Thread: Secret discovered behind the Great Wall of China.

Secret discovered behind the Great Wall of China's strength: sticky rice was used for mortar
By MAIL FOREIGN SERVICE
Last updated at 11:14 AM on 31st May 2010
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The delicious 'sticky' rice' that is a modern mainstay in Asian dishes was the secret behind an ancient Chinese super-strong mortar.
Researchers also concluded that the mortar - a paste used to bind and fill gaps between bricks, stone blocks and other construction materials - remains the best available material for restoring ancient buildings.
Doctor Bingjian Zhang and colleagues found that construction workers in ancient China developed sticky rice mortar about 1,500 years ago by mixing sticky rice soup with the standard mortar ingredient.

Rice Wall of China: The sweet rice favoured by the Chinese is the secret to their most famous structure's strength
That ingredient is slaked lime, limestone that has been calcined, or heated to a high temperature, and then exposed to water.
Sticky rice mortar probably was the world's first composite mortar, made with both organic and inorganic materials. The mortar was stronger and more resistant to water than pure lime mortar, and what Dr Zhang termed one of the greatest technological innovations of the time.
Builders used the material to construct important buildings like tombs, pagodas, and city walls, some of which still exist today. Some of the structures were even strong enough to shrug off the effects of modern bulldozers and powerful earthquakes.
Their research identified amylopectin, a type of polysaccharide, or complex carbohydrate, found in rice and other starchy foods, as the 'secret ingredient' that appears to be responsible for the mortar's legendary strength.
Dr Zhang said: 'Analytical study shows that 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.'
To determine whether sticky rice can aid in building repair, the scientists prepared lime mortars with varying amounts of sticky rice and tested their performance compared to traditional lime mortar.
Dr Zhang said: 'The test results of the modelling 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.'
The research was published in the journal of the American Chemical Society.



Read more: Sweet rice the secret to Great Wall of China's strength and longevity | Mail Online

Should this be in the cookery thread?

I have watched brick makers in Thailand, who were restoring and old temple, put rice husks in the mix

Phew. I thought they had found my stash of porno mags