Sticky rice was used in the mortar of many Ming dynasty Great Wall sections.
Builders mixed sticky-rice soup or paste with slaked lime to make a rice-lime mortar for joining bricks and stones. The unusual organic ingredient supplied starch, especially amylopectin, which helped produce a dense and durable bonding material.
The technique was part of a broader Chinese building tradition rather than a recipe unique to the Great Wall. Sticky-rice mortar was also used in city walls, tombs, pagodas, and other major structures. Scientific studies of historic mortars have identified rice-related organic material and found that it could improve cohesion, strength, and resistance to water penetration.
The wording “Ming dynasty sections” matters: the Great Wall contains structures from many periods, and not every section used the same materials. Earlier walls commonly relied on rammed earth, while Ming builders made extensive use of bricks, stone, lime, and specialized mortar. Sticky rice was an additive in the binder—not a replacement for the wall’s bricks or stones, and certainly not the wall’s main bulk.