Sticky rice mortar

Hydraulic mortar was not available in ancient China, possibly due to a lack of volcanic ash.

[3] Sticky rice mortar had high adhesive strength, sturdiness, waterproofing capability, and prevented weeds from growing as crude mortar made of sticky rice and burnt lime created a seal between bricks that would rival modern cement in strength.

During the Ming dynasty (1368–1644 AD), brick-making techniques improved significantly in terms of quantity and quality of production.

[4] Since then, Great Wall sections were widely built with bricks, with lime mortar and sticky rice used to reinforce the bricks strongly enough to resist earthquakes and modern bulldozers while keeping the building intact.

Modern chemists, through their research, identified amylopectin, a type of polysaccharide, or complex carbohydrate, found in rice and other starchy foods to appear to be responsible for the sticky rice mortar's strength and durability.