Faculty Publications

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    Stabilization of lateritic soil using bio-enzyme
    (2008) Mithanthaya, I.R.; Ravishankar, A.U.
    Soil stabilization is a technique aimed at increasing or maintaining the stability of a soil mass, or otherwise improving its engineering properties. Various techniques are being used for stabilization of soil. Sub-base is an integral part of the road pavement structure. The main function of the sub-base is to provide a stress transmitting medium for spreading the surface wheel load in such a manner as to prevent shear and consolidated deformations. A number of researchers worked on characterizing variousus properties of the laterite soil and found that the following problems could be associated with the laterite: 1)In the majority of cases, the laterite doesn't satisfy conventional specifications for road construction materials especially road base. 2) The laterit undergoes property changes during construction; gradation being considered to be the most sensitive. To improve on the above deficiencies and consequently to improve on there field performance characteristics, laterites need to be stabilized. Bioenzyme - stabilization is a newer technique for strengthening the sub-base soil. The Bioenzyme alters the engineering properties of soil such as the capacity to bear loads. These enzymes are liquid additives, which act on the soil to reduce the voids between soil particles and minimize absorbed water in the soil for maximum compaction. The locally available laterite soil procured from the field is used to improve the strength and bearing capacity. One type of Bio-enzyme namely TerraZyme has been used for stabilization of laterite soil. In this study soil with variable enzyme dosages were tested for stabilization process and strength of the stabilized soil has been evaluated after curing period of one week, two weeks, three weeks and four weeks. The tests were carried out to determine the consistency limits, CBR, unconfined compressive strength and permeability of the soil specimens with and without enzyme for a curing period of one week to four weeks. The effect of enzyme on different percentages of sand blended laterite soil was also studied for the curing periods. The enzyme treated soil showed significant improvement in CBR (California bearing ratio) and UCS (Unconfined Compressive strength) with curing. © AES-Advanced Engineering Solutions.
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    Hydraulic and compaction characteristics of leachate-contaminated lateritic soil
    (2007) Nayak, S.; Sunil, B.M.; Shrihari, S.
    Large quantities of leachate-contaminated lateritic soil results from dump yards in the southwest coast of India. These dump yards receive large quantities of municipal solid waste which includes chemical, industrial and biomedical wastes. Large areas of land are currently being used for this purpose. An extensive laboratory testing program was carried out to determine the compaction characteristics and hydraulic conductivity of clean and contaminated lateritic soil. Batch tests were used to study the immediate effect of leachate contamination on the properties of lateritic soil. Contaminated specimens were prepared by mixing the lateritic soil with leachate in the amount of 5%, 10% and 20% by weight to vary the degree of contamination. The results indicated a small reduction in maximum dry density and an increase in hydraulic conductivity due to leachate-contamination. The change induced by chemical reaction in the microstructure of the soil was studied by scanning electron microscope before and after contamination of soil with leachate. The structure of the leachate contaminated soil sample appeared to be aggregated in scanning electron microscope analysis. The aggregated structure increases the effective pore space and thus increases the hydraulic conductivity. Fifty percent increase in hydraulic conductivity was observed for specimens prepared at standard Proctor density and mixed with 20% leachate. Compaction characteristics did not change much with the presence of leachate up to 10%. With 20% leachate the maximum dry density decreased slightly indicating excess leachate in the soil. However the changes are not significant. © 2007 Elsevier B.V. All rights reserved.
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    Characterization of porous friction course mixes for different Marshall compaction efforts
    (2009) Suresha, S.N.; George, V.; Ravi Shankar, A.U.R.
    Porous friction courses (PFCs) are mainly recommended as surface drainage layers on high-speed road-corridors and runway pavements. Permeability and sound attenuation characteristics are considered to be the indices for performance assessment of PFCs. One of the reasons for the loss of permeability in PFCs is densification under heavy traffic. But, resistance to ravelling too, is of main concern in the case of under-compacted PFCs. This paper summarises the details of laboratory investigation on the characterization of PFC mixes corresponding to four different gradations and two binder contents, for three levels of the Marshall compaction. The findings of the investigation suggest that the selection of the compaction level for PFC mix design should be based on the design traffic level, and the gradation selected. © 2009 Elsevier Ltd. All rights reserved.
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    Study of the properties of SCC with quarry dust
    (2009) Gowda, M.R.; Narasimhan, M.C.; Karisddappa; Rajeeva, S.V.
    Granite fines or rock dust is a by-product obtained during crushing of granite rocks and is also called quarry dust (QD). This paper deals with using quarry dust as an alternative to fine aggregate (FA) in SCC and reports the strength behaviour and hardened properties of such SCCs. Although in normal concretes, introducing QD increases the water demand, in SCC, it has been successfully used for increasing the deformability and passing ability of fresh concrete. Also, it was noted that by increasing the pouring heights of an SCC, the compressive strength and splitting tensile strength of concrete were unaffected.
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    Interactions Between Soils and Laboratory Simulated Electrolyte Solution
    (2010) Nayak, S.; Sunil, B.M.; Shrihari, S.; Sivapullaiah, P.V.
    To study the impact of salt water intrusion on two types of soils from west coast region of India were investigated in the laboratory. The key characteristics evaluated included Atterberg limits, compaction characteristics, hydraulic conductivity and chemical characteristics of selected soils. The sea at this coast receives effluent from different points and hence the characteristics change with time and locality. Therefore, to maintain uniform composition, 0.5 N sodium chloride solution (NaCl) was prepared in the laboratory and batch tests were used to determine the immediate effect on soils. Soil specimens were prepared by mixing the soils with 0.5 N NaCl in the increments of 0, 5, 10 and 20% by weight to vary the degree of contamination. Experimental results of soils mixed with 0.5 N NaCl showed that the maximum dry density increases and the optimum moisture content (OMC) decreases with increasing sodium chloride concentration. The study also revealed that the hydraulic conductivity of the soils tested increases with increase in sodium chloride concentration. The Atterberg limits of contaminated specimens show a remarkable change when compared with uncontaminated specimens. © 2010 Springer Science+Business Media B.V.
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    Geotechnical characteristics of lithomargic clay blended with marine clay as landfill liner material
    (CAFET INNOVA Technical Society cafetinnova@gmail.com 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2012) Allamaprabhu, K.; Sunil, B.M.; Nayak, S.; Fernandes, S.; Zafar, M.
    This paper reports a series of laboratory tests conducted on lithomargic clay (shedi soil), which is widespread over part of southwest coast of India, to assess whether it could be used as compacted clay liner for hydraulic barriers in engineered landfill. In order to assess the suitability of lithomarge as a barrier material, following tests such as index properties, compaction characteristics, hydraulic conductivity and unconfined compressive strength of the soil were conducted in the laboratory. From the studies, it is found that lithomargic soil is near to the recommended specifications for soils to be used as liner material. Suitable materials for soil liners are then obtained by blending different types of locally available soils to achieve the required low hydraulic conductivity and good strength. To achieve specifications for the liner material lithomargic clay is blended with 15% and 20% marine clay by weight of lithomargic clay. From standard compaction control, the blended soil shows hydraulic conductivity lower than the 1x10-7 cm/s. Acceptable zones (AZ) are constructed on the compaction plane to meet design objectives for hydraulic conductivity. It's strength properties show that the soil possesses higher strength than the recommended minimum strength of 200kPa, to support the overburden pressure imposed by the waste body. From the laboratory test results, it can be concluded that lithomargic clay blended with marine clay satisfies the requirements for a good soil liner material. © 2012 CAFET-INNOVA TECHNICAL SOCIETY.
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    Fatigue and Engineering Properties of Chemically Stabilized Soil for Pavements
    (Springer, 2013) Lekha, B.M.; Ravi Shankar, A.U.; Goutham, G.
    Soil stabilization is a technique to improve the weak soils and making them to meet certain requirements of the specific engineering projects. The type of soils available in Dakshina Kannada region of Karnataka State is laterite and Lithomarge clay. Its Plasticity Index is very high due to the presence of high percentage of silt and clay content. In the present investigation, an attempt is made to study the behaviour of laterite with and without adding chemicals. A chemical named Zycosoil, when added to water and mixed with soil alters its engineering properties that depend upon the type of the soil and dosage of chemical. These chemicals are liquid additives, which act on the soil to reduce the voids between soil particles and minimize adsorbed water in the soil for maximum compaction. In the present study, the effectiveness of Zycosoil in stabilizing the laterite soils of South Canara district is investigated through laboratory experiments. Various geotechnical properties are studied and correlations between different geotechnical properties and improvement in the soil properties with different percentages of chemical additions are derived. The important properties such as index properties, compaction characteristics, unconfined compressive strength parameters, California bearing ratio values and fatigue behaviour were studied. The results obtained indicate that there is an improvement in almost all properties with the addition of Zycosoil. © 2012 Indian Geotechnical Society.
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    Titanium foam with coarser cell size and wide range of porosity using different types of evaporative space holders through powder metallurgy route
    (Elsevier Ltd, 2014) Mondal, D.P.; Patel, M.; Das, S.; Jha, A.K.; Jain, H.; Gupta, G.; Arya, S.B.
    Ti-foams were made using different evaporative types of space holders such as acrowax and ammonium bicarbonate with a wide range of porosities (55-89%) through powder metallurgy technique. Cold compaction pressure was varied from 100 to 200. MPa in order to examine the effect of cold compaction pressures on the absolute porosities of the foams. The cell size, cell wall thickness and porosities of the foams were characterised as a function of cold compaction pressures and type of space holders. Empirical correlation has been established to predict foam porosities from compaction pressures and volume fraction of space holder. The sintered foams were found to be free from residue of the space holder. However, approximate 8-10% of titanium oxidized during sintering. The foam made with acrowax, as space holder attains slightly higher strength, modulus and energy absorption. © 2014 Elsevier Ltd.
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    Establishing relationships for strength characteristics of lateritic soils with varying silt fractions
    (CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2016) Kumar, A.; George, V.; Marathe, S.
    Design and construction of highway embankments constitute a major component of highway engineering science. Poor sub-grade strength, overloading due to traffic loads, and seismic vibrations can cause distress to pavement sub-grades and embankments. Inadequate compaction and poor sub soil drainage, in addition to low bearing strength of soils cause failure of embankments especially in submersible regions. The present study is focused on performing investigations on the engineering properties of lateritic and lithomargic soils and the effect of fines on soil strength. Tests such as California Bearing Ratio (CBR), tests for unconfined compressive strength (UCS), and tri-axial tests are carried to study the strength behavior of soil on addition of lithomargic soils. Additionally, the development of regressions will help field engineers in estimating the value of the CBR based on simple laboratory experiments such as Unconfined Compression strength test, and the Triaxial test. © 2016 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.
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    Influence of Drying Temperature on Three Soils Physical Properties
    (Springer International Publishing, 2016) Sunil, B.M.; Deepa, A.V.
    Changes in plasticity characteristics of three soils upon drying are examined in this paper. These changes are attributed to aggregation of particles. The key characteristic evaluated was the impact of drying temperature on the index properties, compaction characteristics and California bearing ratio. The study found the effect of drying strongly depended on soil type, mineralogy or presence of cementing agents. The observed changes are found to be permanent and the implications are that these changes may affect the field performance of test soils. © 2016, Springer International Publishing Switzerland.