Thermal and Mechanical Performance of Natural Additive Organic Mortar Sheets for Cold Rooms

Post-harvest losses of agricultural produce caused by inadequate storage infrastructure remain a significant challenge in developing countries. Conventional cold storage insulation materials such as polyurethane foam and polystyrene-based panels present environmental, durability, and disposal concerns. This study reports the development and experimental evaluation of eco-friendly insulation sheets fabricated using lime mortar incorporated with natural organic additives. A pilot cold storage room with a volume of 1200 ft³ (≈ 34 m³) was considered for performance evaluation. The lime mortar composites were prepared using jaggery, aloe vera gel, fenugreek powder, neem oil, kikkar gum, plaster of Paris, and glass fibre reinforcement. Mechanical properties were evaluated through compressive and transverse strength tests following relevant Indian Standards, while thermal conductivity was measured using the Guarded Heat Flow Meter method (ASTM C518). The developed sheets exhibited compressive strength values ranging from 20 to 30 N/mm² and a transverse bending strength of 289.7 N/mm². Thermal conductivity values were observed between 0.06 and 0.09 W/m·K. Field application demonstrated an indoor temperature reduction of 8–12°C, with relative humidity maintained within 15–65%. The results confirm that organic additive-based lime mortar sheets offer a sustainable, low-cost alternative for cold room insulation in agro-based industries.