Faculty Publications

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    Combined effect of marine environment and pH on the impedance of reinforced concrete studied by electrochemical impedance spectroscopy
    (Springer, 2019) Goudar, S.K.; Das, B.B.; Arya, S.
    In the present investigation, behavior of OPC and fly ash based concretes were assessed by electrochemical impedance spectroscopy (EIS) technique after exposing the samples to the marine environment in combination with five pH levels (1, 4, 7, 10, and 13). Three different dosages of fly ash (15, 25, and 35%) were used to produce fly ash based concretes. After 90 days of exposure to the aggressive environment, the OPC and fly ash based concretes were tested for impedance analysis and corrosion resistance by electrochemical studies. For the equivalent electrical circuit in EIS study, a total of four electrical circuits were tried for the possible best fit of obtained Nyquist plots. The equivalent electrical circuits proposed by previous researchers failed to provide the best fit for the obtained Nyquist plots. A new equivalent electrical circuit is being proposed in this study which will provide the possible best fit of Nyquist plots when the concrete is being exposed to acidic and alkaline marine environment. It is observed that the pH of the marine environment has a decisive influence on the impedance of reinforced concrete. As the acidity of marine environment reduces to pH 1, the impedance of OPC and fly ash based concrete reduced significantly due to the severe deterioration of concrete composites especially because of acid attack and Cl− ions migration. However, in the case of alkaline nature of the marine environment (pH 13), there was comparably less deterioration of concrete composites which reflected in higher impedance values. The higher dosage of fly ash addition has led to substantial improvement in concrete impedance and also lower corrosion rate. © Springer Nature Singapore Pte Ltd. 2019.
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    Characterization of Mechanical and Microstructural Properties of FA and GGBS-Based Geopolymer Mortar Cured in Ambient Condition
    (Springer, 2021) Prasanna, K.M.; Tamboli, S.; Das, B.B.
    Fly ash-based geopolymer mortars require heat curing to achieve its properties, which limits its practical application at ambient conditions. The present study was aimed to accomplish the need for application of fly ash-based geopolymers for practical viability without any heat curing by inclusion of ground-granulated blast furnace slag (GGBS). The results revealed that inclusion of GGBS as a partial replacement to fly ash (FA) in geopolymer mortar, which is cured in ambient curing condition, can be able to achieve required setting time and compressive strength. Amalgamation of GGBS with class FA as binder in geopolymerization lend a hand to attain compressive strength as well as setting time which is analogous to ordinary Portland cement (OPC). Microstructural properties were studied using scanning electron microscopy. © 2021, Springer Nature Singapore Pte Ltd.
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    Fly ash-reinforced poly(vinyl alcohol) composites
    (Elsevier, 2021) Anandhan, S.; SelvaKumar, S.; Patil, A.G.
    Fly ash (FA) is a waste residue and huge amounts of it have been produced from coal-fired power plants. As a result, it has become a serious issue and there is an urgent need to reduce its accretion as well as improve the safe disposal of FA as it has many toxic constituents including lead, arsenic, and chromium. In an effort to utilize FA, it has been widely used as filler for fabricating polymer composites to improve their performance. Recently, FA-incorporated polymers have received the attention of researchers and industries due to their remarkable properties, such as improved mechanical strength without sacrificing their elasticity, thermal, flame resistance, wettability, resistance to hydrolysis, and possessing excellent dynamic mechanical properties even at low temperatures. In comparison with conventional FA-based polymer composites, those based on surface-modified FA and nanostructured FA (NFA) exhibit superior mechanical and technical properties. The present article reviews various aspects of poly(vinyl alcohol)/FA-based composites. It also focuses on the effect of particle size reduction of FA on the physicochemical properties of poly(vinyl alcohol)/NFA composites. © 2022 Elsevier Inc. All rights reserved.
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    Performance of Geopolymer concrete mixes at elevated temperatures
    (2012) Kishanrao, M.P.; Narasimhan, M.C.
    Reducing the greenhouse gas emissions is the need of the hour. Five to eight percent of the world's man-made greenhouse gas emissions are from the Cement industry itself. It is an established fact that the green house gas emissions are reduced by 80% in Geopolymer concrete vis-a-vis the conventional Portland cement manufacturing, as it does not involve carbonate burns etc. Thus Geopolymer based Concrete is highly environment friendly and the same time it can be made a high-performance concrete. In the present study, fly ash, blast furnace slag and catalytic liquids have been used to prepare Geopolymer concrete mixes. This study is continued to investigate the behaviour of such Geopolymer concrete under high temperatures ranging from 100°C to 500°C. Cubes of size 100mm × 100mm × 100 mm are tested for their residual compressive strengths after subjecting them to these high temperatures. © 2012 IEEE.
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    Performance Evaluation of Fly-ash based Self-compacting geopolymer concrete mixes
    (Institute of Physics Publishing helen.craven@iop.org, 2019) Manjunath, R.; Ranganath, R.V.
    In this paper, an attempt has been made to develop Fly ash based self- compacting geopolymer concrete mixes with varying volume of pastes using conventionally available river sand as fine aggregate and crushed granite chips as coarse aggregate. These mixes were developed usingFly ash as the only major source material in the production of SCC mixes. Different amounts of Sodium silicate solutions, with specified amounts of Sodium Hydroxide flakes dissolved in them, are used as alkaline solutions. The total of four mixes were developed with varying volume of pastes in the range of 0.40 - 0.52 (within an interval of 0.04). These mixes were evaluated for their flow ability characteristics as per the relevant EFNARC guidelines. Further the mixes were evaluated for their mechanical properties in terms of compressive strength, splitting tensile strength and water absorption characteristics. Durability tests by means of subjecting to acidic and sulphate environments, along with their resistances to sustained elevated temperatures for a sustained period of 2 hours upto 800° C were carried out for all these mixes. The test results indicate better flow ability characteristics, along with their mechanical and durability properties. © 2019 IOP Publishing Ltd. All rights reserved.
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    Effect of Curing Methods on the Artificial Production of Fly Ash Aggregates
    (Springer Science and Business Media Deutschland GmbH, 2021) Shivaprasad, K.N.; Das, B.B.; Krishnadas, S.
    The experimental investigation, provides the results on the artificially produced fly ash aggregates through the pelletization process, is presented in this paper. NaOH and Na2SiO3 were used as alkali activator as a binder. The composition of alkaline solution is maintained as 5% of Na2O and SiO2/Na2O ratio of 0.3 with respect to weight of fly ash used. The detailed investigation is carried out by varying the water content to identify the optimum dosage of water in the alkaline solution in the fly ash pelletization. Further, different methods of curing were investigated to check for the suitable curing method for the production of fly ash aggregate produced. Optimum water content and suitable curing method will be identified through efficiency of pelletization and aggregate properties. Grey relation analysis is performed on the experimental test results to identify the influence of curing method on the produced aggregates. From these results, it is clearly understood that the curing method has significantly improved produced aggregates. © 2021, Springer Nature Singapore Pte Ltd.
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    Production of Artificial Aggregates Using Industrial By-Products Admixed with Mine Tailings—A Sustainable Solution
    (Springer Science and Business Media Deutschland GmbH, 2021) Sharath, B.P.; Das, B.B.
    This experimental cum research exploration is focused on the production of artificial aggregates with an adoption of pelletization technique. The influential factors for ascertaining the efficiency of the production process are nature of binding agent, required moisture content, process duration and dosage of alkali binder. Aggregates were produced in various combinations including the industrial by-products replaced partially by mine tailings with the addition of some percentages of lime. These produced aggregates were analysed for their engineering properties. It was observed that with the utilization of these mine tailings in this production of artificial aggregates have given an enhancement in the basic characteristic properties of the produced aggregates which are nearly comparable to that of natural aggregates. © 2021, Springer Nature Singapore Pte Ltd.
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    Investigation on Hybrid Polyester Composite Comprising of Sisal and Coir as a Reinforcement and Fly Ash as Filler
    (Springer Science and Business Media Deutschland GmbH, 2021) Darshan, M.L.; Biradar, S.; Ravishankar, K.S.
    The use of lignocellulosic fibers such as coir and sisal as reinforcements in thermoplastic and thermosetting resins for developing new material having property superior than the existing one. These biofibers have several advantages, such as good strength, flexibility, low densities, low cost, and biodegradability; over synthetic fibers, these natural fibers are made hydrophobic by 8% NaOH treatment. Alkali treatment increases wettability of fibers with resin and interfacial bond strength. This paper is highlighting about the preparation of hybrid composite and testing the prepared samples for various mechanical and tribological tests such as tensile, flexural, and slurry erosion tests conducted for coir/sisal-hybrid fibers with fly ash as a filler in unsaturated polyester resin. The obtained results are further justified by the SEM images of tested samples from different mechanical tests. This material has been used for automobile application and packing material, roofing material in construction technology. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
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    Compressive Strength of High Plastic Clay Stabilized with Fly Ash-Based Geopolymer and Its Synthesis Parameters
    (Springer Science and Business Media Deutschland GmbH, 2021) Neeraj Varma, N.; Kumar, T.; Thotakura, V.
    Geopolymerization is an effective technique for utilizing industrial solid waste material as stabilizing material. This paper studies the effect of class-F fly ash-based geopolymer on compressible strength characteristics of high plastic clay using unconfined compression strength (UCS) test. Sodium silicate and sodium hydroxide were used as alkali activators in proportions of 60:40, respectively. The fly ash content was varied by 0, 10, 20 and 30% by dry weight of soil, and alkali activator was varied by 5, 10 and 15% by dry weight of soil–fly ash mix. UCS tests were carried out on the specimens contaminated under controlled curing environment. Unconfined compression strength increased with increase in fly ash and liquid activator content. The maximum UCS value of 790 kPa observed at 30% of fly ash content under elevated temperature of 50 °C. The influence of Si/Al and Na/Al ratios on compressive strength of geopolymeric materials was also identified. Further, numerical analysis was carried out to check the significance of factors effecting the compressive strength of the material. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
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    Strength and Durability Properties of Alkali-Activated Fly Ash Earth Bricks
    (Springer Science and Business Media Deutschland GmbH, 2022) Vasavi, G.S.; Mourougane, R.; Pavan, G.S.
    This study explores the strength and durability characteristics of alkali-activated fly ash earth bricks. Two kinds of bricks were produced, one set of bricks with the use of manufactured sand or M-sand and another set without M-sand. Alkali activator which is a combination of laboratory-grade sodium silicate and 10 M sodium hydroxide in 1:1 mass ratio is used in the study. Soil classified as clayey sand with a clay content of 14% is selected for the project. The fly ash/soil ratio and alkali activator/fly ash ratios of 0.4 and 0.6, respectively, are employed in the current study. Activator was added to the soil and M-sand and fly ash mixture and mixed thoroughly. The moist mixture was then added into the brick-making machine and compacted into bricks of size 114 mm × 102 mm × 230 mm. The bricks were subjected to ambient curing until the day of testing. Wet and dry compressive strength tests, complete saturation, flexure test, and split tensile test were conducted on the bricks. It was found that the dry compressive strength of the bricks is in the range of 8 to 10 MPa, wet compressive strength is around 70% of dry compressive strength, water absorption is around 8–12%, and split tensile strength is in the range of 0.47–0.55 MPa and with flexural strength of 0.85–1.01 MPa. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.