Carbon capture and performance enhancement of lime putty finishes with organic additives: Implications for sustainable construction and heritage conservation

• Organic additives influence on hydration and carbonation of lime putty finishes • Performance enhancement evaluation of organic lime putty finishes • Evaluated carbon capture and utilization capacity of organic lime putty finishes • Developed carbon neutral construction material for building applications . This study investigated the potential of lime putty finishes incorporated with traditional additives, i.e. kadukkai ( Terminalia chebula ) and jaggery, to enhance their carbon capture and utilization (CCU) and to produce carbon neutral material in sustainable construction and heritage conservation. Mechanical and microstructural performances of modified lime putties were analyzed with reference to compressive strength, x-ray diffraction, infrared analysis, thermogravimetric analysis, and gas adsorption techniques. These findings confirmed that organic lime putty finishes improved performance predominantly in the mechanical strength, carbon sequestration, and microstructural development. Results demonstrated that jaggery mixed putty exhibited a 39.7% higher carbonation rate with 36% higher mechanical performance, 2.5% higher CCU capacity, and better calcite crystallization than the reference, driven by enhanced porosity and accelerated CO 2 diffusion by fermentation derived alcohols. Kadukkai modified lime showed moderate carbonation and denser microstructure with enhanced formation of hydration products with high amorphous content (44.8%) in the form of amorphous calcium carbonate (ACC). Microstructural studies revealed that jaggery promotes calcite formation, while kadukkai improves ACC formations. Lime with both additives achieved balanced strength (33% high) and CCU efficiency (2.5% high), highlighting the synergistic effects of combined organics in promoting uniform carbonation with both amorphous and crystalline carbonates with controlled porosity. This investigation emphasizes the lime putty finishes pertinence as sustainable building materials, providing a practical resolution for use in heritage restoration and potentially in non-load bearing sustainable construction applications.