From ancient practices to contemporary green building: Analyzing organic additives in Pitalkhora earthen plasters for sustainable construction

This study presents a detailed analysis of organic additives in the earthen plasters of Pitalkhora Caves (3rd–4th CE) using microscopy, polarized light microscopy, Fourier-transform infrared spectroscopy (FTIR), starch grain analysis, and gas chromatography–mass spectrometry (GC–MS). The investigation reveals a predominant presence of rice husk (91%–94%), along with minor quantities of straw and Paspalum scrobiculatum (Kodo millet) grains. Additionally, millet starch, various gums, and carbohydrates were identified, while FTIR and GC–MS analyses detected tree resin, beeswax, and safflower oil as key components. These results provide critical insights into ancient construction techniques, emphasizing the strategic use of locally available organic materials to enhance plaster performance. The findings underscore the resource-efficient approach of early builders in material selection. While traditional organic additives may hold potential for modern sustainable construction and conservation, this study does not directly evaluate their long-term durability or environmental benefits. Further research is necessary to explore their functional properties and assess their viability in contemporary applications.