Department of Civil Engineering
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Item Analyzing the effects of pickling sludge and fly ash valorized cement sand bricks(Springer Nature, 2025-07) Routroy, Srikanta; Singhal, AnupamThe 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.Item Sustainable ceramic bricks for toxic industrial waste inertization: factory scale development and characterization(Springer, 2025-07) Singhal, Anupam; Routroy, Srikanta; Bhunia, DipenduThis 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.Item Compounded fuzzy entropy-based derivation of uncertain critical factors causing corrosion in buried concrete sewer pipeline(Springer Nature, 2025-05) Rallapalli, Srinivas; Singhal, AnupamCorrosion in buried concrete sewer pipelines remains a critical challenge for infrastructure sustainability, driven by the complex interplay of environmental, material, operational, pipe-related, and physical factors with inherent uncertainty and interdependency, aspects often overlooked previously. This study introduces a novel compounded fuzzy entropy-based approach to systematically prioritize critical corrosion-inducing factors, integrating environmental (H₂S, pH, humidity, temperature, O₂), material (cement content, alkalinity, w/c ratio, porosity, permeability), pipe-related (age, length, diameter, depth, slope), operational (flow velocity, water pressure, hydraulic energy loss, sewage residence time, sewer type), and physical (soil type, corrosivity, moisture, groundwater level, external load) factors. Results identify H₂S (0.2073), pH (0.2055), humidity (0.2031), pipe age (0.2039), length (0.2019), cement content (0.2026), alkalinity (0.2015), water pressure (0.2073), flow velocity (0.2043), soil type (0.2042), and soil corrosivity (0.2025) as the most influential contributors, enabling targeted corrosion mitigation strategies and enhancing infrastructure resilience.Item Hydro-chemical profiling and contaminant source identification in agricultural canals using data driven clustering approaches(Springer Nature, 2025) Singhal, Anupam; Rallapalli, SrinivasCanal networks are vital for irrigated agriculture in semi-arid regions, yet their water quality is increasingly endangered by diffuse agro-chemical runoff and unregulated effluent discharges. Despite this growing risk, long-term, high-resolution assessments that simultaneously capture spatial patterns and seasonal dynamics remain scarce—leaving practitioners with limited evidence for targeted interventions. Addressing this gap, the study sampled ten canal sites monthly for 11 months across Charkhi Dadri District (Haryana, India) and analysed sixteen physicochemical parameters, including heavy metals and irrigation-relevant ions. A suite of multivariate techniques—R- and Q-mode hierarchical clustering, principal-component analysis (PCA), correlation matrices and one-way ANOVA—was employed to disentangle pollution drivers, while the Irrigation Water Quality Index (IWQI) translated complex chemistry into management-ready scores. Two principal components explained 72.6% of variance, with aluminium, iron and copper emerging as dominant contributors; ANOVA revealed significant seasonal shifts (p < 0.05) in these metals. Cluster analysis pinpointed contamination hotspots, and IWQI values of 67.3–85.5 classified canal water as “good” to “very good” for irrigation. By integrating granular spatiotemporal monitoring with advanced multivariate statistics, the study delivers a scalable framework for managing irrigation canals in data-limited, semi-arid landscapes.Item Bio-chelation for sustainable heavy metal remediation in municipal solid waste compost: a critical review of chelation technologies(Springer, 2025-04) Singhal, Anupam; Srinivas, RallapalliMunicipal solid waste (MSW) compost is a promising solution for sustainable urban waste management, widely used as a soil amendment and for carbon sequestration. However, heavy metals in MSW compost pose risks to ecosystems, food safety and human health. This review critically examines three decades of research (1994–2024) on heavy metal contamination in MSW compost and household hazardous waste (HHW), identifying gaps in managing these pollutants, particularly regarding hazardous waste co-disposal. It evaluates existing remediation strategies for heavy metal removal, with a focus on chemical-assisted leaching using chelating agents. Key treatment parameters—such as chelating agent concentration, pH, contact time, liquid/solid ratio, temperature and flow rate—are analysed in both batch and continuous modes. The study advocates for biodegradable chelating agents as an effective approach to enhancing MSW compost quality, with applications in landfill reclamation and agriculture. Emphasizing the need for eco-friendly heavy metal mitigation, the review underscores the importance of safe urban composting practices. The findings contribute to the circular economy and Sustainable Development Goals by promoting sustainable and safe MSW compost applications, fostering environmental protection and public health and guiding research and industry toward scalable, marketable remediation solutions.Item 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, DipenduNickel–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.