Manufacturing Techniques of the Mortar Excavated from the Tieguai Tomb of the Northern Song Dynasty in Nanling, Southern China

Glutinous rice mortar is a traditional lime-based building material which was first used in China during the Southern Song Dynasty (1127-1279 CE) according to ancient Chinese documents. The Tieguai Tomb, dating back to the late Northern Song Dynasty (960-1127 CE) in Nanling, Southern China, was built by using mortar for its tomb chamber, making it the earliest mortar tomb found in China to date. In this study, X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), thin-section petrography, Fourier transform infrared spectroscopy (FTIR), and starch grain analyses were conducted to comprehensively investigate the manufacturing techniques of the mortar from the Tieguai tomb. The results show that the mortar is a type of organic-inorganic mixed material made of glutinous rice pulp, lime, clay, and fine sand. This finding indicates that glutinous rice mortar had already been used as a building material as early as the late Northern Song Dynasty, which is the earliest use record for this material in China. This study also provides direct scientific evidence for exploring the origin of glutinous rice mortar and is of great importance for reconstructing the history of Chinese traditional building materials and architectural techniques.