Unravelling the composition and provenance of mud plasters in the Aurangabad Caves: a multifaceted analytical approach

This research investigates India's mud plaster heritage, focusing on the composition and provenance of materials used in historical structures, with a case study of the Aurangabad Caves (6th–8th AD). These caves, located in the Sahayadri range, feature mural works on basaltic rock supported by mud plaster that has deteriorated over time due to coarser grain soils and loss of binding capacity. Using a multifaceted analytical approach—including FTIR, XRD, ICP-MS, SEM–EDX, and particle size analysis—this study examines the geological adaptation of these mud plasters. The findings reveal a consistent mineralogical composition across various caves, including plagioclase, quartz, calcite, and kaolinite, with calcite acting as a durable binder. FTIR spectra confirm the presence of hydroxyl groups, aliphatic hydrocarbons, calcite, quartz, clay, and organic binders. Soil samples from Harsul Lake near the caves match the plasters' mineralogical and chemical profiles, indicating a probable source of raw materials. These insights are crucial for developing compatible plasters for restoration and have significant implications for preserving historical structures globally, underscoring the importance of understanding traditional building materials.