Sticky rice morter helds great wall together

Telegraph:

Workers built the Ming dynasty sections of the Great Wall about 600 years ago by mixing together a paste of sticky rice flour and slaked lime, the standard ingredient in mortar, said Dr Zhang Bingjian.

The sticky rice mortar bound the bricks together so tightly that in many places weeds still cannot grow. However, there was widespread resentment against the Wall in the south of China because the Ming emperors requisitioned the southern rice harvest both to feed the workers on the Wall and to make the mortar.

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"The organic component is amylopectin, which comes from the porridge of sticky rice that was added to the mortar," he said.

"The inorganic component is calcium carbonate, and the organic component is amylopectin, which comes from the sticky rice soup added to the mortar. This amylopectin helped create a compact microstructure, [giving the Great Wall] more stable physical properties and greater mechanical strength," he reported in the journal of the American Chemical Society.

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We should give that a try on the Mexican border wall. We should also consider the design of the Great Wall which provided an excellent view that would prevent people approaching the wall undetected.