Investigation of sticky-rice lime mortar of the Horse Stopped Wall in Jiange

Background: The Horse Stopped Wall, built by sticky-rice lime in Jiange County Sichuan Province, is still conserved well after thousands of years of erosions by environmental conditions such as humidity variations, pollutions, air, etc. In this paper, mortar samples from the Horse Stopped Wall were characterized via X-ray diffraction, thermogravimetry, Fourier transform infrared spectroscopy, iodine-starch analysis and scanning electron microscopy in order to better understand its properties. Result: The results showed that the inorganic ingredients were mainly calcite and a small amount of lime in the mortar. There was still a small quantity of sticky-rice after such a long period of time. The reason that the lime was not transformed into calcite completely might be ascribed to it being wrapped by the sticky-rice in the mortar. Conclusions: Sticky-rice lime was traditionally used widely as a good natural architectural material in ancient China. The samples from Jiange County were characterized and the results showed that most of the lime had been transformed to calcite and the rest of which might be wrapped by sticky-rice. The reason the mortar could resist damages from its natural environment over such a long period of time is the interaction of the sticky-rice mortar and calcium hydroxide and their resulting micro structure.