Upgraded MSWI Bottom Ash as Aggregate in Concrete

The objective of this research was to examine the technical feasibility of upgraded bottom ash from municipal solid waste incinerators as fine and coarse aggregate in concrete. The effect of partial replacement of natural sand and gravel by such bottom ash on all relevant properties of concrete (technological, structural as well as durability and reuse as recycled aggregate) has been determined. Based on these findings a guideline has been formulated for the use of upgraded incinerator bottom ash in ready-mixed as well as precast concrete. Although the upgraded bottom ash is of better quality then the original bottom ash, some properties still need special attention (i.e. must meet additional requirements): particle density, metallic aluminium content, loss on ignition, chloride, sulphate and alkali content and, finally, constituents which alter the setting and hardening of the cement. Upgraded incinerator bottom ash can replace up to 20 % V/V sand and/or gravel in reinforced concrete and up to 50 % V/V in plain concrete (non-structural concrete). Application in prestressed concrete is not recommended because of the possibly higher risk of stress corrosion in the prestressed steel.