using Shredded Tire Chips

Use of stone/granular columns is considered as one of the influential soil-stabilizing methods that can increase the load bearing capacity of soft soil foundations considerably. Recently, it has been reported that the stone aggregate can be replaced by shredded tire chips partially or fully, which will lead to an economical design solution for a granular column. On the other hand, the tire chips are waste materials, and if used for major geotechnical applications, this will not only solve the environmental problems but also result in considerable savings in terms of natural resources thus making the construction method sustainable. This paper presents the results of an experimental study carried out with shredded waste tire chips as a substitute fornatural aggregates and also their effect on granular column behavior. Typical size ranges of tire chips used in the study were 10 mm × 10 mm × 10 mm. The aggregates used were passing through 12.5 mm and retained on 10 mm sieve. Geogrid encasement, namely combi-grid, was used in experimental investigation. A series of small-scale model tests was performed on ordinary granular column (OGC) as well as granular columns made up of shredded tire chips and aggregates and encased with combi-grid (EGC). All the granular materials were compacted at 90% relative density. The strain rate for all the tests were maintained at 1.2 mm/min. The results of the study indicate that the load-carrying capacity significantly increased even the granular column made of 100% tire chips. It has also been observed that ordinary stone column made of aggregates without encasement can be completely replaced by the encased granular column made of 100% tire chips. However, the load-carrying capacity of encased stone column made of aggregates found to be higher than that of tire chips.

Muni Pradeep, Anil K. Choudhary, Awdhesh K. Choudhary, S. K. Shukla

Strengthening of Equipment Foundations on Loose Soils of a Power Plant in Eastern Uttar Pradesh

Small equipment foundations of a power plant placed on a 5–6 m thick poorly compacted fill underlain by rock experienced excessive settlements. Strengthening measures adopted included installing micro-piles extending to the top of rock and filling large voids in the fill with a thick grout of cement and sand. This highlights the importance of proper compaction as well as the need to test the bearing strata adequately before constructing foundations on fill.

Ravi Sundaram, Sanjay Gupta, Mohit Jhalani, Jitendra Kumar

Experimental Study of Stabilization of Expansive Soil Mixed with Sawdust and Marble Dust

This paper aims at studying the effects of marble dust powder and sawdust content as mixtures in clayey/expansive soil and its engineering properties. Expansive soils have high potential for shrinking or swelling. Due to this phenomenon, surface crack occurs resulting in openings during dry season. The expansive soils have variable strength based on its moisture content and have large volume change leading it to unfit for the construction purpose. Based on Indian standard guidelines, CBR, UCS, and standard proctor tests were conducted on the soil sample mixed with 2–10% sawdust and 2–15% marble dust powder to determine the maximum dry density and optimum moisture content at varied percentages of waste admixtures in the soil. The admixtures had an overall positive effect on the geotechnical properties of soil and they can be used as a measure to improve soil strength and contribute toward decreasing the environmental impact of waste materials on our surroundings and it also resolves the problem of waste disposal.

Sukanya Sharma, Kalpana Verma, J. K. Sharma

Investigation of the Microstructure of Brahmaputra Sand Treated with Bacillus megaterium-Mediated Single-Dosed Bio-Cementation

The bio-mediated soil improvement has promising capabilities to provide sustainable aid to the geotechnical challenges. The geotechnical behavior of the soil can be modified utilizing bio-mediated processes. Most of the studies on the bio-mediated soil improvement focuses on a particular bacteria Sporosarcina pasteurii. This study utilizes urease positive bacteria Bacillus megaterium (NCIM 5472) as an alternative to S. pasteurii and Brahmaputra riverbank sand for the investigation of bio-cementation in the soil. In this study, the primary characterization of B. megaterium has been reported. The qualitative urease activity of the bacteria has been assessed with Urea Agar Base (Christensen), and quantitative analysis of urease activity assay has been evaluated by the phenol-hypochlorite method. Quantitative calcite precipitation has been evaluated at equimolar cementation solution. After the characterization, single dosing of bacterial broth solution mixed along with cementation solution (one pore volume) is introduced to Brahmaputra riverbank sand, and the microstructure of the sand has been investigated with the help of field emission scanning electron microscope (FESEM) images. The influence of bio-cementation was observed significantly on the microstructure of Brahmaputra riverbank sand in the form of bridging of the calcite precipitated. This study is a preliminary study to investigate the applicability and potential of the bacteria B. megaterium for bio-mediated soil improvement. The study concludes that the bacteria B. megaterium is moderately urease active, and it has the potential for bio-cementation.

Anant Aishwarya Dubey, Rituraj Devrani, K. Ravi, Lingaraj Sahoo

Numerical Simulation of Liquefaction Mitigation by Using Grout Under Existing Building

Ground improvement using jet grout columns is a well-known technique to mitigate liquefaction hazard in sand stratum under existing building. However, the performance of conventional jet grout reinforcement technique has not achieved the sufficient level yet in terms of reducing shear strains and excess pore water pressure generated within the liquefiable soil layer. Therefore, a new countermeasure method, using small diameter jet grout column with additional horizontal slab, is introduced to control the shear deformation and excess pore pressure more effectively. To determine the efficiency of the new countermeasure method, numerical studies on unimproved and improved ground were separately performed in this study. The effectiveness of jet grout column with horizontal slab was evaluated by comparing the changes in excess pore water pressure, acceleration as well as distribution of shear stress and shear strain in the liquefiable soil before and after improvement. The results showed that the new liquefaction mitigation method offers positive effect on control of excess pore water pressure and shear deformation.

Myat Myat Phyo Phyo, Hemanta Hazarika, Hiroaki Kaneko, Tadashi Akagawa

A Study on the Effect of Phosphogypsum on the Properties of Subgrade Soil Mixed with Fly Ash

The present study is an attempt to enlighten the direction of utilization of industrial wastage materials such as phosphogypsum and fly ash, by mixing them with subgrade soil to improve the load-bearing capacity of silty-sandy soil. With the increasing urbanization, industrial growth and installation of various plants generate a huge volume of wastes. The soil subgrade plays a pivoted role in the load-carrying capacity in both flexible and rigid pavement. For the laboratory investigation, the silty-sandy soil samples have been collected from Rabindranath Tagore Hostel inside the N.I.T. Agartala campus, Tripura, India. Each soil sample has been collected from the depth of 3 m below the natural ground surface. The fly ash sample has been collected from Kolaghat Thermal Power Plant, West Bengal, India. Different tests were performed as per the requirements of Indian Standard Codes to know the compaction properties, unconfined compressive strength, and C.B.R. values of the original soils and the soils treated with fly ash and phosphogypsum. It is observed from the test results that, for soil blended with fly ash and phosphogypsum, the values of C.B.R. and unconfined compressive strengths are significantly higher compared to that of untreated natural soil and soil mixed with phosphogypsum. From the tests, it can also be concluded that soil content with 30% fly ash and 6% phosphogypsum can be used as a subgrade material. Also, the thickness of the subgrade layer can be reduced as the subgrade is good. So the construction cost of the pavement may be reduced.

Tanmoy Maity, Sanjay Paul

Effect of Coir Fiber on Compressibility Behavior of Clayey Soil

The significant high compressibility and low shear strength of clayey soil impose challenges to the civil engineers. Use of coconut coir fiber for improving soil property was advantageous because they are cheap, locally available and eco-friendly and used as a reinforcement material. Coconut fiber is a natural fiber extracted from the husk of a coconut. This paper focuses on the experimental investigation on the effect of coir fiber on the compressibility characteristics and permeability behavior of the clayey soil. Coir fiber was added in different percentages (viz 0.3%, 0.4%, 0.5%, 0.6%, 0.7% and 0.8%) to the soil sample with 10 mm length, and the effect of coir fiber in compressibility and permeability characteristics of the soil was studied. Results show that compressibility decreased and the coefficient of consolidation increased on the addition of the coir fiber. Coir fiber of different percentage is used for the study, and optimum moisture content and maximum dry density were used for preparing the soil sample. An optimum percentage of coir fiber for the enhanced properties of soil was found out, and also, the coefficient of consolidation, compression index is found out from consolidation test with different loading rates. The compression index (cc) decreases with the inclusion of coir fibers in the soil up to certain fiber content and increases thereafter.

K. S. Sajini, K. Niranjana

Ground Improvement of a Liquefiable Soil by Granular Piles

Liquefaction is a physical process by which soil sediments below the groundwater table temporarily loose strength and stiffness, and initiate to behave as a viscous liquid rather than a solid. In addition to earthquake and rapid application of large loads, a soil may liquefy due to construction activities like blasting and during ground improvement by vibro-flotation and dynamic compaction. Liquefaction phenomenon may cause unrecoverable damage to a building and other civil structures. Hence, it is very important to know about the liquefaction potential of a construction site so that suitable protection measures can be adopted before construction. Granular piles are one of the popular treatment methods to make the soil less prone to liquefaction. In this study, liquefaction potential of a project site at Darbhanga in Bihar has been evaluated (by method developed by Youd et al. 2001) from the borehole data where groundwater table is at a shallow depth. Once the liquefiable depths in substrata are identified, granular piles along with the shallow foundation have been selected as the best viable foundation solution based on the soil characteristics determined. The design of granular piles consists of certain parameters, such as their diameter, total length, number of piles and their arrangement at site. Use of granular piles will not only improve soil strength significantly but also will provide drainage option for the risen groundwater at high pore water pressure which may be generated during an earthquake event. To present the benefit of granular piles over conventional RCC piles, a comparative design and cost assessments of granular piles with RCC piles were also performed. It has been observed that a significant reduction of construction cost and settlement control may be achieved by granular piles over RCC piles. This kind of study will help in selecting an appropriate liquefaction measure and its design, leading to safer construction of the civil structures.

Koushik Pandit, Pradeep Kumar, Gaurav Sharma

Influence of Textile Polyester Waste Fiber on Strength and Subgrade Properties of High to Medium Plastic Clay

In India, a major portion of total land area is covered by high to low plastic clayey soil. Of this, a large proportion is expansive soil. Structures constructed over this expansive soil may be severely damaged due to its high swell-shrinkage behavior. So, such soils need to improve its strength, durability and to prevent erosion. Various studies have been carried out on expansive soils to improve its properties. Soil stabilization is one of the promising techniques used to improve the geotechnical properties of soil and has become the major practice in construction engineering. This study works to evaluate the improvements in properties of CH–CI soil of south region of Surat by adding textile polyester waste fiber. For improvement of engineering properties, this fibers are used as reinforcement by varying percentage of 1, 2 and 3%. The soil parameters such as shear strength, subgrade characteristics tested under UCS and CBR. These values are compared to that of a control specimen. Author critically remarked as CH soil has different characteristics as compared to CI soil under this test. Experiment results show this fact that using textile polyester waste fibers leads to increasing shear strength, dry density, CBR value and reduction in plasticity index and free swell index in CI soil as compared to CH soil. Analysis of result obtained from experiments may be proving the effectiveness of this product to construction site having this both types of soil. The expansive soil can be successfully stabilized by the combined action of fibers with soil.

Pratima A. Patel, Yati R. Tank

Effect of Silica Fume and Induction Furnace Slag in the Compaction and Strength Characteristics of Black Cotton Soil

The present investigation brings out the experimental outcomes of the influence of two industrial solid wastes on black cotton soil. It evaluates the changes in compaction and strength characteristics of the black cotton soil on addition of these solid wastes. Disturbed soil sampling had been done, and as per Indian classification system, the soil is classified as CH soil. The virgin soil is mixed with varied percentages of silica fume and induction furnace slag independently, and its effect on compaction characteristics was ascertained. The proportions identified for silica fume and induction furnace slag are in the order of 5–20% of dry weight of soil with an incremental increase of 5%. The optimum percentage of silica fume was obtained from the compaction characteristics of the soil. After choosing optimum percentage of silica fume, further, the compaction and strength characteristics of the soil were ascertained with optimum percentage of silica fume and varying percentage of induction furnace slag, i.e., 10 to 20% with 5% increase. The results shows that the maximum dry density for BC soil + 10% SF + 20% IFS is 1.63 g/cc, and UCS for BC soil + 10% SF + 15% IFS is 138.76 kPa.

Winny Joseph, R. Sridhar

Experimental Studies on Influence of Alccofine and Calcium Chloride on Geotechnical Properties of Expansive Soil

Expansive soil deposits occur in the arid and semi-arid regions in the world. They cover a major portion on the geographical area in the world and about one-fifth the area of India (approximately 300,000 km2); such soils are popularly perceived as black cotton soils and found extensively in Andhra Pradesh, Gujarat, Karnataka, Madhya Pradesh, Maharashtra and Tamil Nadu. The present study is to elucidate and efficacy of materials as an additive in improving the engineering characteristics of expansive soils. An experimental programme has evaluated the effects of alccofine-1203(3%, 6% and 9%) and Cacl2 (0.25%, 0.5%, and 1.0%) contents on the FSI, swelling potential, swell pressure, plasticity, compaction, strength, hydraulic conductivity, SEM, XRD, cation exchange capacity (CEC), characteristics of expansive soil. Both admixtures were added independently and blended to the expansive soil. Mixing of both admixtures into expansive soil results shown that plasticity index, hydraulic conductivity, swelling properties of blends decreased and dry unit weight and unconfined compressive strength is increased in combination of soil + 6% of alccofine-1203 + 1% Cacl2, but further more addition of alccofine-1203 and Cacl2 leads to decrease in the unconfined compressive strength. It was found that the optimum quantity of material for favourable combination of soil + 6% of alccofine-1203 + 1% Cacl2 was taken for further study in view of its economy due to lower Cacl2 content.

R. Suresh, V. Murugaiyan

Effect of Various Factors Affecting Electrokinetics Dewatering of Soil Using Conductive Geotextile

Electrokinetic principles are being used in many geotechnical engineering application such as dewatering, decontamination, solid enhancement. Soils in the presence of high water content tend to loose the interparticle bonds, resulting in high compressibility of the soils, low bearing capacity and low permeability of the soil. All these issues lead to increase in settlement values or differential settlements. The presented paper used the process of electrokinetic dewatering to enhance the draining of water and thereby improve the strength of soft soil. The electrokinetic geosynthetics used give technical benefits over conventional electrodes in that they can be formed as strips, sheet, blankets, etc. They are light and easy to install. This paper describes laboratory experiment using polyester cotton-based materials intertwined with copper wires as a cathode and carbon electrode as anode with three types of soil under present investigation. The various factors studied for the same are experimental duration, electrode, voltage gradient and re-run analysis. It is observed that there is an increase in the percentage removal of water content with increase in value of each of the factor with increase in shear strength of the soil in case of effect of electrode.

Kalpana P. Patel, L. S. Thakur, D. L. Shah

Numerical Analysis of Geogrid CFG Pile-Supported Embankment on Soft Soil

This paper presents an optimum design and analysis of CFG pile-supported embankment for the national highway in India. Cement flyash and gravel piles are new approach of ground improvement column technology for the India. These techniques were used in china in many projects as highway and railway embankment for ground improvement. A couple two different dimension embankments 2D FEM model are used in this paper over the expansive soil near Surat City, Gujrat. The present study does with this observation by employing CFG pile support embankment composite foundation and screening its reflection through 2D FEM analyses. The present study on CFG pile variable length affects the slenderness ratio, material properties (Grade) as well as effects of area replacement ratio. The slenderness ratios of pile and thickness of sand layer on the proportion of loads are shared by CFG piles and its settlement response of composite foundation on different levels of vertical load by highway embankment. Results showed the thickness of sand mattress on CFG pile was transmission load effectively as significant thickness of it. CFG pile was efficiently in improving the bearing capacity and reducing vertical settlement of expansive soft soil. Other way results showed that incremental lengths of CFG pile reducing the settlements of composite foundation and increment in diameter of CFG pile effectively improved in bearing capacity of composite foundation. CFG pile material friction angle improves the bearing capacity of foundation system.

N. B. Umravia, C. H. Solanki

Analysis and Modification of Engineering Behavior of Soil Using Plastic Waste Materials

Plastic waste management becomes a serious issue all over the world. Dumping of plastic waste on land without treating it degraded the properties of parent material. The main objective of this study is to demonstrate the use of plastic waste for improving properties of soil and soil subgrade underlying by aggregate base which is applicable in construction of embankment and flexible pavement respectively. Waste plastic water bottles converted into plastic strips with an aspect ratio of 6%. The behavior of randomly distributed plastic strip-reinforced soil system and soil aggregate system was observed by conducting soaked CBR test series with different percentage of plastic strips (0%, 0.5%, 1% and 2%). Results of study show that soil reinforced with waste plastic strips has significant increase in CBR values with respect to unreinforced soil in both the cases. The results also reveal that the 1% of plastic strip-reinforced soil system and soil aggregate system show significant improvement in strength.

Yagnik Solanki, Malay Jambudia, Alka Shah

Stabilization of Soil Using Terrazyme for Road Construction

In developing countries like India, the most important requirement of any project after performance criteria is its economical, feasibility and serviceability criteria. The traditional methods are not economically feasible also time consuming. Hence, it has created a need to discover the other possible ways to satisfy the performance as well as economical criteria. The present paper describes a study carried out to check the improvements in the properties of black cotton soil and red soil with a bio-enzyme, named Terrazyme. Recently, some bio-enzyme stabilized roads were constructed in various parts of India, which are being performing very well. Bio-enzyme improves the engineering qualities of soil, facilitates higher soil compaction densities and increases stability. Bio-enzyme helps in easy mixing with water at optimum moisture content (OMC), and then it is sprayed over soil and compacted. Soil with varying index properties has been tested for virgin as well as stabilized soil with different dosages. The test results indicate that stabilization improves the soil strength up to great extent, which implies that the bearing capacity and the resistance to deformation increase in stabilized soil. The locally available material can be used, and in case of scarcity of granular material, only bio-enzyme stabilized thin bituminous surfacing can fulfill the pavement design requirement. Adopting the IRC method based on soil CBR, the pavement design thickness on stabilized soil also reduces 25–40%. The use of bio-enzyme in soil stabilization is not very popular due to lack of awareness between engineers and non-availability of standardized data.

Varun Sushil Chaurasia, Pawan Prabhunath Pandey, Atulkumar Vinod Mishra, Sandeep Shyamnarayan Gupta, Anuj U. Pawar

Study of Swelling and Shrinkage Characteristics of Expansive Soil Using Silica Gel as an Admixture

Expansive soils are characterized as soil which undergo large volume changes on availability of moisture. The continuous cyclic wetting and drying process cause vertical and horizontal movement in expansive soil which leads to failure of engineering structure erected on such soils (Masoumeh and Masoud in Electronic Journal of Geotechnical Engineering 17:2673–2682, [1]). The expansive soil has very low bearing capacity, high plasticity, high compressibility, low permeability, high swelling and shrinkage properties, due to the presence of montmorillonite mineral. The expansive soil contains the clay particle of medium to high compressibility and covers nearly 20% of geographical area in India which is the concern of study (Zhang and Cao in Journal of Wuhan University of Technology 17:73–77, [2]). In this research, silica gel as admixture is used to aid the properties of parent material. This study aims to conduct soil stabilization of black cotton soil of North Gujarat region by using silica gel in different proportion. In this research paper, silica gel is added 2, 4, 6, 8 and 10% by weight to give comparison between the soil properties of untreated soil and treated soil. Due to the addition of 10% of silica gel by mass in virgin soil, l plastic limit increased by 16.72% and liquid limit decreased by 19.23% which ultimately decreases plasticity index by 57.5. Also it was found that MDD is decreased by 4.3%, and free swell index decreased by 41.56% on addition of 10% silica gel by mass.

Uday Chaudhari, Vanshika Muchhara

Utilization of Geo-Grid for Improving the Strength of Subgrade Layer with Fly Ash

The present study aims at exploring the possibilities of utilization of fly ash and geo-grid for rural road. The performance of fly ash and geo-grid reinforced with soil is studied by conducting California bearing ratio (CBR) test. Studies have been carried out by considering different percentages of fly ash by placing the geo-grid sheets within the different depth positions. The motivation of the present work is to reach the soaked CBR value of a subgrade layer which is above 10%, as per I.R.C.: S.P.-72-2007. Under the soaked condition, the geo-grid shows the maximum penetration resistance and gives greater CBR values. The soaked CBR values of soil–fly ash mixed with geo-grid at different depths of single layer show that the CBR values decrease continuously with the increase in the depth of geo-grid. Also the optimum position of geo-grid to get higher value of CBR is 0.2H from the top of the specimen, where H is the total height of the soil specimen in CBR mould.

Paul Basudeb, Paul Sanjay

Stabilization of Contaminated Soil by Mixing of Corn Husk Fibers

Soil contamination has always been a major cause for land degradation and deterioration of soil properties in various ways. Numerous activities involving the use of petrochemicals on a daily basis, accidents leading to oil spilling, and pipeline or reservoir leakage lead to the contamination of soil. In addition to this contamination is also leading to groundwater pollution, altering the geotechnical properties of soil. The uses of natural fibers incorporated soil as a construction material since ancient times, led to the understanding of the variations in soil properties and also the need to improve these properties to achieve desired construction proficiency. Thus, with this view, this research work deals with the improvement of compaction and strength characteristics of synthetic oil contaminated soil by random mixing of corn husk fibers at different percentages of 1, 2, 3, and 4% by weight of soil. The experimental study was conducted on soil samples which were prepared artificially by mixing synthetic oil at 5, 10, and 15% by weight of soil. Index properties of soil were tested, and then proctor compaction test and CBR tests were conducted in order to observe the changing pattern with the addition of corn husk fiber. Results showed marked improvement in compaction and strength characteristics of soil. The pH value of soil was also determined and results showed a remarkable change in soil characteristics from acidic in nature toward neutralization with addition of corn husk fiber.

Priyanka Roy, Prasun Mukherjee

Laboratory Investigation of Black Cotton Soil—Fly Ash—Steel Slag Mixes

Black cotton soil is one of the major soil deposits in India. They exhibit high swelling and shrinking when exposed to changes in moisture content and hence has found to be most troublesome from engineering considerations. In this study, geotechnical characteristics of black cotton soil with the addition of fly ash (FA) and steel slag (SS) mixes were investigated. FA and SS were added in the varying percentage of 5, 10, 15, and 20% of the weight of black cotton soil. Atterberg’s limit tests illustrated that 5–20% addition of FA and SS in the black cotton soil considerably reduces the volume change potential of the black cotton soil. Addition of FA and SS in black cotton soil also helps in reducing its swelling and shrinkage potential. The strength gain of the mixes not only depends on fly ash and steel slag content but also on mix gradation. The angle of internal friction for all mixes and the cohesion part of the shear strength was higher than that of the black cotton soil owing to strong bonding between steel slag and fly ash particles. Apart from the experimental results, the use of fly ash and steel slag has proven to be an eco-friendly material thereby reducing the dumping and disposal problems associated with fly ash and steel slag.

Mangesh Subhash Ambekar, Hrishikesh Ashok Shahane

Comparison of Compaction Characteristics of Non-conventional Conventional Stabilizers

Roads play an important role in connecting traffic all over the world. It is crucial as it helps to grow and develop a nation. In past decades, ingress of water in the rainy season weakens the road’s soil base. From the beginning of road stabilization, water was one of the main problems. So now researchers have come with an idea of water-proofing the soil and recently, they introduced nano-chemicals. Previous literature surveys show that the presence of only small amount of nano-material in the soil could influence significantly the physical and chemical behaviour of soil. The main objectives of the study are to determine the compaction and shear strength properties of various soil combinations prepared by mixing the nano-chemical solutions, to obtain the optimum dosages of nano-chemical agent corresponding to higher MDD and shear strength values. The nano-chemicals Terrasil and Zycobond are collected from Gujarat, India, for the stabilization studies. Experimental programme is carried out on the clayey-silt soil treated with different dosages of Terrasil, Zycobond and cement. Results obtained are compared and studied. UCS strength is found to be increasing with increase in dosage of stabilizer and curing period. The optimum dosage of Terrasil and Zycobond is obtained as 0.8 kg/m3 by weight of soil and also the strength maximum for 7% cement content. This improvement may be possible due to the reaction of the chemical with the soil particles and as a result Terrasil waterproofs the surface and Zycobond improves strength.

M. S. Gayathri, Sujit Kumar Pal

Effects of Delay Time on Compaction and Strength Properties of Stabilized Granular Soil

Weak and marginal soils are conventionally stabilized with chemical stabilizers like lime and cement. During construction, sometimes inevitable delays occur between mixing of stabilizer with the soil and compaction, which have adverse effects on the geoengineering properties of the stabilized soil structures. The present study emphasizes the effects of delay time on compaction and strength properties of a granular soil stabilized with three different stabilizers, i.e. lime, cement and slag-based geopolymers. In this study, these three different stabilizers were added with soil in different proportions varying from 0 to 15% of the dry soil, and the effect of time lag was studied individually. The optimum moisture contents (OMC) and maximum dry densities (MDD) of these mixtures were determined after a time lag of 0, 3, 6, 12, 24, 48, 72 and 168 h. Further, cylindrical specimens of size 36 mm diameter and 72 mm length were prepared for all these mixes compacted to MDD at OMC taking into the effects of delay. Before conducting the UCS test, these specimens were cured at an average temperature of 30 °C for 0, 7 and 28 days in closed secure environment for assuring the prevention of moisture loss while curing. It was observed that the delay time significantly affects the OMC and MDD of mixes, and it is more noticeable in case of cement and geopolymer binders than the lime. Similarly, delay time affects the strength of cement and geopolymer stabilized mixes more adversely than lime stabilized mixes.

B. Siva Manikanta Kumar, Ch. Sreenivasulu, Suresh Prasad Singh

Strength and Deformation Characteristics of Lime-Admixed Black Cotton Soil Reinforced with Sisal Fibres

Sustainable ground improvement techniques have led to the use of natural fibres to improve the shear strength properties of soil. Lime was admixed to black cotton soil starting from 1, 2, 3, and 4%, and optimum lime content was arrived at based on maximum value of dry unit weight and corresponding water content from compaction test. Using the optimum lime content thus obtained, black cotton soil was reinforced with randomly distributed sisal fibres of average length 10–20 mm and analysed for shear strength in terms of unconfined compression test. Sisal fibres were added in varying percentages starting from 0, 0.5, 1, 2, and 3%, and compaction characteristics were assessed. Remoulded specimens were prepared to have corresponding maximum dry unit weight obtained from compaction test and were tested for unconfined compressive strength to study the effect of curing with and without lime at different periods of 0, 10, 20, and 30 days. The result indicated sisal fibre content of 0.5% and indicated maximum shear strength with and without optimum lime. The surface characteristics of sisal fibre-admixed soil along with lime using X-ray refraction and scanning electron microscopic study revealed better bonding strength between soil and sisal fibre.

Jairaj, M. T. Prathap Kumar, M. Aashish, R. H. Basava, Y. Neeraj, F. M. Sabira

Compressibility Studies on Cochin Marine Clay Stabilized with Fly Ash and Lime Columnar Inclusions

The study focuses on the use of lime, fly ash and combination of these materials as columnar inclusion for improving the strength and compressibility characteristics of soft Cochin marine clay. Large-scale consolidation tank was used to study compressibility characteristics. A group of five columns of different materials (lime, fly ash and a combination of both) were installed in the tank filled with marine clay in its natural moisture content. The consolidation test was continued till the settlement rate reached a value less than 1 mm/day for the different applied pressures. It was observed that clay alone took 91 days to reach target settlement, whereas the lime column took 29 days, fly ash column took 51 days and 1:1 lime–fly ash column took 39 days. The shear strength of the clay increased with the installation of the columns of different materials.

Aswathy Rajendran, G. Sanoop, Sobha Cyrus, Benny Mathews Abraham

Load Settlement Behaviour of Soft Soil with 3D-Reinforced Sand Piles

Nowadays due to scarcity of land, structures are built in sites with the available soil conditions including soft soil layers. In site conditions where deep foundations are not a viable solution due to economic considerations, the existing foundation soil has to be modified for better bearing capacity and reduced settlement. In the present scenario, a wide variety of ground improvement techniques is available including modification by inclusions and confinement. The use of sand piles is a proven technique to improve the desirable properties of soft soil. In this study, the effectiveness of sand piles is further improved by introducing 3D elements into the sand piles. A series of laboratory plate load tests were conducted on a model footing resting on soft clay reinforced with sand pile with and without 3D elements in it. The tests were conducted using two different shapes of 3D elements, namely tetrapod and pentapod. Also, tests were conducted for different volume ratios of 3D elements as 1.82, 2.27 and 2.73% at a constant relative density. Between the two shapes, pentapod elements were more effective due to better confinement of soil between the legs owing to the geometry. Also, the bearing capacity is improved by increasing the volume content of 3D elements from 1.82 to 2.73%. From the results, it can be found that for clay only, the bearing capacity at a settlement ratio of 4% is 94.86 kN/m2. The bearing capacity of the clay is improved to 122.76 kN/m2 when reinforced with sand pile only at 50% relative density. For same relative density of sand pile, the bearing capacity of clay is improved to 167.40 and 212.04 kN/m2 for sand piles-reinforced tetrapod and pentapod elements, respectively, at volume content of 2.73%. This shows that 3D elements can be effectively used in sand piles for improving the properties of soft clay.

O. Megha, M. N. Sandeep, K. S. Beena

Geotechnical Properties of Lime and CKD Admixed Biosolids

The amount of waste generated due to impact of urbanization has increased worldwide. To evolve sustainable use of materials, it is imperative to use treated waste materials as a good step in waste management. The objective of present investigation is to verify the improvement in geotechnical properties of biosolids which is one of the waste materials generated from wastewater treatment plant. In the present study, the biosolid was admixed with different percentage of lime. The optimum lime content (OLC) was determined based on compaction characteristics. To further improve its geotechnical properties, cement kiln dust (CKD) was added along with OLC, and various geotechnical properties were determined. It was found that the blended biosolids with 20% OLC along with 10% CKD showed significant improvement reduction in liquid limit, increase in shear strength and CBR, indicating its potential application as a subbase material in road construction.

M. T. Prathap Kumar, N. Karthik, Basavalinga, M. N. Annappa Hemanth, D. R. Nagesh Kumar

Effect of Soil Slope on Failure Mechanism of Soil-Nailed Structures by Aluminum Nails and Bamboo Nails

In the present day scenario, improvement of ground is necessary in various occasions due to wide range of construction requirements. Various ground improvement techniques have been developed over the past few years. Increasing the load carrying capacity by inserting steel bars generally termed as soil nails is one of the effective techniques. These are mostly used in improvement of soil slopes. Wide range of materials can be used as soil nails. In the present study, hollow aluminum tubes and bamboos were used as soil nails for improving the ground characteristics. Model tests were performed for soil slope with different conditions of nail inclination. Further, these test results are compared with unreinforced soil. Parameters considered for the study are nail inclination and soil slope. Three nail inclinations are considered for the present study; they are 0°, 15°, and 30° with horizontal axis and two soil slopes they are 45° and 60°. Constant parameters considered for the study are soil, height, nail length, and nail pattern. The results obtained are compared with the conventional unreinforced soil slope for each case and curves for load versus settlement were developed for the same. From experimental results, soil slope with 0° nail inclination with horizontal axis gives the maximum load carrying capacity in all the cases, followed by 15° nail inclination with horizontal axis and then 30° nail inclination with horizontal axis.

Venkateswarlu Dumpa, G. Kumar, Chandra Shekhar Rayi, M. Anjan Kumar, G. V. R. Prasada Raju

Stabilization of Clays and Clayey Soils Using Polycom-A Polyacrylamide Additive

The aim of this study is to assess the benefits of using Polycom a polymer-based additive to improve various performance-related properties of clays and clayey soils. Polycom is a commercially available polymer, which has a wide range of applications related to the improvement of various properties of soils. Generally, the substance is used in road construction as a means of stabilizing the soil movement due to changes in moisture content. Studies by the University of Adelaide have indicated that the addition of Polycom to the clay had a significant influence on decreasing the permeability of the respective compacted clay liners (CCL). Three types of soils namely clay of high compressibility and two clayey sand samples are tested in the laboratory by adding Polycom-mixed water. Wet application method is used to stabilize the soils in which the dry Polycom powder is mixed with water that is to be applied to the soil to obtain the optimum moisture content. The Polycom reacts with the water such that a highly viscous solution forms. The effect of Polycom on engineering properties of soils is investigated by dry density vs moisture relationship, unconfined compressive strength (UCS), and direct shear tests. Results show that clay of high compressibility (CH) showed appreciable improvement in strength in terms of UCS with the stabilizer for different curing periods. The improvement in UCS is about 160% with respect to strength of untreated soil. Similarly for clayey sand (SC), the increase is about 150% and 40% in cohesion and angle of internal friction, respectively, for 5 days of curing with respect to untreated soil strength.

M. Padmavathi, V. Padmavathi

An Experimental Investigation of Properties of Black Cotton Soil Treated with Copper Slag and Groundnut Shell Powder

Expansive soils have large volume changes due to the variation of water content. Therefore, expansive soils are also known as problematic soils due to its expansive nature. The black cotton soil has very low bearing capacity, high plasticity, high compressibility, low permeability and high swelling and shrinkage properties due to the presence of montmorillonite mineral. Due to these properties, black cotton soils are problematic soils. Therefore, it is necessary to improve its properties by using soil stabilization method. This study aims at conducting stabilization of black cotton soil of Bharuch region in Gujarat state by using combination of two soil stabilizing agents: copper slag and groundnut shell powder. In this research, copper slag is added 5% and 10% and groundnut shell powder is added 2% and 4%, respectively. The research gives comparison between the soil properties of non-treated and treated black cotton soil. Various laboratory tests are carried out such as specific gravity, liquid limit, plastic limit, shrinkage limit, free swell index, standard proctor compaction test, unconfined compressive strength test for both the cases by taking IS:2720 as reference. These laboratory tests results can be helpful to engineers to carry out soil stabilization on field during construction.

Pooja Pandya, Bhoomi Kamdar

Experimental Investigation of Silty Soil Treated with Sodium Lignosulfonate

Soil stabilization refers to the process of changing soil properties to improve strength and durability. There are many techniques for soil stabilization, including compaction, dewatering, and by adding chemicals to the soil. Out of these, chemical stabilization is one of the most effective and popular techniques, which has been practiced successfully in the field. There are several chemical additives such as lime, cement, fly ash, and rice husk. Most recently, lignin is an industrial by-product that has been identified as a chemical additive for stabilization of soil mass. Besides, lignin does not have any adverse effect on the environment. In view of this, the behavior of lignin-stabilized soil has been investigated in the present study. Results obtained from unconfined compressive strength tests indicate that the performance of lignin-stabilized soil increases with increase in percent of lignin content. However, it has been observed that the performance of stabilize soil reduces beyond 3% of lignin content. This is possibly because the soil particles completely get coated with lignin if it increased beyond 3%, thereby mobilizes strength at the surface of two lignin particles, which has lesser bonding strength than the strength mobilized at soil lignin interface. Therefore, it can be stated that the optimum percentage of lignosulfonate giving maximum performance of stabilized soil mass should be about 3% by weight.

Abhijeet Gupta, Awdhesh K. Choudhary, Anil K. Choudhary

Evaluation of Strength Characteristics on Black Cotton Soil–Stone Dust Mixtures Reinforced with Shredded Tyre Rubber

Disposal of waste materials is a big problem with exceptionally growing up country like India. Rapid industrialization, population explosion, an extensive repletion of natural resources produces large quantities of waste materials which cause serious geo-environmental problems. Expansive soil swells and shrinks with regular wetness variation make structures founded on it unhinged and in practical cause huge economic loss in transportation division. In this, find out the waste material stone dust as a stabilizer and shredded tyre rubber which acts as a reinforcing material is selected. In the present study, stone dust blend to black cotton soil in changeable percentages of 5, 10, 15 and 20% by dry weight and shredded tyre rubber in varying of 1, 2, 3 and 4% added to black cotton soil stabilized with optimum percentage of stone dust. The treated and untreated samples were subjected to compaction, CBR (soaked and unsoaked) and unconfined compressive strength tests. The experimental values proved that there is a significantly increase in strength parameters for the black cotton soil added with stone dust and shredded tyre rubber combination.

D. S. V. Prasad, K. Bharath Kumar, K. Sridevi, K. Vishalakshi, G. V. R. Prasada Raju, K. Jyothi Raju

Experimental Study on Load-Settlement Behaviour of Granular Stone Column in Expansive Soil

In today’s construction industry as land reclamation is increasing rapidly so ground improvement has become necessity. Ground improvement is carried out by increasing vibration, structural fill or reinforcement, vegetation, admixtures, etc. out of all the methods, the stone column technique is a very effective method of improving the strength parameters of soil like bearing capacity and reducing settlement, particularly, for the construction of flexible structures, such as road embankments, oil storage tanks on soft soils. It offers a very economical and sustainable alternative to piling and deep foundation. The model test was performed on untreated soil and treated soil with 40 mm, 60 mm, 80 mm diameter stone column. The investigation focused on the influence of diameter of granular stone column. The tests were conducted on granular stone column having l/d ratio equal to 10. From the studies, the performance of smaller diameter stone column is superior to that of bigger diameter stone column. Due to its higher modulus of elasticity than that of soil, it absorbs more load than soil and reduces overall settlement.

Satish Barmade, Vinayak Kale, Mahesh R. Gadekar

Stability Analysis of Embankment on Stabilized Expansive Soil

In India, black cotton soil forms to be major soil deposits. They have been found to be the most problematic from engineering considerations since they exhibit swelling and shrinking when exposed to changes in moisture content. Vitrified tile sludge (VTS) is a waste material obtained during tile production and can be efficient in stabilizing embankments, soft soils, highway subgrade and other geotechnical application areas. High embankment slope has been stabilized using VTS as stabilizer. VTS was mixed by dry weight to soil with varying percentages of 0, 10, 20, 30 and 40% for conducting index properties, compaction characteristics, permeability, shear strength, consolidation and California bearing ratio tests. The experimental results indicate that the optimum VTS content was found to be 30%. The slope stability analysis was carried out for un-stabilized and stabilized embankment using Geo-Studio software. Slope stability is analysed for the high embankment of stabilized black cotton soil by taking its characteristics as input such as cohesion (c), angle of internal friction (ϕ) and maximum dry unit weight. The factor of safety of stabilized soil is more than minimum value as prescribed [1].

T. V. Sowmyashree, Muttana S. Balreddy

A Laboratory Study on the Mechanical Behaviour of Dredged Soil Admixed with Waste Rubber Tyre Powder and Cement

Due to the rapid development in automobile industry, the amount of tyre wastes has been increasing every year throughout the world. An attractive method to reduce the tyre waste produced is the use of recycled waste materials for civil engineering application, and also, it may be used as a stabilizer in soils so that it may help in improving the engineering properties of soft soil. Dredge material which belongs to soft soil deposits usually has low bearing capacity, high compressibility and undergoes settlement over a long period of time, hence cannot be used as a construction or foundation material. In this study, tyre rubber powder has been used to see its influence on the mechanical properties of dredged soil. Dredged soil was collected from the catchment of Dal Lake- Nishat. Various tests like specific gravity, gradation analysis, Atterberg’s limit, compaction tests, direct shear tests, unconfined compressive strength, California bearing ratio tests have been done in order to characterize and find the shear strength parameters. This study involves performing compaction test and UCS on the soil incorporated with rubber powder (passing 425µ) at varying percentages of 1.5, 3, 4.5, 6, 9, 12 and 15%. Also, to further improve the strength, cement at a constant percentage (2%) was added to rubberized soil and the effect on UCS characteristics at various curing periods of 3 and 7 days was analysed.

Rakshanda Showkat, B. A. Mir, K. M. N. Saquib Wani

Improvement of Strength Reinforced by Sugarcane Fibre

Soil is a base of structure, which supports the structure from beneath and distributes the load effectively. If the stability of the soil is not adequate, then failure of structure occurs in form of settlement, cracks, etc. Which can be prevented by soil reinforcement which is introduced in the field of geotechnical engineering by improving properties of soil. Which is the most popular techniques used for the improvement of poor soil. It causes significant improving in shear strength, bearing capacity, as well as economy. Many research has been conducted for stabilization of soil by using cementing, chemical materials, e.g. Fly ash, cement, Calcium chloride, etc. Today world is facing severe problem of disposal of agricultural waste. There are many natural fibre and synthetic fibre available in the market like Jute fibre, coconut fibre, palm fibre, sugar cane fibre and glass fibre, nylon fibre, polypropylene fibre, etc. Sugar cane fibre have chosen for soil stabilization in this study. Sugar cane fibre have been taken from sugarcane waste that is after extrusion of juice. In this experimental study, the fibre content has been taken 0.2%, 0.4% and 0.6% of the soil. After conducting series of experiment concluded that after mixing sugar cane fibre 0.6% of soil that is optimum fibre content, significant increment in angle of friction and decrement in the cohesion of soil is obtained.

Hasan M. Rangwala, Lavkush Agrawal, Vivek Makhecha, Ishan Gondaliya
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