Integrating tradition and sustainability: Organic additives in 2ndcentury BC Bhaja Caves for carbon-neutral construction solutions

Abstract

This study examines the composition of ancient earthen plasters from the Bhaja Caves using advanced analytical techniques, including microscopy, Fourier-transform infrared spectroscopy (FTIR), gas chromatography-mass spectrometry (GC/MS), and starch grain analysis. The findings reveal a predominance of organic additives, particularly rice husk, comprising 87 % to 88 % of the plaster matrix, along with paspalum grains, bast fibers, millet, mung bean starch, beeswax, and natural resins. These components function as sustainable binding agents, enhancing the durability and flexibility of the plaster. The high silica content in rice husk, coupled with the binding properties of starches and the inclusion of natural oils and resins, reflects a holistic, nature-based construction methodology practiced for centuries. This study is highly relevant to heritage conservation, sustainable construction, and eco-friendly material development. By demonstrating the effectiveness of biodegradable and renewable materials in ancient plaster formulations, the findings offer valuable insights for modern conservation efforts of historical structures and the development of carbon-negative building materials. The research has direct applications in the fields of archaeology, architectural conservation, and green building technologies, providing a blueprint for integrating agricultural by-products into contemporary construction. By reducing reliance on synthetic materials, this approach contributes to sustainability goals, resource efficiency, and circular economy principles.