Great Wall of China Secret: It’s Edible! Sort Of… Please Don’t Eat It.
Slaked lime was a key ingredient in the construction of the Great Wall of China. But Zhejiang University scientists have discovered a surprising additive: Congee, a sticky rice porridge. The sticky rice dish contains amylopectin. When that combines with calcium carbonate, it creates a “compact microstructure” so strong it can withstand natural events like storms and earthquakes.
While its strength is considered average when compared to other mortars, it is water resistant, shrinks less, and the chemicals in the mortar actually make it stronger over time. This was the first true composite mortar known to history. While the use of sticky rice for Great Wall construction was controversial at the time, because it took rice away from the workers and used it in mortar instead. Despite the hungry, resentful workers, the sticky was incredibly successful. The mortar is still so strong in places that weeds cannot grow through it.
