Revealing the ancient Chinese secret of sticky rice mortar

American Chemical Society ^ | May 29, 2010 | Unknown

[decimon]

Note to journalists: Please credit the journal or the American Chemical Society as the source

WASHINGTON, May 29, 2010 — Scientists have discovered the secret behind an ancient Chinese super-strong mortar made from sticky rice, the delicious "sweet rice" that is a modern mainstay in Asian dishes. They 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. Their article appears in the American Chemical Society (ACS) monthly journal, Accounts of Chemical Research.

Bingjian Zhang, Ph.D., and colleagues note 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. 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 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 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.

"Analytical study shows that the ancient masonry mortar is a kind of special organic-inorganic composite material," the scientists explained. "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. "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," the article notes.

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Note to journalists: Please credit the journal or the American Chemical Society as the source

The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. With more than 161,000 members, ACS is the world's largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.

DOWNLOAD FULL TEXT ARTICLE: http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/ar9001944 ACS' Accounts of Chemical Research "Study of Sticky Rice-Lime Mortar Technology for the Restoration of Historical Masonry Construction"

[Tainan]

Uuuhhhh...note to "scientists"....its been well-known that people, myself included, have been putting rice powder into mortar and cement/concrete mix regularly for quite a long time.
It helps the bond and if done in the right amount makes for a 'cleaner or slicker' surface that is more water-repellent. Also makes the mortar/concrete look 'whiter.'

[Quix]

XIE XIE!

[Nailbiter]

ping

[Ellendra]

Care to share the recipe for those of us who’d like to try it? Or at least a link to a recipe?

[Tainan]

Without doing a look-up, as best as I remember is to make the rice powder about 10-20% of the mortar/concrete mix. Don't count the sand in that %.
Its more of a "this looks about right" thing for me. Just when it looks like its the consistency that will work for what you're using it for. There might be some specific recipe on the internet. Probably is.
Over here, Taiwan, bags of rice powder are sold at the 'Home Depot, Lowes' type sores ready to use.
They also have it pre-mixed for use...but it costs more.

You can make it your self by just grinding up rice to a fine powder. If you do that, use it quickly because it is very moisture absorbent and you will have a solid rock if you're not careful.

[Ellendra]

Thanks!

[SunkenCiv]

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[null and void]

Soooooo, we're going to use our corn for fuel, and China's going to use its rice for mortar.

What will people eat in the future?

[Monkey Face]

No wonder I don’t like sticky rice ~ it binds up the works!

[ErnBatavia]

Urggghhh....those of us that are early boomers picture that crap wrapped in sticky wax paper and dropped into our Halloweenie bags by the ton.

You'd see the little parcels dumped all over the area the next morning.

[afraidfortherepublic]

Bookmark for an intersting discussion...