Browsing by Author "M, N."

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Carbon sequestration and life cycle assessment of an industrial waste-derived carbon sink binder under saline water utilization
(Taylor and Francis Ltd., 2025) M, N.; Palanisamy, T.
The development of low-carbon construction materials is essential to meeting global climate targets. This study presents a carbon-negative binder synthesized primarily from iron-rich industrial byproducts (mill scale), supplemented with fly ash, metakaolin, and limestone. Oxalic acid enhances iron dissolution and promotes stable carbonate formation during CO2 curing. Strength development occurs through direct CO2 mineralization, with carbonation curing conducted at 0, 1.5, and 3 bar using both normal and saline water. Specimens cured at 3 bar with saline water achieved compressive strengths exceeding 60 MPa and carbon sequestration rates up to 1.03% per day. Carbonation depth followed a square-root time relationship, with enhanced propagation under high-pressure saline conditions. Microstructural analyses (XRD, TGA–DTG, FTIR, FESEM) confirmed the formation of siderite, lepidocrocite, nesquehonite, and calcite within a dense matrix. Life Cycle Assessment indicated approximately 85% lower fossil-based global warming potential and over 80% reductions in water consumption compared to Ordinary Portland Cement, demonstrating a potable-water-free, resource-efficient binder suitable for circular and climate-resilient infrastructure. © 2025 Informa UK Limited, trading as Taylor & Francis Group.
Formulation of a carbon sink binder through multi-objective optimization using response surface methodology
(Elsevier B.V., 2025) M, N.; T, P.
This study presents the development and multi-objective optimization of a cement-free, carbon-sequestering binder system formulated entirely without Ordinary Portland Cement. The binder integrates iron-rich industrial waste, fly ash, metakaolin, and limestone, activated through oxalic acid to promote iron carbonate formation during CO? curing. Response Surface Methodology was employed to model and optimize the combined effects of oxalic acid dosage, CO? curing pressure, CO? and air curing durations, water-to-binder ratio, and specimen geometry on compressive strength. The statistical model demonstrated high predictive reliability R² = 0.9847; predicted R² = 0.949 with a desirability score of 1.000. An optimized formulation comprising 2 % oxalic acid, 3 bar CO? curing pressure, 14 days of CO? curing, 5 days of air curing, and a water-to-binder ratio of 0.17 achieved an experimental compressive strength of 62.8 MPa with only 3.41 % absolute error from the predicted value. This strength exceeds typical neat cement paste ranges 25–35 MPa, highlighting the system's potential as a viable cement paste substitute. Microstructural analyses XRD, FTIR, FESEM confirmed the formation of siderite, calcite, goethite, and dense low-porosity matrices, while TGA-DTG validated CO? uptake via carbonate formation. Over 75 % of the binder consists of upcycled industrial waste, supporting circular economy goals and significantly reducing embodied carbon. The generalized regression model enables predictive strength estimation across curing regimes and mix designs, offering a reproducible, scalable approach for developing high-performance, low-carbon construction materials. © 2025 The Author(s)
Oxalic acid optimization for iron-based solid waste conversion into a carbon-sequestering composite building material
(Elsevier B.V., 2025) M, N.; Palanisamy, T.
The cement industry significantly contributes to global CO2 emissions, accounting for approximately 164 million metric tonnes annually, while total emissions from all sources reach 37 billion metric tonnes. Concurrently, the iron and steel sector generates substantial waste, producing about 500 kg of waste per tonne of steel. Addressing these environmental challenges is crucial for sustainable development. This study presents a sustainable alternative to traditional cement by developing a novel binder material composed primarily of waste iron. The alternative binder not only avoids CO2 emissions but also absorbs CO2 during carbonation curing, effectively contributing to carbon sequestration. Key parameters, including particle size, oxalic acid dosage, and water-to-binder ratio, were individually tested and analyzed for their impact on compressive strength, leading to the finalization of a 75?m particle size and a 0.2 water-to-binder ratio, which yielded compressive strengths of up to 45 MPa. The wet mix method for oxalic acid incorporation demonstrated superior performance compared to the dry mix approach. Comprehensive analyses, including XRD, FTIR, TGA/DTG, and FESEM, confirmed the enhanced reactivity and performance of the material with finer particles and optimized oxalic acid dosage. By utilizing 80% of waste materials, this alternative binder addresses both waste management and carbon capture, aligning with global sustainability objectives and advancing the development of eco-friendly building materials. © 2024 Elsevier B.V.