Recovered & reborn
Rice husk ash
Burnt rice hulls, nearly pure reactive silica. Every rice-growing district produces mountains of husk; controlled burning turns the residue into a cement enhancer.
How it behaves
A strong pozzolan: small doses densify and strengthen concrete and lime mortars while cutting cement demand. Raw husk itself insulates lightweight roofs and panels.
Where it belongs
Every rice belt: eastern and southern India, Southeast Asia
In a modern project
Blended cements and lime mortars in rice country; husk-filled insulation boards; ash-stabilised earth blocks.