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.Fine aggregates

Search Results

Now showing 1 - 6 of 6
  • No Thumbnail Available
    Item
    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.
  • No Thumbnail Available
    Item
    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.
  • No Thumbnail Available
    Item
    Performance characteristics of self-compacting concrete containing lateritic fine aggregate as a partial replacement to natural river sand
    (Institute of Physics, 2024) Kiran Bhat, K.; C, C.; Das, B.B.
    This study identifies the use of processed lateritic fine aggregate (LFA) as a sustainable material for the replacement of natural fine aggregate (NFA) in self-compacting concrete (SCC). Cubes were cast with LFA replacements from 10% to 80% with an interval of 10% for checking the compressive strength development at 28 and 90 days. The findings demonstrate that the replacement of 30% NFA with LFA leads to the optimum performance, resulting in compressive strengths of 45.5 MPa and 53 MPa after 28 and 90 days of curing. Similar trends are also noted with the specimens cast for splitting tensile and flexural strengths as per IS 516: 2021. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Thermogravimetric analysis (TGA), and Fourier Transform Infrared Spectroscopy (FTIR) were performed to understand the surface morphology, material characterization, and composition differences between the control mix (C30F) and optimized lateritic SCC (C30F30L). SEM and EDX analysis demonstrated the contribution of the introduced fly ash particles to the strengthening of concrete. TGA with DTA has shown the more complicated denser structure of the C30F mix, and FTIR has confirmed the presence and formation of the C-S-H gel. Si-O-Si asymmetric stretching band has extra peaks, and with FTIR, O-C-O asymmetrical bending and stretching wave band have a lower intensity than the C30F mix due to the partial replacement of LFA. In addition, it is also observed from the durability studies that C30F30L showed an increase in pore volume and capillary pore network compared to C30F mix. © 2024 The Author(s). Published by IOP Publishing Ltd.
  • No Thumbnail Available
    Item
    Carbon capture efficiency of ultrafine cementitious substituents and fine aggregate alternatives subjected to accelerated CO2 curing
    (Elsevier Ltd, 2025) Trivedi, S.S.; Ansari, F.; Karthik Kumar Goud, P.; Joy, S.; Das, B.B.; Barbhuiya, S.
    This manuscript examines the quantification of CO2 uptake, calcium hydroxide (Ca(OH)2, CH) and calcium carbonate (CaCO3, CC) formed for processed recycled concrete fines (RCF), supplementary cementitious materials (SCMs) and various sustainable fine aggregate alternatives subjected to accelerated carbonation process. A thermogravimetric (TG) analyser was used to enumerate the mass loss consequential from these compounds' breakdown at particular temperature range (400–500 °C for CH, 600–800 °C for CC, and CO2). The increased areas of peaks from fourier transform infrared spectroscopy (FTIR) analysis confirmed the presence of calcite and vaterite polymorphs for carbonated RCF and SCMs at 875 cm?1 and 714 cm?1 respectively whereas the formation of calcium silicate hydrate (Ca2.25[Si3O7.5(OH)1.5].8H2O or CSH gel) is confirmed by the increased stretching vibrations of Si-O bond at 970 and 1030 cm?1. The X-ray diffraction (XRD) found the presence of useful compounds such as aragonite, calcium silicate hydroxide (Ca4Si5O13.5(OH)2) and portlandite that further confirmed the carbonation of RCF, SCMs and various fine aggregate alternatives. The formation of these compounds in carbonated specimens resulted in a significant fall in Ca/Si atomic ratio to a maximum of 98 % that further signifies the denseness in microstructure owing to precipitation of CaCO3 and CSH gel deposition. The filled cracks and pores represented by scanning electron microscopy (SEM) images in carbonated specimens demonstrates the suitability of adopted carbonation regimes. The physical performance of RCF, SCMs and various fine aggregate specimens post accelerated carbonation highlights the increase in bulk density, specific gravity and reduced water absorption levels and volume changes that is an area of grave concern for incorporating recycled materials in construction sector. In addition, the CO2 uptake of various carbonated specimens is found using TG analysis demonstrates the highest uptake for RCF at 32.4 % surpassing various other utilised SCMs and fine aggregate alternatives used in the research work. It is to be noted that metakaolin and ultrafine fly ash shows minimal CO2 uptake owing to the manufacturing process. The findings of this study recommend the use of processed RCF and various other SCMs and fine aggregate alternatives for potential carbon dioxide sequestration through accelerated carbonation technology. © 2024 Elsevier Ltd
  • No Thumbnail Available
    Item
    Enhancing sustainability with ternary blended cement and fine aggregate in self-compacting lateritic concrete with supplementary materials
    (Elsevier Ltd, 2025) Kiran Bhat, K.; C, R.; Das, B.B.
    This study explores an innovative approach to sustainable self-compacting concrete (SCC) by partially replacing natural fine aggregate (NFA) with lateritic fine aggregate (LFA) and manufactured sand (M-sand). Additionally, fly ash and ultrafine ground granulated blast furnace slag (UGGBS) were introduced as supplementary cementitious materials to enhance performance. Fresh properties of the SCC mixes met as per Indian standards, demonstrating satisfactory flowability, passing ability, and stability. Among the mixes, the combination of 30 % fly ash (30 F), 30 % LFA (30 L) and 50 % M-sand (50 M) replaced in the conventional SCC mix, designated as C30F30L50M, exhibited optimal workability and segregation resistance. Mechanical tests revealed improvements in long-term strength, with the optimized mix containing 5 % UGGBS showing superior flexural strength at 90 days. Durability assessments indicated increased water absorption in mixes containing LFA and M-sand, while the control mix displayed better resistance to chloride penetration. Microstructural analyses (SEM, XRD, TGA/DTG, and FTIR) confirmed enhanced hydration and phase development influenced by the blend of fine aggregates and supplementary materials. The findings highlight the potential of utilizing LFA and M-sand in SCC to achieve sustainable concrete with improved performance characteristics. © 2025 The Authors
  • 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