RICE CEMENT
Sticky rice mortar was invented in ancient China utilizing organic materials in inorganic mortar. A sticky rice soup was mixed with slaked lime to make the mortar and played a major role in maintaining the durability of the Great Wall of China as well as tombs, pagodas, and city walls. It has high adhesive strength, sturdiness, and waterproofing capability, and prevents weeds from growing as crude mortar made of sticky rice and burnt lime create a seal between bricks that would rival modern cement in strength. Some of the structures were strong enough to shrug off the effects of modern bulldozers and powerful earthquakes.
Recently there are considerable efforts worldwide of utilizing indigenous and waste, materials in concrete. One of such materials is the rice husk which under controlled burning, and if sufficiently ground, the ash that is produced can be used as a cement replacement material in concrete.