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    Experimental Investigation of Black Cotton Soil Stabilized with Lime and Coconut Coir
    (Springer, 2018) Ravi Shankar, A.U.; Panditharadhya, B.J.; Karishekki, S.; Amulya, S.
    Expansive soil occurring above the water table undergo volume changes with change in moisture content. In expansive soils, increase in water table causes swelling–shrink behaviour which leads to cracks and differential settlement resulting in several damages to the pavements, canal beds and linings, foundations, buildings, etc. An attempt is made in this paper to study the effect of adding lime-coir fiber on geotechnical properties of black cotton soil. In the present study an effort is made to obtain the optimum dosage of lime for stabilization of black cotton soil abundantly available in Karnataka state of India. The study incorporates investigation of basic geotechnical properties like grain size distribution, specific gravity, consistency limits and engineering properties like Maximum Dry Density (MDD), Optimum Moisture Content (OMC), Unconfined Compressive Strength (UCS) and California Bearing Ratio (CBR). Swelling properties have been determined by conducting Free Swell Index (FSI) test. Durability of the soil is studied by conducting wet-dry cycle and freeze-thaw cycles (WD and FT tests). Fatigue test has been conducted to determine the fatigue life of treated and original soil. Further chemical analysis was conducted to determine the chemical composition of untreated and treated soil. The optimum dosage of lime obtained was 4%. The investigations were carried out to study the effect of addition of coir fibers which are obtained from local market to evaluate the extent of modification on MDD, OMC, UCS and CBR of the soil. Maximum improvement in UCS and CBR values are observed when 1% of coir are mixed with the soil. Soil stabilized with Lime-Coir fiber has shown better results when compared to soil stabilized with lime alone. It is concluded that the proportion of 1% coir fiber in a soil is the optimum percentage of materials having maximum soaked CBR value. Hence, this proportion may be economically used in road pavement and embankments. © Springer Nature Singapore Pte Ltd. 2018.
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    Durability Studies on the Lateritic Soil Stabilized with GGBS and Alkali Solutions
    (American Society of Civil Engineers (ASCE) onlinejls@asce.org 1801 Alexander Bell DriveGEO Reston VA 20191 Alabama, 2019) Amulya, S.; Ravi Shankar, A.U.; Panditharadhya, B.J.
    In order to use the locally available lateritic soil as a base course for pavement construction, the engineering properties of the soil need to be enhanced. Hence, the experimental investigation of the lateritic soil stabilized with the ground granulated blast furnace slag (GGBS) and combination of alkali solutions such as sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) has been conducted. The various parameters which affect the properties of the soil like binder (GGBS) content, sodium oxide (Na2O) dosage, silica modulus (Ms), and water to binder ratio (w/b) are considered. In the present investigation, the GGBS content of 25%, Na2O of 6%, Ms of 0.5, and w/b of 0.25 are chosen. The Atterberg's limits, standard and modified proctor compaction tests, unconfined compressive strength (UCS), and durability tests were conducted on the stabilized soil. The UCS of 28 days cured and stabilized samples at standard and modified proctor densities is showing 775% and 580% increase with respect to natural soil and 98% and 142% increase with respect to 0 days cured samples respectively. The chosen combination of soil mixture passes all 12 cycles of wetting and drying (WD) and freeze and thaw (FT) with weight loss of 5.2% and 1% at standard proctor density and 8% and 2.5% at modified proctor density respectively after 7 days of curing. © 2019 American Society of Civil Engineers.
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    Performance of Concrete Mix with Secondary Aluminium Dross as a Partial Replacement for Portland Pozzolana Cement
    (American Society of Civil Engineers (ASCE) onlinejls@asce.org 1801 Alexander Bell DriveGEO Reston VA 20191 Alabama, 2019) Panditharadhya, B.J.; Mulangi, R.H.; Ravi Shankar, A.U.; Amulya, S.
    The safety to our ecosystem can be assured by making use of many industrial wastes in a sustainable manner. Recycling and reutilisation of industrial waste and by-products is of high importance in cement and concrete industry. In view of rapid infrastructure growth, there is an emerging need for development of cementitious materials or fillers either to replace cement or fine aggregate for stable growth. One of such industrial wastes is secondary aluminium dross. In this paper, an attempt has been made to study the mechanical properties of concrete incorporated with secondary aluminium dross. Portland pozzolana cement has been partially replaced by secondary aluminium dross in various proportions like 5, 10, 15, and 20% to study the mechanical properties such as compressive strength, split tensile strength, flexural strength, water absorption. It is observed that up to 15% replacement of cement by secondary aluminium dross is giving better results comparable with the conventional concrete. Also, the increase in initial setting time is observed with increase in percentage replacement of aluminium dross in the concrete which can make it preferable in case of hot weather conditions wherein the concreting for the roads has to be done in an open environment. From the overall study, it can be concluded that the concrete incorporated with secondary aluminium dross can be used for making pavement quality concrete that can sustain low traffic volume or it can be considered for rural roads. © 2019 American Society of Civil Engineers.
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    Experimental Investigations on RBI Grade 81 Stabilized Lateritic Soil
    (Springer Science and Business Media Deutschland GmbH, 2021) Chethan, B.A.; Das, S.; Amulya, S.; Ravi Shankar, A.U.R.
    The effectiveness of the addition of RBI Grade 81 (stabilizer) (dosages of 2, 4, 6, and 8%) to stabilize the largely encountered lateritic soil during construction was investigated. Stabilized lateritic soil mixes were evaluated by conducting a series of experiments, viz., standard and modified compaction, unconfined compressive strength, and California bearing ratio at various curing periods. Mixes under both standard and modified compaction energies have shown the highest density at a 6% stabilizer dosage. A remarkable increase in unconfined compressive strength was observed for the specimens prepared at a 6% stabilizer dosage corresponding to the modified compaction density. An increase in the percentage of stabilizer has increased the California bearing ratio of treated mixes. Exorbitant increase in the soaked California bearing ratio values of the stabilized mixes was observed for higher dosages (6 and 8%). Hence, RBI Grade 81 amended lateritic soil mixes enhance the strength of the subgrade. © 2021, Springer Nature Singapore Pte Ltd.
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    Use of Stabilized Lateritic and Black Cotton Soils as a Base Course Replacing Conventional Granular Layer in Flexible Pavement
    (Springer, 2020) Amulya, S.; Ravi Shankar, A.U.
    The present work investigates the improved properties of lateritic and black cotton soils stabilized with ground granulated blast furnace slag (GGBFS) and alkali solutions. The alkali solution includes a mixture of sodium hydroxide and sodium silicate. The lateritic and black soils are treated with 30% GGBFS and the alkali solutions consisting of 6% Na2O having silica modulus (Ms) of 0.5, 1.0 and 1.5 at a constant water binder ratio of 0.25. The treated samples were air-cured for 0 (immediately after casting), 3, 7 and 28 days at ambient temperature. The treated lateritic soil with 0.5 and 1.0 Ms is found durable after 3, 7, and 28 days curing. Whereas, the treated BC soil found durable with Ms 0.5 at modified Proctor density after 28 days curing. The formation of calcium silicate hydrate and calcium aluminosilicate hydrate structures resulted in a remarkable improvement of compressive strength, flexure and fatigue life of treated soils due to dissolved calcium ions from GGBFS, silicate and aluminium ions from alkali solutions. The microstructure image of the durable soil sample shows the crystal orientation of particles. The design of high and low volume roads is proposed by replacing the conventional granular layer with the durable stabilized soil and stress–strain analysis is carried out using pavement analysis software. © 2020, Springer Nature Switzerland AG.
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    Replacement of Conventional Base Course with Stabilized Lateritic Soil Using Ground Granulated Blast Furnace Slag and Alkali Solution in the Flexible Pavement Construction
    (Springer, 2020) Amulya, S.; Ravi Shankar, A.U.
    The use of cement/chemical-treated base and sub-bases is widely recommended in the pavement construction. Therefore, this paper investigates the behaviour of stabilized lateritic soil as a base course in flexible pavement by replacing the granular base course. The lateritic soil was stabilized with 25% Ground Granulated Blast Furnace Slag (GGBFS) along with the alkali solutions such as sodium hydroxide and sodium silicate at a varying sodium oxide (Na2O) contents of 4, 5 and 6%, silica modulus (Ms, a ratio of silica to sodium oxide) of 0.5, 1.0 and 1.5 and a constant water binder ratio (w/b) of 0.25. The maximum compressive strengths of 5452 and 6593 kPa were achieved for a treated sample consisting of 6% Na2O and 1.0 Ms cured for 28 days at the light and heavy compactions, respectively, which is due to the formation of calcium silicate hydrates when calcium oxide-rich GGBFS reacts with water. Further with the curing period results in an increase in strength due to the formation of calcium alumino-silicate hydrates when GGBFS reacts with alkali solutions. The durability of the samples was evaluated by wetting–drying and freezing–thawing tests. The samples passing the required durability criteria were tested for flexural strength and fatigue life. Scanning electron microscope images showed closely packed crystal orientation indicating high strength. Low and high volume pavements were designed using stabilized soil as a base course, and the strains were evaluated using pavement analysis software. It is suggested that the conventional granular base layer can be replaced with the stabilized soil. © 2020, Indian Geotechnical Society.