Journal Articles
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884
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Item 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 LtdItem 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.Item 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.Item 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.