Browsing by Author "Shivaprasad, K.N."

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Determination of optimized geopolymerization factors on the properties of pelletized fly ash aggregates
(Elsevier Ltd, 2018) Shivaprasad, K.N.; Das, B.B.
This research investigates the effect of geopolymerization factors on the pelletization in the production of artificial fly ash aggregates. The proportion of pelletized fly ash aggregate mixes was designed through Taguchi's L9 orthogonal array. The properties of the aggregates produced from the optimal mixes were characterized according to the standard specifications. The effect of geopolymerization factors such as Na2O content, water content, and curing regime on the properties of the pelletized fly ash geopolymer aggregates was determined through response indices at the age of 14, 28 and 56 days. In addition, Grey relation based analysis was performed to identify the most critical parameter for optimization among three geopolymerization factors selected in this investigation, for the production of pelletized fly ash geopolymer aggregates. It is observed from the response indices and Grey relation results that the impact value of the aggregates and crushing strength of individual pellets is governed by heat curing and high water content at the age of 14 and 28 days. However, at the age of 56 days these response indices are significantly governed by the solution curing and high water content. It was also noted that the minimum Na2O content of 3.5–4.5% is adequate for the production of pelletized fly ash aggregates. © 2017 Elsevier Ltd
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. Â© 2021, Springer Nature Singapore Pte Ltd.
Effect of Duration of Heat Curing on the Artificially Produced Fly Ash Aggregates
(2018) Shivaprasad, K.N.; Das, B.B.
This paper presents the results of an experimental investigation on the production of artificial fly ash aggregates through the process of pelletization. The alkaline solutions like sodium silicate and sodium hydroxide was used to activate the fly ash. The alkaline solution contains 4.5% of Na2O, Si2O/Na2O ratio of 0.3 and 20% of water content with respect to mass of fly ash were used as binder in the production of fly ash geopolymer aggregates. The experiments were conducted by varying with different parameters. Curing of artificial fly ash aggregates was done with ambient temperature and heat curing (60 to 80 �C). Six levels of duration of heat curing were considered for this study. The optimum temperature and duration of curing is essential in geopolymerization reaction to achieve good characteristics of the produced aggregates. Grey relation analysis was performed to identify the effect of heat curing. Test results and grey relation analysis shows that the characteristics of the artificial produced fly ash aggregates has significantly improved with increase in temperature and duration of oven curing. � 2018 Institute of Physics Publishing. All rights reserved.
Effect of Duration of Heat Curing on the Artificially Produced Fly Ash Aggregates
(Institute of Physics Publishing helen.craven@iop.org, 2018) Shivaprasad, K.N.; Das, B.B.
This paper presents the results of an experimental investigation on the production of artificial fly ash aggregates through the process of pelletization. The alkaline solutions like sodium silicate and sodium hydroxide was used to activate the fly ash. The alkaline solution contains 4.5% of Na2O, Si2O/Na2O ratio of 0.3 and 20% of water content with respect to mass of fly ash were used as binder in the production of fly ash geopolymer aggregates. The experiments were conducted by varying with different parameters. Curing of artificial fly ash aggregates was done with ambient temperature and heat curing (60 to 80 Â°C). Six levels of duration of heat curing were considered for this study. The optimum temperature and duration of curing is essential in geopolymerization reaction to achieve good characteristics of the produced aggregates. Grey relation analysis was performed to identify the effect of heat curing. Test results and grey relation analysis shows that the characteristics of the artificial produced fly ash aggregates has significantly improved with increase in temperature and duration of oven curing. Â© 2018 Institute of Physics Publishing. All rights reserved.
Effect of various additives on the properties of fly ash based geopolymer mortar
(Springer, 2019) Mustafa, R.; Shivaprasad, K.N.; Das, B.B.
In the present study, setting time and variation in strength of fly ash based geopolymer mortar prepared from natural sand as fine aggregates. Blast furnace slag (GGBS), micro silica and lime dust used as additives to fly ash based geopolymer mortar at 5, 10 and 15% of weight of fly ash. Alkaline activator used in the present study is combination of sodium silicate solution and sodium hydroxide solution. Concentration of sodium hydroxide solution was maintained 10 M and sodium silicate to sodium hydroxide ratio was fixed as 2.5:1 by weight. From the test results, it is observed that setting time and compressive strength geopolymer samples were significantly influenced by the type of additive added in the preparation of the geopolymer mortar. © Springer Nature Singapore Pte Ltd. 2019.
Fast Setting Steel Fibre Geopolymer Mortar Cured Under Ambient Temperature
(Springer, 2021) Prasanna, K.M.; Theodose, I.; Shivaprasad, K.N.; Das, B.B.
Cement and cementitious materials are being used worldwide as the most popular multipurpose construction materials but the greenhouse gas such as carbon dioxide (CO2) produced during its manufacturing process creating a huge environmental hazard, thus efforts have been made for alternative binders. Geopolymer binder is new age binder alternative to ordinary Portland cement in infrastructure projects because it is produced from eco-friendly and industrial waste materials. This study was aimed to produce fast setting with ground-granulated blast-furnace slag (GGBS) in fly ash-based geopolymer mortar incorporated with steel fibres cured under ambient temperature. In this research, alkaline to binder ratio was varied from 0.5 to 0.8, crimped steel fibre are varied from 0.5 to 1.5% by total volume of binder and combination of fly ash (FA) and GGBS (100%:0%, 90%:10%, 80%:20%, 70%:30%, 60%:40% and 50%:50%) as binder were used for preparation of fibre geopolymer mortar. The tests conducted include stetting time and flowability of geopolymer mortar, compressive strength and microstructural characterisation of steel fibre geopolymer mortar. The tests for compressive strength were carried out on standard size of mortar samples at curing period of 3, 7 and 28 days. It is noted from the test results that increase in GGBS content setting times were decreased; however, the compressive strength of fly ash-based geopolymer mortar increased. The highest compressive strength at 28 days of curing period was found to be 69.5 MPa, which is obtained with content of 1% of steel fibres and alkaline to binder ratio of 0.6 with 50%:50% binder’s proportions. Further, it is observed that the incorporation of steel fibres in plain geopolymer mortar have enhanced the compressive strength and optimum dosage of fibres was found to be 1%. © 2021, Springer Nature Singapore Pte Ltd.
Influence of fineness of fly ash on compressive strength and microstructure of bottom ash admixed geopolymer mortar
(Associated Cement Companies Ltd., 2018) Shivaprasad, K.N.; Das, B.B.; Renjith, R.
Investigations were conducted to find out the suitability of bottom ash as a possible replacement to fine aggregates in geopolymer mortar. Experimental work was done to study the influence of fineness of fly ash (with three levels of Blaine's fineness, 2043 cm2/g, 2602 cm2/g and 3113 cm2/g on compressive strength and microstructure development of fly ash based geopolymer mortar with natural river sand and bottom ash as fine aggregates. three different water to solids ratios of 0.246, 0.349, and 0.443 were chosen for this study and the curing of the specimens was at ambient temperature (28 ± 3°c). compressive strength development for all eighteen mortar mixes was measured at 7, 14, 28 and 56 days. Further, the effect of fineness of fly ash on degree of polymerization, microstructure and properties of geopolymers was studied using Fourier transform Infrared Spectroscopy (FtIR) and Scanning Electron Microscopy (SEM). It was observed from the compressive strength of the geopolymer mortar that the degree of polymerization is gradual for both types of mortar. there is a continuous increase in the development of compressive strength noticed till the age of 56 days for both types of mortar, sand as well as bottom ash admixed. However, the increment of compressive strength for bottom ash found to be significantly less as compared to natural sand. Improvement in compressive strength due to fineness of fly ash were characterised by SEM and FtIR and it is revealed that with increase in fineness levels, the microstructure significantly enhanced the characteristics of geopolymer mortar. © 2018 Associated Cement Companies Ltd.. All rights reserved.
Influence of sample preparation techniques on microstructure and nano-mechanical properties of steel-concrete interface
(Elsevier Ltd, 2020) Goudar, S.K.; Das, B.B.; Arya, S.B.; Shivaprasad, K.N.
Interface between steel and concrete is characterized as highly porous and weakest region which influences both mechanical properties and durability of a reinforced concrete structure. The properties of the steel-concrete interface (SCI), especially the porous zone thickness are prime factors in predicting the time for corrosion initiation to corrosion cracking in service life prediction models. Measurement of porous zone thickness of reinforced concrete samples is sensitive to the sample preparation technique for microscopic observations. It is observed that there are hardly any research articles are available in the literature regarding the sample preparation technique of reinforced concrete sample for SCI analysis. In the present study, a detailed and stepwise sample preparation technique is proposed where there is minimal damage found to be observed to SCI. The major focus is on the speed of cutting tool that is being used for obtaining a relatively small size of sample from the bulk reinforced concrete member. The properties such as porous zone thickness and nano mechanical properties around the SCI were determined through scanning electron microscopy and nano-indentation, respectively. A significant variation in porous zone thickness around SCI was observed and measured value of average porous zone thickness is found to be approximately 1.8 times higher from high-speed cutting to low-speed. A similar kind of observation was noticed for nano mechanical properties. In addition to speed of cutting, there found to be other factors such as pressing force for specimen, duration of polishing and heating temperature has significant influence on interfacial properties. © 2020 Elsevier Ltd
Life cycle energy analysis of a metro station building envelope through computer based simulation
(Elsevier Ltd, 2018) Aneesh, N.R.; Shivaprasad, K.N.; Das, B.B.
This study focuses on the energy auditing of a metro terminal station building envelope which is located at a major city in south India. Embodied energy was calculated using the unit embodied energy values and by quantifying major energy consuming material used for the construction of a metro terminal station building. e-Quest, the energy simulation software was used for modelling the terminal station building and thereby calculated the yearly consumption of operational energy. Terminal station building is modelled with a detailed description of the building in e-Quest, which is being analysed with lighting, equipment's, thermostat settings, hourly scheduling of occupants and climatic data as the inputs to the model. In assessing the life cycle energy of the terminal station building, recurring energy and transportation energy were also calculated. In addition, this study discusses the comparative analysis on operational energy consumption for the same metro station model for three different climatic regions across India. Further, the present study on life cycle energy is compared with the life cycle energies of different types of buildings obtained from the literature, for an understanding of the energy usage demand per year per capita, between a public utility building, a commercial building and different types of residential buildings. © 2018 Elsevier Ltd
Mechanical properties of fiber-reinforced concrete using coal-bottom ash as replacement of fine aggregate
(Springer, 2019) Goudar, S.K.; Shivaprasad, K.N.; Das, B.B.
The present investigation aims to study the significance of coal coal-bottom ash as a partial replacement to natural river sand in fiber-reinforced concrete (FRC). Hooked-end steel fibers were used to produce fiber-reinforced concrete at a fiber content of 1.5% by volume concrete. About 30% of natural sand was replaced with coal coal-bottom ash to produce M30 grade concrete with a water–cement ratio of 0.45. The prolonged curing period has a positive effect on the coal, coal-bottom ash replaced concretes. There was a slight increment in the compressive strength of FRC because of inclusion of steel fibers. However, significant improvements were observed in flexural and split tensile strength of FRC due to the inclusion of steel fibers. The optimum content of coal, coal-bottom ash replacement to natural sand was found to be 20%. © Springer Nature Singapore Pte Ltd. 2019.
Pelletisation factors on the production of fly-ash aggregates and its performance in concrete
(ICE Publishing, 2023) Shivaprasad, K.N.; Das, B.B.; Sharath, B.P.
This research study investigates the factors associated with pelletisation in the production of fly-ash aggregates and its performance in concrete. To investigate this influence, experiments were carried out in different stages to explore the effect of factors responsible for pelletisation, which were designed through Taguchi’s experimental design. Additionally, the influence of each parameter on the engineering properties of the produced aggregates was determined using Grey relational analysis. Further, considering the optimised pelletisation factors of the laboratory-scale studies and with the help of an industrial-scale pelletiser, mass production of fly-ash aggregates was carried out and characterised for their engineering properties. The test results indicate that these aggregates are mainly governed by water content followed by the angle and speed of pelletizing disc. It is observed from the results that the engineering properties of aggregates produced on an industrial scale are found to be better than sintered aggregates and also comparable with that of natural aggregates except for water absorption. The properties of concrete produced with fly-ash aggregates, light weight sintered aggregates and natural aggregates were also studied. The results showed that properties of concrete produced with fly-ash aggregates are in good correlation with those of conventional concrete produced with natural aggregates. © 2023 ICE Publishing. All rights reserved.
Research on Setting Time, Compressive Strength and Microstructure of Fly Ash-Based Geopolymer Mixture Containing Slag
(Springer Science and Business Media Deutschland GmbH, 2023) Prasanna, K.M.; Sharath, B.P.; Choukade, H.; Shivaprasad, K.N.; Das, B.B.; Mahesh, G.
This study focusses on upgrading the fresh and hardened properties of fly ash-based geopolymer mix samples such as initial and final setting time, flow table test and compressive strength with the substitution of ground granulated blast furnace slag at varied percentage levels and with different alkali binder ratios. Substitution of slag in geopolymer mix samples is important so as to achieve fast setting characteristics in the product. For studying these effects on the microstructure of the product, scanning electron microscopy (SEM) with energy dispersive spectroscopy and Fourier transform infrared spectroscopy were conducted. The experimental outcomes stated that an increase in slag substitution has decreased the setting time and increased the compressive strength of geopolymer mix samples. SEM images have revealed the occurrence of a dense matrix with the slag substitution. FTIR results stated that shifting in wavenumbers of characteristic bands to lower numbers for varied slag substitution levels indicates a greater extent of geopolymerization. © 2022, The Author(s), under exclusive licence to Shiraz University.
Some Studies on Sustainable Utilization of Iron Ore Tailing (IOT) as Fine Aggregates in Fly Ash Based Geopolymer Mortar
(2018) Sharath, B.P.; Shivaprasad, K.N.; Athikkal, M.M.; Das, B.B.
This study presents the sustainable utilization potential of Iron Ore Tailings (IOT) as a replacement material against natural fine aggregates in the preparation of fly ash based geopolymer mortar. Low calcium fly ash is used as the source material and a mixture of sodium hydroxide and sodium silicate is used as the alkaline activator in the mix. Systematic studies such as setting times and compressive strength of the various mixes with different alkali binder ratio's were investigated in detail. It is to be noted that setting times of the mixes were found to be increasing with the increase in alkali binder ratio (0.4 to 0.8). Alkali binder ratio of 0.6 is found to be the optimum with respect to the compressive strength, irrespective of the type of fine aggregate. Scanning electron microscopy also reveals that microstructure of the fly ash based geopolymer mortar produced had a dense matrix with utilization of the Iron ore tailing. It can be concluded from the study that IOT is found to be a best alternative against the natural sand as a fine aggregate. � 2018 Institute of Physics Publishing. All rights reserved.
Some Studies on Sustainable Utilization of Iron Ore Tailing (IOT) as Fine Aggregates in Fly Ash Based Geopolymer Mortar
(Institute of Physics Publishing helen.craven@iop.org, 2018) Sharath, B.P.; Shivaprasad, K.N.; Athikkal, M.M.; Das, B.B.
This study presents the sustainable utilization potential of Iron Ore Tailings (IOT) as a replacement material against natural fine aggregates in the preparation of fly ash based geopolymer mortar. Low calcium fly ash is used as the source material and a mixture of sodium hydroxide and sodium silicate is used as the alkaline activator in the mix. Systematic studies such as setting times and compressive strength of the various mixes with different alkali binder ratio's were investigated in detail. It is to be noted that setting times of the mixes were found to be increasing with the increase in alkali binder ratio (0.4 to 0.8). Alkali binder ratio of 0.6 is found to be the optimum with respect to the compressive strength, irrespective of the type of fine aggregate. Scanning electron microscopy also reveals that microstructure of the fly ash based geopolymer mortar produced had a dense matrix with utilization of the Iron ore tailing. It can be concluded from the study that IOT is found to be a best alternative against the natural sand as a fine aggregate. Â© 2018 Institute of Physics Publishing. All rights reserved.
Study on mechanical properties and leaching of heavy metals in the artificially produced fly ash aggregates
(Springer, 2019) Roshan, M.; Shivaprasad, K.N.; Das, B.B.
The present study focusses on fly ash as an industrial by-product which can be utilised in the production of artificial lightweight aggregates using activator solution as a binder. Artificial aggregates in the form of pellets would be an alternative for the natural coarse aggregates which is currently being used in the construction industry. The production of pellets was done such that the water content in the pellets were fixed at 20% of the weight of fly ash, and the Na2O content in the pellets was varied between 4 and 7% of the weight of the pellets. The mechanical properties were studied such as specific gravity, particle-size distribution (sieve analysis), water absorption, crushing strength of individual pellets and aggregate impact value. Further, the leaching tests were carried out to estimate the leaching of metals such as iron, chromium and sodium from the pellets. The effect of different curing conditions such as ambient, heat and solution was also studied in this study. From the test results, the pellets size distribution was found to be well graded and specific gravity of pellets was found to be in the range from 1.88 to 1.96. There was an improvement in the mechanical properties of the artificially produced fly ash aggregates as the Na2O content increased in the alkaline solution. It was found that heat-cured pellets showed a significant advantage over solution and ambient-cured pellets in crushing strength. It was found that leaching of the heavy metals are decreased as the percentage of Na2O content increased, indicating that the addition of Na2O enhances the encapsulation of heavy metals. © Springer Nature Singapore Pte Ltd. 2019.
Study on the Production Factors in the Process of Production and Properties of Fly Ash-Based Coarse Aggregates
(Hindawi Limited, 2021) Shivaprasad, K.N.; Das, B.B.
An optimization study was carried out for the sustainable production of coarse aggregates from fly ash and alkaline solution, considering the combined effect of alkaline solution and production process. The trial mixes during the process of producing the artificial aggregates were designed through Taguchi's experimental design method. The combined effect of alkaline solution (geopolymerisation) and production process (pelletization factors) along with engineering properties of the produced coarse aggregates was evaluated using response indices at different curing ages. Furthermore, the influence of each individual factor of geopolymerisation and pelletization on the engineering properties was determined through grey relational analysis to identify the most influencing factors in the production of coarse aggregates. The results obtained from grey relational analysis indicate that the properties of produced aggregates are governed mostly by geopolymerisation. It is also observed that water content of 20% by mass of fly ash is found to be essential for the suitable production of coarse aggregates and factors such as Na2O content and curing regime improved the engineering properties. © 2021 K. N. Shivaprasad and Bibhuti Bhusan Das.