Rice husk

Trace elements, such as, iron, manganese, zinc, copper, lead, nickel, chromium, cobalt, arsenic, cadmium, and mercury, can be found at higher concentrations compared to bottom ash and the parent coal. Fly ash is also used as a component in the production of flowable fill , which is used as self-leveling, self-compact backfill material in lieu of compacted earth or granular fill. The strength of flowable fill mixes can range from 50 to 1,200 lbf/in² (0.3 to 8.3 mpa), depending on the design requirements of the project in question.