Faculty Publications
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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 Influence of Geopolymerization Factors on Sustainable Production of Pelletized Fly Ash-Based Aggregates Admixed with Bentonite, Lime, and GGBS(American Society of Civil Engineers (ASCE), 2023) Sharath, B.P.; Snehal, K.; Das, B.B.; Barbhuiya, S.This experimental research investigates the influence of geopolymerization factors such as Na2O dosages, water and mineral admixture [bentonite (BT), burnt lime (BL), and ground granulated blast furnace slag (GGBS)] on physiomechanical properties of the pelletized fly ash (FA)-based aggregates. Taguchi's L9 orthogonal array was adopted to design the mixing ratios for three kinds of fly ash-based aggregates (in the combinations of FA-BT, FA-BL, and FA-GGBS). The degree of geopolymerization of the produced aggregates was characterized using thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and a scanning electron microscope (SEM). Most influential response indices in the production of pelletized aggregates were identified using gray relational analysis. The physiomechanical characteristics of the fly-ash aggregates were significantly improved by admixing BL than that of GGBS and BT. However, pelletization efficiency was seen to be superior for GGBS-substituted fly-ash aggregates. The quantified amount of hydration products, i.e., sodium alumino-silicate hydrate (N-A-S-H)/calcium alumino-silicate hydrate (C-A-S-H) for fly ash-based aggregates intensified on increasing Na2O and mineral admixture dosages. The results strongly suggest the existence of a linear relationship between the quantified amount of N-A-S-H/C-A-S-H and individual pellet strength of produced aggregate. The FTIR spectrum showed strong and broadened bands of Si-O terminal for all types of aggregates, representing the conversion of unreacted minerals to chains of aluminosilicate gel (geopolymerized hydration product). Further, it can also be inferred from gray relational analysis that among all other factors, Na2O content significantly impacted the engineering properties of produced fly ash-based aggregates. © 2023 American Society of Civil Engineers.Item COMPARISON OF MULTI CRITERION DECISION MAKING APPROACHES (MCDM) ON PRODUCED FLY ASH BASED PELLETIZED GEOPOLYMER COARSE AGGREGATES INTEGRATED WITH IRON ORE TAILINGS(Associated Cement Companies Ltd., 2023) Sharath, B.P.; Akhilesh Kumar, A.R.; Das, B.B.This research paper explores the implementation of multi-criteria decision-making approaches (MCDM) in the produced fly ash (FA) based pelletized geopolymer coarse aggregates integrated with iron ore tailings (IOT). Despite the fact that many techniques are available to aid the decision-making process, the decision makers (here the authors) are forced to go through the laborious task of selecting the appropriate MCDM method. It is because of the fact that each approach/method results in the attainment of different outcomes when applied to such specific scenario (in this case, the produced FA-based aggregates integrated with IOT). This research paper assesses three varied MCDM approaches, that are grey relation analysis (GRA), technique for order preference by similarity to ideal solution (TOPSIS) and desirability function approach (DFA), for the sixteen mixes involved in the production of FA-based aggregates integrated with IOT. These sixteen mixes were designed by taking into consideration of four experimental parameters that were Na2O and water content dosages, blend proportion of IOT and FA and SiO2/Na2O ratio, with the aid of Taguchi’s experimental methodology. The characteristics of the produced FA-based aggregates like aggregate impact value, aggregate crushing value, individual crushing strength of aggregates and water absorption served as inputs in the implementation of MCDM approaches on the produced FA-based aggregates integrated with IOT. The concluding remarks obtained by the implemented MCDM approaches proved to be effective in understanding the order of influence of experimental parameters taken under consideration for producing FA-based aggregates and among all, GRA stood as a relatively better approach in comparison with the other two approaches. © 2023, Associated Cement Companies Ltd.. All rights reserved.