Use of ash in concrete – new problems and possibilities. Use of air pollution control residue in concrete

The ash in focus is a municipal solid waste incineration (MSWI) ash from REFA A/S, Denmark. Prior to use in this project, the ash was carbonized and electrodialytically treated to remove the mobile fraction of the heavy metals as descried in [Kirkelund et al. (2010) J Appl Electrochem, 40:1049–1060] where it is named exp. 5. The chloride content is at a level where 10% cement can be replaced without concern for reinforcement corrosion in accordance to DS/EN 206-1, a simple wash of the ash in water increased this to 50%. In comparison to the limiting values for leaching of heavy metals in Restproduktbekendtgørlesen 1480 the mortar prisms with 10% ash are placed in category 3. The compressive strength (7, 14, 28 and 42 days) is at the exactly the same level for mortar prisms with 10% ash and a reference sample without ash.

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