Sticky rice used as a building material

The secret ingredient that gives ancient Chinese mortar its legendary strength is sticky rice. An analysis of samples from the Ming Dynasty (A.D. 1368-1644) city wall in Nanjing showed why the rice is such an effective additive to lime mortars. Amylopectin, the rice compund in the mortar, provides mechanical strength and stability, and inhibits the growth of calcium carbonate crystals, resulting in a more compact and resilient binding material. Chinese scientists re-created the mortar and determined that it is ideal for restoring ancient structures. (Wikimedia Commons)

A curious anecdote from the September/October 2010 issue of Archaeology.