Faculty Publications

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Influence of Integration of Iron Ore Tailings on the Physio-mechanical and Microstructure Properties of Fly Ash Based Coarse Aggregates
(ASTM International, 2023) Sharath, B.P.; Nikunj, P.; Das, B.B.
The goal of this experimental study is to produce fly ash (FA)-based coarse aggregates by adding iron ore tailings (IOT) to the FA-based precursor as an additional mix component. The involvement of different types of binders - influential factors of both pelletization and geopolymerization that govern the production of FA-based coarse aggregates - was experimentally designed by adopting Taguchi's experimental design. An evaluation was conducted utilizing response indexes at three curing periods to study the accumulation of all the influencing factors in the production process as well as on the engineering features of IOT admixed FA-based coarse aggregates. Aggregate impact and crushing values, individual pellet strength (IPS), and specific gravity and water absorption values were measured. According to experimental findings, IOT addition considerably affects the engineering characteristics of FA-based coarse aggregates. The heat resistance of the produced aggregates was found to be improved by the presence of different sodium oxide dosages and blending ratios (IOT:FA) based on analysis through scanning electron microscopy and thermogravimetric differential thermal analysis. The role of IOT in associative formation of calcium silicate hydrate is demonstrated by increasing calcium hydroxide, which supports increasing IPS values of produced aggregates. From the 1st to the 200th day of curing age, Fourier-transform infrared spectroscopy studies between the best- and worst-performing mixes showed two things: first, the emergence of new peaks with time, and second, the observation of major bands shifting to lower and higher wavenumbers, which was found to be directly correlated to the performance of the aggregates. © 2023 ASTM International. All rights reserved.
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.
Effect of Iron Ore and Copper Ore Tailings on Engineering Properties and Hydration Products of Sustainable Cement Mortar
(ASTM International, 2024) Sumukh, E.P.; Das, B.B.; Barbhuiya, S.
The prohibition of river sand mining has drawn the attention of researchers in finding practicable alternatives. In the approach of finding these alternatives, it is essential to ensure minimal or zero impairment to the ecological balance, which can be mainly attained by making use of industrial waste/byproducts. The wastes from the mining industry are the major contributors in causing impairment to the environment, and their influence on the stability of mortars on using as fine aggregates needs to be systematically investigated with the view of long-term performance concerns. Thus, the present study explores the applicability of mine tailings and finding the optimum dosage in cement mortars by investigating the engineering properties and microstructure development with the aid of qualitative and quantitative analysis associated with hydration products. The studies confirm that the increased consumption of portlandite for secondary hydration reactions followed by the additional formation of calcium silicate hydrate (CSH) and calcium aluminum silicate hydrate (CASH) phases in mine tailing-based mortars helped in achieving a quality microstructure. These additional formations of CSH and CASH phases are also confirmed through Fourier transform infrared spectroscopy by identifying the shift of Si-O-Si stretching vibration bands toward a lower wavenumber. The lowering of calcium/silicate atomic ratio and increased formation of mineralogical compounds related to CSH and CASH in x-ray diffraction patterns also confirms the same. Gismondine, chabazite, and hillebrandite are the additional phases formed and found to take part in refining the pore structure. This enhanced performance of mine tailing mortars was also verified with the aid of a modified Andreasen and Andersen particle packing model. The formation of high-quality microstructure is reflected in the hardened properties of optimized cement mortar in the proportion of 20 % for iron ore tailing and 30 % for copper ore tailing. © © 2024 by ASTM International.

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