Incinerator bottom ash
Incinerator bottom ash (IBA) is a form of ash produced in incineration facilities. This material is discharged from the moving grate of municipal solid waste incinerators. Following combustion the ash typically has a small amount of ferrous metals contained within it. This ash can be processed to standardize the material and remove contaminants in order for it to be used as an aggregate. Following processing the material can be termed IBA aggregate or processed IBA. The aggregate uses for the material include:
- Bulk fill
- Asphalt via re-melting at 1200 C to form slag, but energy intensive.
- Cement bound materials
- Lightweight blocks
- Pavement concrete
Alternatively if there are no local markets for the IBA the material is typically disposed of in a landfill.
If IBA is used as the aggregate in foam concrete in non-ventilated areas, hydrogen gas deposits may build up during the lifespan of the material and explode when brought into contact with sources of ignition, such as during cutting with grinding equipment. Suspicion of this has resulted in its use being banned by at least two firms in the US and brought about further investigation by the Health and Safety Executive.
- "Exploding concrete banned". ContractorJournal. 11 November 2009. Retrieved 11 November 2009.