Department of Civil Engineering

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Author: search.filters.author.Routroy, SrikantaSubject: search.filters.subject.Civil engineering

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    Analyzing the effects of pickling sludge and fly ash valorized cement sand bricks
    (Springer Nature, 2025-07) Routroy, Srikanta; Singhal, Anupam
    The disposal of Stainless-Steel Pickling Sludge (SSPS) in landfills remains an important issue. Utilizing SSPS as construction material mitigates the negative environmental effects associated with its disposal, providing a sustainable solution. This study investigates co-utilization of SSPS and fly ash as partial substitution of river sand on cement sand bricks properties. Nine cement sand bricks compositions, including control mix, were prepared with varying composition of SSPS, fly ash and river sand. Four compositions were developed with SSPS varied from 2.5 to 10% with fixed fly ash content of 50%. Four additional compositions with varying fly ash content from 40 to 47.5% and varying SSPS 2.5–10% content as partial substitution of river sand were prepared. The developed bricks demonstrated that gradual increment of SSPS (2.5–10%) and reduction of fly ash (47.5–40%) proved incremental to the compressive strength up to 28 MPa. In addition, the morphological analysis using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and X-ray Fluorescence (XRF) were conducted for the compositions. The microstructure analysis showed that with inclusion of fly ash, Mix 2 (M2) compositions revealed a dense microstructure validating the sorptivity results as compared to Mix 1 (M1) compositions. Finally, the cost estimation of the waste valorized bricks as compared to the control bricks was observed to be significantly low. The experiment outcomes concluded adoption of SSPS-fly ash waste valorized bricks as a greener alternative to disposal.
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    Sustainable ceramic bricks for toxic industrial waste inertization: factory scale development and characterization
    (Springer, 2025-07) Singhal, Anupam; Routroy, Srikanta; Bhunia, Dipendu
    This work reports factory-scale development of cleaner ceramic bricks with the incorporation of hazardous nickel chromium electroplating sludge (NCS) obtained during chrome-plated steel production. The NCS is particularly rich in chromium and nickel, the two metals used for chrome plating. Earlier attempts to incorporate NCS in ceramic bricks faced substantial strength reduction due to heavy metals’ presence. We engineered a high-volume incorporation of pulverised coal fuel ash (PFA) along with NCS and tested 20 compositions with varying proportion of the three ingredients. The optimum composition was obtained with 37.5% PFA, 12.5% NCS, and remaining clay soil. The optimum composition bricks witnessed substantially enhanced density and compressive strength, reduced water absorption and efflorescence. XRD analysis indicated formation of spinel structure and mullite leading to strength enhancement. SEM analysis indicated increased pore filling in brick matrix with PFA cenospheres. XRF analysis revealed appreciable presence of fluxing oxides in NCS which facilitated the sintering process. Additionally, higher amount of reactive silica and alumina in PFA led to formation of stronger ceramic bonds. Leaching tests by Toxicity Characteristic Leaching Procedure indicated negligible release of heavy metals, indicating successful immobilization of heavy metals. The developed methodology provides the relevant stakeholders an eco-friendly, economical, readily deployable scheme for eliminating the mounting NCS accumulation.
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    Synergic valorization of nickel-chrome plating sludge via alkali activation of steel slag and fly ash: performance analysis
    (Springer, 2024-09) Lahoti, Mukund; Singhal, Anupam; Routroy, Srikanta; Bhunia, Dipendu
    Nickel–chromium plating sludge (NCPS) is a hazardous waste due to high concentration (~ 25%–30%) of chromium and nickel. Electric arc furnace slag (EAFS) is a by-product of secondary steel manufacturing through the electric arc furnace route. In this work, we valorized NCPS in an innovative ambiently cured alkali-activated NCPS-Fly ash-EAFS mortar (ANFEM). NCPS substituted the binder from 0 to 25% (by weight) in the step size of 5%. The binder composition had EAFS/fly-ash = 1.0, activator/binder = 0.45, silicate/hydroxide = 2.5. Incorporation of NCPS in ANFEM resulted in several benefits such as successful NCPS immobilization, improving the flash setting and flowability issues of alkali-activated EAFS and minimal degradation in mechanical properties. Microstructural investigation by XRD, FTIR, SEM offered insights on the underlying mechanisms of NCPS valorization and corroborated the observed results of compressive strength, water absorption, bulk density, acid resistance, and surface porosity test. At 10 wt% substitution of NCPS, ANFEM produced optimum results, such as compressive strength of 40 MPa; Wabs enhancement by 4.2%; bulk density reduction by 1.1%; and the least acid-induced deterioration. Extensive leaching tests determined leachate’s heavy metals concentration to be well-within the permissible limits. Factory scale deployment of developed methodology produced paver blocks well-satisfying Indian Standard Code 15,658: 2006.