Faculty Publications

Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736

Publications by NITK Faculty

Browse

Author: search.filters.author.Das, B.B.Subject: search.filters.subject.Curing

Search Results

Now showing 1 - 9 of 9
  • No Thumbnail Available
    Item
    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.
  • No Thumbnail Available
    Item
    Automation of Curing Using Prefabricated Sensors
    (Springer Science and Business Media Deutschland GmbH, 2021) Agarwalla, A.; Das, B.B.
    Curing is one of the universal phenomena followed after casting and finishing of concrete over an extended period of time, which helps to develop the compressive strength and durability by maintaining an optimum moisture and temperature condition. It keeps the concrete hydrated, restricts volumetric shrinkage, provides resistance to abrasion, freezing and thawing. There are many ways to cure concrete but, in this article, discussion will be on automation of curing using IoT and moisture sensors and relays which will likely replicate the lab condition on site by maintaining constant moisture content in concrete by supplying required amount of water. Generally, on site the curing process is carried out for 6–7 days once or twice a day at a large interval as a result of which the free moisture content falls and the rate of hydration decreases. It results in poor compressive strength and durability compared with laboratory samples because the 7 days compressive strength is not achieved which is more important than that of 28 days compressive strength which is successfully achieved in the lab. Various technologies used in this article will help in real-time monitoring of concrete condition with ease which will further be beneficial for the construction industry. This paper will cover how these technologies are integrated to automate the whole process, and its effect on compressive strength of concrete for which a consistent mix of M20, M25, M30 was prepared to compare the result of strength of concrete at 3, 7 and 28 days of curing in three different conditions, giving the strength of in-situ automatically cured concrete sample similar to that of laboratory cured concrete sample and an increase in 16.09% of compressive strength was observed with respect to concrete cured manually in site conditions. © 2021, Springer Nature Singapore Pte Ltd.
  • No Thumbnail Available
    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 Ltd
  • No Thumbnail Available
    Item
    Mechanical and permeability properties of hybrid fibre reinforced porous concrete
    (Associated Cement Companies Ltd., 2019) Snehal, K.; Das, B.B.
    Experimental investigation was carried out to determine the enhancement of compressive strength, flexural strength and abrasion resistance along with water permeability of porous concrete introduced with hybrid fibres (consists of equal proportion of steel, polypropylene and glass) and with two different sizes of coarse aggregate. The varying parameters in the preparation of porous concrete mix were coarse aggregate of two sizes, i.e., 6 mm and 12 mm and five different percentages of hybrid fibres (0.25 - 0.65 with an increment of 0.1). Compressive strength and flexural strength were measured at the end of two curing periods (7 and 28 days) whereas water permeability and abrasion test values were measured at the end of 28 days of curing. From the experimental findings, it is observed that compressive strength and flexural strength values increase with decrease in the size of the aggregate for control as well as fibre reinforced porous concrete. However, with respect to the measured values of permeability, it is found that with increase in size of coarse aggregates, permeability values also increases. For 28 days samples it is observed that 0.35% addition of hybrid fibres to porous concrete found to be optimum and it improved the compressive strength values by 20.24% and 19.06% for coarse aggregate sizes of 6mm and 12mm, respectively as compared to porous control concrete (without addition of hybrid fibres). Whereas, maximum flexural strength was obtained at 0.45% of addition of hybrid fibres and 31.6% (6mm coarse aggregate) increment and 24.26% (12mm coarse aggregate) increment were noticed as compared to porous control concrete. The best values for permeability were found at 0.35% of hybrid fibres and 12 mm coarse aggregate combination, whereas for abrasion resistance it was at 0.35% of hybrid fibres and 6mm coarse aggregate combination. © 2019 Associated Cement Companies Ltd.. All rights reserved.
  • No Thumbnail Available
    Item
    Microstructural study of steel-concrete interface and its influence on bond strength of reinforced concrete
    (ASTM International, 2019) Goudar, S.K.; Das, B.B.; Arya, S.B.
    In this investigation, the variations in steel-concrete interface (SCI) properties, such as porous zone thickness and calcium hydroxide content around the reinforcing steel, were studied with respect to curing time. Three kinds of commercially used cements, ordinary portland cement (OPC), portland pozzolana cement (PPC), and portland slag cement (PSC), were used, and their significance regarding SCI properties was investigated. A reliable thresholding grayscale-based technique was used to determine the porous zone thickness at the SCI. The properties of SCI were found to be quite influenced by the curing period. The PSC concrete showed significant reduction in mean porous zone thickness at SCI compared with OPC and PPC concrete after 90 days of curing. The reduction in mean porous zone thickness can be considered one of the many influencing factors that resulted in increased ultimate bond strength at 90 days of curing. Also, the variation in calcium hydroxide content from the SCI toward the bulk concrete was examined with a scanning electron microscope empowered with energy-dispersive spectroscopy. The findings indicate a gradual decrease in calcium hydroxide content away from the steel surface toward the bulk concrete. The prolonged curing resulted in a slightly higher reduction of calcium hydroxide content around the SCI for PPC and PSC concrete because of the pozzolanic reactions. Higher reduction of calcium hydroxide content around the SCI for PPC and PSC concrete is predicted to be the reason for improved ultimate bond strength after prolonged curing. © 2019 by ASTM International.
  • No Thumbnail Available
    Item
    Ferrochrome ash – Its usage potential in alkali activated slag mortars
    (Elsevier Ltd, 2020) Kumar, K.B.; Yaragal, S.C.; Das, B.B.
    This study is an attempt to develop a sustainable construction material, i.e., alkali activated slag (AAS) in combination with ferrochrome ash (FCA) as a replacement to ordinary Portland cement (OPC). The effect of the various levels of FCA (0, 25, and 50%) replacing ground granulated blast furnace slag (GGBS) in AAS mortars with 4% of Na2O dosage is studied. Further, five levels of the modulus of silica (Ms = 0.75, 1.00, 1.25, 1.5, and 1.75) are chosen to achieve targeted compressive strength at 28 days under ambient temperature curing conditions. The compressive strength decreases with the increase in level of the FCA replacement. The targeted design compressive strength is achieved with 25% FCA replacement to GGBS in the AAS mortar system with Ms = 1.25. In addition, microstructure and mineralogical studies are undertaken to ascertain the formation of different hydration products with the aid of the scanning electron microscope (SEM) and the X-ray diffractometer (XRD). Gismondine and calcium aluminate silicate hydrate (C-A-S-H) are the major hydration products in the AAS mortar mixes. Sodium aluminate silicate hydrate phases (N-A-S-H) are also observed prominently as the FCA replacement level increases in the AAS mortar mixes. The Fourier-transform infrared spectroscopy (FTIR) confirms the presence of the Si–O-(Si or Al) functional group. The addition of FCA in the AAS system is of vital significance in the reduction of the embodied carbon dioxide (ECO2eq), embodied energy (EEeq) and cost. © 2020 Elsevier Ltd
  • No Thumbnail Available
    Item
    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.
  • No Thumbnail Available
    Item
    Synergy of Hydration and Microstructural Properties of Sustainable Cement Mortar Supplemented with Industrial By-Products
    (Springer Science and Business Media Deutschland GmbH, 2024) Sumukh, E.P.; Das, B.B.; Barbhuiya, S.
    The present research assists in resolving the issues allied with the disposal of industrial solid wastes/industrial by-products (IBPs) by developing sustainable IBPs based cement mortars. The applicability of IBPs as a feasible alternative to river sand in cement mortar has been evaluated by investigating the synergy among the ingredients, resulting engineering properties and microstructural developments at early and late curing ages. The study could effectively substitute 30% volume of river sand with bottom ash and 50% in the case of slag sand mortars. The experimental outcomes disclose that the practice of IBPs as fine aggregate enhances the engineering properties of mortar and the optimum replacement level lies at 10% and 40% usage of bottom ash and slag sand, respectively. The advanced characterization studies and particle packing density illustrate the refinement of pores by void filing action and accumulation of additional hydration products through secondary hydration reactions. The consumption of portlandite followed by increased hydration products formation observed through thermogravimetric analysis, X-ray diffraction analysis and energy dispersive X-ray spectroscopy that confirmed the contribution of finer fractions of IBPs to secondary hydration reactions. This constructive development was also observed from the lowering of wavenumber corresponding to Si–O–Si/Al vibration bands in Fourier transform infrared spectroscopy spectra. The improved microstructure resulted in enhancing the compressive strength by 9.01% and 18.18% in optimized bottom ash and slag sand mortars, respectively at the curing age of 120 days. Similarly, the water absorption reduced by 1.03% and 1.24% in bottom ash and slag sand mortars, respectively. © The Author(s), under exclusive licence to the Iran University of Science and Technology 2024.
  • No Thumbnail Available
    Item
    Effect of CO2 curing on phase compositions of nano silica blended cementitious mortar partially replaced with carbonated recycled fine aggregates
    (Elsevier Ltd, 2025) Trivedi, S.S.; Ansari, F.; Das, B.B.; Barbhuiya, S.
    This manuscript examines the quantification of CO2 uptake, hydration and carbonation phases such as calcium hydroxide (Ca(OH)2, CH), calcium carbonate (CaCO3, CC), magnesite (MgCO3), hydromagnesite (MgCO3.Mg(OH)2.4H2O, Hmgs), siderite (FeCO3) and subsequent carbonation and hydration degrees (CD, HD) in cementitious mortar (CM) incorporating colloidal nano silica (CNS) and carbonated and uncarbonated recycled concrete fine aggregates (RCF) subjected to accelerated carbonation curing (carbonated RCF- CRCF, Non-carbonated RCF- NCRCF). The RCF was prepared through multi cycle jaw crushing technology followed by repeated abrasion cycles and subsequently treated using accelerated carbonation. The mass loss resulting from the breakdown of these compounds at specific temperature ranges (220–350 °C for Hmgs, 250–400 °C for FeCO3, 400–500 °C for CH, 460–900 °C for MgCO3, and 600–800 °C for CC and CO2) was calculated using a thermogravimetric (TG) analyzer. The main findings of this research work confirms the presence of vaterite, calcite, tobermorite (Ca2.25[Si3O7.5(OH)1.5].8H2O or CSH gel), and magnesite polymorphs for CM incorporating 6–9 % CRCF and 1 % CNS as validated by the increased areas of peaks from fourier transform infrared spectroscopy (FTIR) analysis at 714 cm?1, 875 cm?1, 1007 cm?1, and 1405 cm?1, respectively which is further recognized by the increased peak intensities in X-ray diffraction (XRD) analysis. The important findings from the scanning electron microscopy (SEM) analysis revealed the development of additional C-S-H and calcite phases filling the pores and densifying the matrix in CRN mixes while the Ca/Si atomic ratio significantly decreased up to 67 % for CRN-19 mix as found by the energy dispersive X-ray spectroscopy (EDAX). The fresh and hardened state properties of blended mixes highlight the increase in dry density and compressive strength that are found maximum for CRN-19 mix of 57.9 MPa at 28 days owing to the highest rate of strength contribution of 27.95 % from the mix components such as 9 % CRCF and 1 % CNS. However, the flowability is observed to get reduced for all the mixes with CRN-13 mix illustrating approximately 83 % flow values with reference to the control mix. Furthermore, the durability performance of CRCF based primary mixes and all the secondary blends are found to show lowest ingress of chloride ions and permeable porosity values, illustrating up to 73 % and 39 % fall respectively to that of control mix at 28 and 56 days cured samples. Based on the comprehensive investigation and analysis, it is recommended to use pre-carbonated RCF and CNS for developing sustainable CM and achieving CO2 sequestration. © 2025 Elsevier Ltd