BITS Faculty Publications
Permanent URI for this communityhttp://localhost:4000/handle/123456789/1867
Browse
6 results
Search Results
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.Item Comprehensive assessment of leaching characteristics in electric arc furnace slag-based alkali-activated mortar(Springer, 2025-03) Lahoti, MukundThis study investigates the leaching resistance and environmental performance of electric arc furnace slag (EAFS) as a precursor in alkali-activated materials (AAMs), contributing to sustainable construction practices and reducing reliance on conventional cement. The research employs detailed leaching analysis to evaluate the chemical stability, environmental impact, and long-term performance of EAFS-based AAMs (EFAM). Key findings reveal stable pH values in leachate samples, indicative of precursor properties and effective alkali activation, alongside increasing electrical conductivity over time due to the formation of durable ionic bonds. The release of heavy metals, such as Zn, Cu, and Cr, decreases significantly after 60 days, highlighting effective stabilization mechanisms. Distinct leaching patterns of oxyanions like arsenic and chromium, coupled with minimal leachability of elements such as molybdenum and barium, emphasize the material’s environmental safety. Additionally, calcium in the system reduces the mobility of certain elements, ensuring compliance with environmental standards. All leached metals remain below detection limits across samples, confirming the suitability of EFAM for construction applications without adverse ecological effects. This study underscores the relevance of thorough leaching analysis in validating the safety and sustainability of novel construction materials, paving the way for their broader adoption in eco-friendly construction.Item Tailoring Properties of Electric Arc Furnace Slag Based Geopolymer Through Fly Ash Incorporation(Springer, 2023-02) Lahoti, MukundGeopolymers are novel binders and are sustainable alternatives for conventional Portland cement. Geopolymers have emerged as a phenomenon of exceptional interest for the construction industry due to their excellent mechanical properties and sustainability in the past few years. A significant factor in producing geopolymers is the selection of the precursors. In this study, electric arc furnace slag (EAFS) obtained as waste from the steel industry is used as the precursor, and the influence of fly ash (FA) on the properties of the developed geopolymer is investigated. Scanning electron microscopy (SEM), X-Ray diffraction (XRD), and X-ray fluorescence (XRF) are used for material characterization and for analysing the microstructural development.Item Effect of sodium hydroxide concentration on EAFS based alkali activated binder(Elsevier, 2023-04) Lahoti, MukundThe emission of greenhouse gases primarily CO2 during the production of cement is a substantial global threat. Along with this the disposal of industrial waste is also a key concern due to leachate. In order to lower the emissions and make better use of industrial waste, a novel technology termed alkali-activated binder (AAB) can be a potential alternative to ordinary portland cement. In the past few years, AAB’s have been a phenomenon of remarkable interest to the construction sector because of their exceptional mechanical qualities and sustainability. The selection of the source material is a critical factor to develop AAB’s. This research attempts to utilize the electric arc furnace slag (EAFS) generated from the production of steel through EAF route as the primary precursor. Four different variations of sodium hydroxide (SH) molarity (8, 10, 12, and 14) were used to investigate its effect on the fresh and mechanical properties of EAFS-based AAB. The alkali to binder ratio of 0.40, curing temperature 80 °C, and 85% humidity were used for preparing the AAB. Scanning electron microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), X-ray fluorescence (XRF), and X-Ray diffraction (XRD), are used for material characterization and for analyzing microstructural development.Item Recycling electric arc furnace slag through tailoring of ambient-cured alkali-activated mortar mix using hybrid AHP-GRA and TOPSIS(Elsevier, 2024-05) Lahoti, MukundUtilizing Electric arc furnace slag (EAFS) as a precursor for alkali-activated mortar production reduces waste and supports alternative cement binders. Since the mix design includes multiple factors, the Taguchi DoE was employed by varying the modifier (fly ash) to precursor (EAFS) ratio (0–75% by mass), activator to precursor ratio (A/P) (0.52–0.66), sodium hydroxide (SH) concentration (8–14 M), and sodium silicate to sodium hydroxide ratio (SS/SH) (1.5–3.0). Analytic hierarchy process (AHP) weighted Grey relational analysis (GRA), and technique for order preference by similarity to ideal solution (TOPSIS), were utilized to achieve a high performing mix. Performance characteristics encompass flowability (flow%), final setting time (FST), compressive strength (f'cu), and flexural strength (f'cr). The optimized mix possessed 75% flowability, 575 min FST, 38 MPa f'cu, 16 MPa f'cr, and 3.75% water absorption. Precursor-to-modifier ratio dominates the mix design. The three mixes—optimized (M17), top-ranked (M8), and least-ranked (M1) were micro-structurally examined using powdered X-ray diffraction, X-ray fluorescence, scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy.Item Mitigating environmental impact by development of ambient-cured EAF slag and fly ash blended geopolymer via mix design optimization(Springer Nature, 2024) Lahoti, MukundThis article discusses the utilization of industrial by-products, namely, electric arc furnace slag (EAFS) and fly ash to produce cementless geopolymer binder. Taguchi-grey optimization is used for experimental design and for investigating the effects of mix design parameters. Fly ash, in the levels of 0–75% (by mass), partly replaced EAFS in the binary-blended composite system. Experiments were performed on the microstructural development, mechanical properties, and durability of ambient-cured EAFS-fly ash geopolymer paste (EFGP). The optimal mix with 75–25% composition of EAFS and fly ash produced ~ 39 MPa compressive strength accrediting to the co-existence of C-A-S–H and N-A-S–H gels. The initial and final setting times were 127 min and 581 min, respectively, owing to adequate alkali and amorphous contents in the matrix, and the flowability was 108% due to sufficient activator content and the spherical shape of fly ash particles. SEM, XRD, and FTIR results corroborated the mechanical test results.