Ancient Chinese structures are known for its durability. The City Wall of Nanjing (built 600 years ago), the Terracotta Army and a 2000-year-old tomb in Jiangsu province are some of the evidences of the remarkable achievements of Chinese ancient engineers.
What has been puzzling to some scientists is the composition of these structures which made them able to withstand centuries:
Scientists have long been fascinated with this unusual formula, and in recent years, different teams have conducted studies to better understand it. Researchers Jiajia Li and Bingjian Zhang spent six years collecting 378 samples of ancient mortar from 159 sites throughout China, dating from the Taosi phase (2300-1900 BC) all the way to the late Qing dynasty (1644-1911). Their numerous chemical tests found that 219 mortars from 96 locations had “organic components”—that is, small traces of starch, protein, brown sugar, blood, and oil. These mixtures have helped preserve much of China’s built landscape. As the researchers write, “the quality of mortar used in construction has played an important role in determining monument durability.”
Rice, sugar and blood were found present in the structures. But what were the reasons for using these organic materials? What chemical compositions do these substances possess that have preserved the structures?
(Image Credit: Pixabay)