Performance assessment of starchy liquid modified natural hydraulic lime mortar for carbon sequestration

Elevated atmospheric carbon dioxide concentrations are a major contributor to global warming by increasing atmospheric heat retention. They also drive climate change by altering long-term weather patterns and negatively affect ecosystems, biodiversity, and natural resources. These combined impacts accelerate environmental degradation and highlight the urgent need for effective carbon-reduction and sequestration strategies. In India, rapid population growth and urbanisation have significantly increased carbon emissions; therefore, there is an urgent need to reduce atmospheric carbon emissions. This research investigates the use of a starchy liquid to modify lime mortar to enhance carbon capture and utilisation and improve the sustainability of construction materials. The modified mortar demonstrated a 2.94% reduction in carbon emissions per kg of lime compared with the reference mortar. The carbonation rate increased to 30.8%, while the compressive strength increased by 1.59 times. These improvements are attributed to enhanced microstructural development and carbonation efficiency. X-ray diffraction and thermogravimetric analysis further validated the enhanced performance of the modified mortar by confirming increased calcite formation and enhanced carbonation. Thermogravimetric analysis showed that the CaCO3 decomposition increased from 6.15% to 7.20%, indicating a greater extent of carbonation in the modified mortar. Thus, incorporating starchy liquids shows significant potential for developing low-carbon lime mortars that support sustainable construction and improved environmental performance.