Thyagaraj T.

Thyagaraj T.
Indian Institute of Technology Madras | IIT Madras · Department of Civil Engineering

PhD, MS (Engg.) IISc, Bangalore, India

About

76
Publications
11,294
Reads
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839
Citations
Additional affiliations
March 2020 - present
Indian Institute of Technology Madras
Position
  • Professor (Full)
July 2015 - March 2020
Indian Institute of Technology Madras
Position
  • Professor (Associate)
August 2008 - July 2015
Indian Institute of Technology Madras
Position
  • Professor (Assistant)

Publications

Publications (76)
Article
Landfill liners located in the active zone are subjected to hydraulic and volumetric changes with time after their installation due to wet–dry (W–D) cycles. Drying results in the formation of desiccation cracks which increases the hydraulic conductivity, whereas the swelling aids in the closure of cracks. Recently, the clay–sand mixtures have been...
Article
Class C fly ash, a byproduct of thermal power plants, is often preferred for the stabilisation of expansive soils. However, improper optimisation of the stabiliser may lead to the premature failure of treated soils during wet–dry cycles. This study demonstrates the volume change behaviour of fly ash-stabilised expansive soils subjected to wet– dry...
Article
Full-text available
X-ray computed tomography (X-ray CT) in tandem with mercury intrusion porosimetry (MIP) has gained importance among researchers for examining the internal structure of geomaterials owing to the wide scale of coverage. The success of the X-ray CT lies in the proper segmentation of the acquired images during image processing. This study proposes a no...
Chapter
Expansive soils are mostly found in semi-arid and arid regions, and these soils suffer significant volume change when exposed to seasonal moisture fluctuations. Further, this volume change may cause extensive damages to the engineering structures and also the cost of damages increases every year. Practicing geotechnical engineers used different tre...
Article
Stabilization of soil for grounding purposes has been performed by adding different wt% of lime. Electrical breakdown measurements under lightning impulse voltage showed a reduction in breakdown voltage and the time to breakdown with increment in the lime content in the soil. These parameters also increased with curing period for all concentrations...
Article
The purpose of this paper is to understand the shrinkage behaviour of low plasticity soil, which is prevalent in Warangal, India. In this study, the shrinkage mechanism and behaviour with suction variation are characterised and described using simple and reliable experimental approaches. The findings concern the changes in suction, water content, a...
Chapter
Compacted clay liners (CCLs) are widely used as hydraulic barriers below the leachate collection systems of municipal solid waste (MSW) landfills as they reduce the rate of contaminant migration by advection owing to their low hydraulic conductivity and molecular diffusion. The main requirement of liner materials is to minimize the pollutant migrat...
Article
This research investigates the shrinkage behaviour of clay specimens subjected to different hydraulic paths. The volume change and microstructure of desiccated clay specimen directly dried from reconstituted slurry and compacted states, and the desiccated clay specimens obtained by subjecting the as-compacted clay specimen to cyclic wetting and dry...
Chapter
Expansive soils in the field are subjected to swelling and shrinkage due to seasonal moisture variations. Most of the previous studies on swell-shrink were carried out by direct mixing of stabilizer with soil and very few studies have been carried out on swell-shrink behaviour of expansive soil stabilized through permeation. Hence, in the present s...
Article
The shrinkage of soil induced by cyclic moisture variation from the post-compaction state needs to be addressed for understanding its long-term performance. The soil shrinkage curve is modeled to characterize the loss of moisture and the associated soil volume change from the initially saturated state to zero volume change phase. The volume change...
Chapter
Clay liners are integral part of both hazardous and municipal waste landfills that prevent leachate from percolating into the soil beneath and polluting it. Hence, the compacted soils must have very low hydraulic conductivity (<10–7 cm/s) to act as effective clay liners. Locally available red soil may be used as a liner material as it satisfies the...
Article
Desiccation cracks in compacted clay liners act as preferential flow paths and affect the hydraulic response during initial stage of wetting. This paper investigates the effect of initial hydraulic gradient on swell, infiltration and hydraulic conductivity during wetting of desiccated expansive soil specimens in oedometric-infiltrometer test set-up...
Article
The addition of cement for stabilization of expansive soils is one of the most commonly used methods. As with every calcium-based stabilizer, the time delay between the physical mixing of the stabilizer and compaction plays an important role in achieving the desired results after stabilization. However, a clear insight on the determination of optim...
Article
Full-text available
Clay liners are provided in waste landfills to prevent the leachate from percolating into underlying soil and ground water and polluting it. Hence, soils used as landfill liners must possess low hydraulic conductivity (< 10 ⁻⁷ cm/s). In the initial as-compacted state, liners satisfy this design criterion. However, in the field, liners are subjected...
Chapter
This paper brings out the effect of jute geotextile reinforcement on the load-bearing capacity of sand bed in both planar and geocell forms. A series of laboratory model tests were conducted using a 150 mm diameter (D) circular footing in a steel tank of 900 mm × 900 mm × 800 mm size. For the model tests, the relative density (Rd) of sand was maint...
Article
Physico-chemical interactions and alternate wetting and drying process have marked influence on the swell–shrink and hydraulic behaviour of compacted expansive soils used in various engineering applications. The microstructural, shrinkage cracks pattern and hydraulic behaviour of compacted expansive soils get altered due to the interactions with le...
Article
Swell potential and pressure of expansive soils are conventionally determined using an oedometer apparatus. The specimens are commonly saturated by submerging in water under a seating pressure. Generally, the test takes a long time, as the saturation process is slow. This article presents an improved saturation method by back pressure application i...
Article
In-situ deep stabilization of expansive soil deposits is commonly carried out using lime piles and lime slurry injection. Recent research demonstrated the stabilization of expansive soils using lime column technique, and more recently the lime precipitation technique has emerged as the viable choice for stabilization of expansive soils. Comparison...
Conference Paper
Clay liners are provided in waste landfills to prevent the leachate from percolating into underlying soil and ground water and polluting it. Hence, soils used as landfill liners must possess low hydraulic conductivity (< 10-7 cm/s). In the initial as-compacted state, liners satisfy this design criterion. However, in the field, liners are subjected...
Article
Application of lime as an additive for controlling the volume change behavior and improving the strength of expansive soils has been in use over several decades. However, the contamination of lime-treated expansive soil with sulfate always results in the deterioration of treated expansive soil. Therefore, this paper highlights the effect of sodium...
Article
Compacted clays are used as barriers in landfills mainly due to their low hydraulic conductivity and self healing properties. These clays are subjected to moisture fluctuations and simultaneously exposed to leachates. Besides swelling, the shrinkage and cracks developed during drying get altered due to their exposure to contaminants and control the...
Conference Paper
Alternate wetting and drying of soils arise as a result of seasonal moisture fluctuations which in turn lead to the volume change in soils. An increase in volume caused by an intake of water is termed as swelling, and a reduction in volume occurring due to loss of water is defined as shrinkage. Shrinkage poses a much more serious problem than the s...
Conference Paper
This paper presents a comparative study of stabilization of expansive soil using lime pile and lime precipitation technique. Lime precipitation was carried out by sequential permeation of calcium chloride (CaCl2) and sodium hydroxide (NaOH) solutions through a central hole in the compacted expansive clay. Similarly, lime pile was installed in a cen...
Article
Even though the effectiveness of sulfate-resistant cement (SRC) in stabilizing the high sulfate-bearing expansive soils is proven, its effectiveness in controlling the volume change of expansive soils when exposed to external sulfate contaminants is not known. The physico-chemical and index properties provide basic insight into the volume change be...
Article
Full-text available
This paper evaluates the optimum geometrical parameters of jute geotextile reinforcement for the load-bearing capacity based on the laboratory model tests carried out on 50, 100 and 150 mm diameter (D) circular footings resting on sand bed. These footing sizes were obtained using a scaling down factor of 4 for the prototype foundations so as to obt...
Article
Lime stabilization is an age-old technique for controlling the swell-shrink characteristics of the expansive soil. However, the presence of sulphate in the expansive soils renders the lime stabilization ineffective due to the formation of detrimental compounds – ettringite and thaumasite. The formation of these detrimental compounds can be countera...
Conference Paper
Swelling and shrinkage of expansive soils raise concern over their performance for various geotechnical and geoenvironmental engineering applications such as top and bottom liners of landfills.Swelling results in heaving of expansive soil whereas the shrinkage results in the formation of desiccation cracks. To overcome these volume changes in the e...
Article
In the present study, the cyclic triaxial tests and resonant column (RC) tests were carried out, to study the effect of frequency on reconstituted marine clay saturated with distilled water and NaCl solutions. Slurry consolidated samples were prepared at 50 kPa vertical stress. Samples were isotropically consolidated at three different effective co...
Conference Paper
Deep soil mixing is widely used technique for stabilizing thick deposits of soft clays. A laboratory trial was carried out to extend its application for stabilizing the expansive soils at high water content. Lime was used as a stabilizing agent, and in addition to that pond ash was mixed at proportions of 10%, 20% and 30% based on dry weight basis....
Conference Paper
It is well demonstrated in the literature that the addition of lime or sulfate resistant cement to the expansive soil effectively controls the swell potential and increases the unconfined compressive strength of stabilized expansive soil due to both soil modification and pozzolanic reactions. Also, the rapid industrialization has increased the chan...
Article
Full-text available
Compacted expansive soils undergo large volumetric changes during wet–dry cycles owing to the seasonal moisture fluctuations, and during drying the shrinkage is accompanied with the desiccation cracks. This paper presents the shrinkage behaviour of compacted expansive soil specimen, under a vertical stress of 12.5 kPa, in terms of void ratio–water...
Chapter
Compacted expansive soils are widely used as engineered barriers in waste contaminant applications like landfills, brine ponds, and nuclear waste disposal sites. These liners are designed for very low hydraulic conductivity (<1 × 10⁻⁷ cm/s). Percolation of chemical waste or leachate results in physicochemical changes in compacted expansive soils wh...
Chapter
Lime is the most commonly used chemical admixture for the treatment of the expansive soils. But the intrusion of sulfate contaminant into the lime treated soil will always results in deterioration of the treated soil. The intrusion of sulfate occurs through acid rains, effluent from tannery industries or mine wastes, intrusion of sea water, constru...
Book
The book comprises select proceedings of the 2016 annual conference of the Indian Geotechnical Society (IGC 2016), with technical papers on the theme “Ground Improvement and Geosynthetics”. The papers cover a wide range of topics, including chemical modification using admixtures, microbial-induced carbonate precipitation, geopolymers, fly ash and o...
Conference Paper
In the present study an attempt was made to stabilize the thick deposits of expansive soil using Deep Soil Mixing (DSM) technique. The strength and volume change characteristics were studied through unconfined compressive strength and swell test on 28 days cured samples. From the experimental study it was observed that with the addition of lime (4%...
Article
This paper presents a case study of a two-storey building in Oragadam, near Chennai (India), which has undergone distress due to the presence of expansive soil. Undulations in the floors, cracks in partition walls and non-uniform heave in the pavement are some of the failure patterns noticed in and around the structure. Undisturbed soil samples wer...
Conference Paper
The effect of pore fluid chemistry on the cyclic behaviour of fine grained soil is studied by performing strain controlled undrained cyclic triaxial tests on reconstituted marine clay with 0.4 M sodium chloride solution and distilled water. Specimens using different pore fluids were prepared by slurry consolidation method at vertical stress of 50 k...
Article
The volume change during drying of compacted expansive soils occur in the form of reduction in overall volume and development of cracks. Accurate determination of volume of shrunken soil specimens becomes essential to understand the shrinkage behaviour of compacted expansive soils. Mercury displacement method available for the bulk volume measureme...
Chapter
Physico-chemical interactions play a key role in understanding the behaviour of clay soils in wide range of geotechnical and geoenvironmental engineering applications. Its significance on the behaviour of clay soils reconstituted from slurries has been well demonstrated in the literature. Compacted soils and natural soil deposits which are unsatura...
Article
Physico-chemical effects assume significance in geoenvironmental engineering applications where compacted soils and natural soil deposits interact with chemical contaminants. The physico-chemical interactions occur at the microstructural level and affect the macrostructure and thus the volume change behaviour. This paper reveals the physico-chemica...
Article
The present study examines the relevance of placement conditions on the behaviour of polypropylene fiber rein- forced bentonite. The laboratory testing program includes conducting standard and modified Proctor compaction tests, tracing shrinkage behaviour, performing hydraulic conductivity and unconfined compression strength tests on both unreinfor...
Article
Physico-chemical effects have a significant impact on the behavior of clay barriers due to the interactions between the pore fluid and clay particles, and they pose a great challenge because the efficiency of clay barriers and cover systems may be altered. Therefore, this paper highlights the effect of physico-chemical factors on shrinkage behavior...
Article
The phenomenon of collapse assumes significance in the geotechnical engineering applications such as earth dams and highway and railway embankments as the compacted soils in these applications are susceptible to wetting-induced failures. Therefore, the present study focuses to understand the influence of placement conditions and vertical stress on...
Article
In geoenvironmental engineering applications, the compacted fills often come in contact with hazardous chemical contaminants and are subjected to physico-chemical changes. These changes alter the mechanical behaviour of compacted soils due to the physico-chemical interactions at the clay particle level, which are reflected as a variation in the yie...
Article
Full-text available
Coal ash is a by-product produced from the thermal power plants. It is characterized with low unit weight, high shear strength and low compressibility and finds a major application as an alternate material in the geotechnical engineering applications. However, some coal ash fills are susceptible to wetting-induced collapse due to the loss of capill...
Article
Coal ash is a by-product produced from the thermal power plants. It is characterized with low unit weight, high shear strength and low compressibility and f inds a major application as an alternate material in the geotechnical engineering applications. However, some coal ash fills are susceptible to wetting-induced collapse due to the loss of capil...
Article
Sequential permeation of calcium chloride and sodium hydroxide solutions into the soil mass leads to the formation of lime in the in-situ soil mass owing to chemical reactions. Previous studies have demonstrated that the lime precipitation modifies the expansive soil properties both by lime modification and pozzolanic reactions. However, the indepe...
Article
The experimental results of the present study on compacted expansive clay illustrate that matric suction increases with the increase in pore fluid osmotic suction due to changes in soil structure. Scanning electron micrographs show that particle stacking (aggregations) increases with increase in pore fluid osmotic suction and cation valence due to...
Article
The experimental results of the present study on compacted expansive clay illustrate that matric suction increases with the increase in pore fluid osmotic suction due to changes in soil structure. Scanning electron micrographs show that particle stacking (aggregations) increases with increase in pore fluid osmotic suction and cation valence due to...
Conference Paper
Full-text available
The presence of montmorillonite and kaolinite minerals in the collapsible soils make them susceptible to physico-chemical changes. Therefore it becomes essential to understand the physico-chemical effects on the collapse behaviour of compacted clay soil. This paper brings out the effect of osmotic gradients on the collapse behaviour of compacted re...
Article
Sequential permeation of calcium chloride and sodium hydroxide solutions into the soil mass leads to the formation of lime in the in-situ soil mass owing to chemical reactions. Previous studies have demonstrated that the lime precipitation modifies the expansive soil properties both by lime modification and pozzolanic reactions. However, the indepe...
Article
The present investigation examines the efficiency of an in situ lime precipitation technique in stabilizing expansive soil through laboratory-scale model tests. Expansive soil was compacted in a cylindrical mold and sequentially permeated with CaCl2 and NaOH solutions into the expansive soil through a central hole filled with coarse sand. Successiv...
Article
Previous investigation showed that sequential mixing of calcium chloride and sodium hydroxide solutions with an expansive soil resulted in lime precipitation in the soil mass, which controlled the swelling potentials and increased the unconfined compressive strength of treated specimens through strong modification and pozzolanic reactions. However,...
Article
Depending on the relative chemical concentrations of clay pore water and landfill leachate, three osmotic flow scenarios may be anticipated to dissipate the osmotic suction gradient: outward osmotic flow, inward osmotic flow and no (osmotic) flow. This study examines the volume change behaviour of clay subjected to all osmotic flow conditions. Resu...
Article
Full-text available
Compacted expansive clays swell due to crystalline swelling and osmotic/double layer swelling mechanisms. Crystalline swelling is driven by adsorption of water molecules at clay particle surfaces that occurs at inter-layer separations of 10–22 Å. Diffuse double layer swelling occurs at inter-layer separations >22 Å. The tendency of compacted clay t...
Article
Full-text available
Lime stabilization prevails to be the most widely adopted in situ stabilization method for controlling the swell-shrink potentials of expansive soils despite construction difficulties and its ineffectiveness in certain conditions. In addition to the in situ stabilization methods presently practiced, it is theoretically possible to facilitate in sit...
Article
This paper examines the efficiency of in-situ stabilization of expansive soil by lime slurry technique in desiccated state through laboratory and field experimental studies. The laboratory and field studies consists of permeating 34% hydrated lime slurry into the desiccated soil through vertical holes and measuring the physico-chemical, index and e...
Article
Full-text available
Compacted clay soils are used as barriers in geoenvironmental engineering applications and are likely to be exposed to salinization and desalinization cycles during life of the facility. Changes in pore fluid composition from salinization and desalinization cycles induce osmotic suction gradients between soil–water and reservoir (example, landfill/...
Article
Full-text available
Unsaturated clays are subject to osmotic suction gradients in geoenvironmental engineering applications and it therefore becomes important to understand the effect of these chemical concentration gradients on soil-water characteristic curves (SWCCs). This paper brings out the influence of induced osmotic suction gradient on the wetting SWCCs of com...
Article
Full-text available
Osmotic suction arises in clay soils due to the presence of dissolved salts in soil water. Variations in dissolved salt concentration of soil water impact the osmotic suction balance between soil water (of clay soil specimens) and external reservoir that gets adjusted through diffusion of salts and osmotic flow of water molecules. Available theoret...
Article
The present study examines the effect of inflow of sodium chloride solutions on the swell-compression behaviour of compacted expansive clays under a range of external loads. Inflow of sodium chloride solutions reduced the swell magnitudes and pressures and even caused the compacted clay specimens to experience compressive strains in oedometer tests...
Article
Compacted clay liners in landfills and brine ponds are subject to chemical concentration gradients between the soil water in the clay and the reservoir solution. Soil water is the solution residing in soil pores that is chemically composed of water $(H_2O)$ molecules and dissolved salts molecules (ISSS, 1976). These differences in salt concentratio...
Article
Full-text available
Lime slurry and lime pile techniques are viable choices for in-situ stabilisation of expansive soil deposits. This paper reports the results of a laboratory study on in-situ chemical stabilisation of an expansive soil that permeated lime slurry through an artificially desiccated expansive soil specimen. The soil was desiccated in the laboratory to...
Article
Total suction of unsaturated soils is contributed by matric and osmotic suctions. Matric suction arises from capillary actions in the soil structure and varies with changes in moisture content of the soil. Pore fluid osmotic suction is related to the dissolved salt content in soil water (soil water salinity) and increases with pore water salinity....

Projects

Projects (2)
Project
To understand how changes in soil suction impact the engineering behaviour of soils
Project
to understand the mechanism of sulphate contamination on treated expansive soils