Sticky Rice is Secret Ingredient in Great Wall of China's Strength

great wall of china photo

photo: Kevin Poh via flickr

I normally don't cover traditional building methods, but this one is a bit too cool. Scientists from Zhejiang University in China have discovered one what may be the secret ingredient in the Great Wall's strength and longevity: Sticky Rice. Well, sticky rice soup mixed with slaked lime and limestone to be exact.Times of India reports the scientists discovered that a combination of those ingredients was mixed together to make a paste which was used to fill in gaps between the construction blocks.

Study leader Bingjian Zhang:

Analytical study shows the ancient masonry mortar is a kind of special organic-inorganic composite material. The inorganic component is calcium carbonate, and the organic component is amylopectin, which comes from the sticky rice soup added to the mortar.

Moreover, we found that amylopectin in the mortar acted as an inhibitor: the growth of the calcium carbonate crystal was controlled, and a compact microstructure was produced, which should be the cause of the good performance of this kind of organic-organic mortar.

The test results of the modeling mortars shows that sticky rice-lime mortar has more stable physical properties, has greater mechanical strength, and is more compatible, which make it a suitable restoration mortar for ancient masonry."

sticky rice photo

photo: Robin via flickr
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