Alternative Ashes in Concrete

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GRØN DYST 2014 Technical University of Denmark

Alternative Ashes in Concrete
Paper
Author:A.K. Huntley (DTU Civil Engineering, Technical University of Denmark, Denmark)
R.K. Mathiasen (DTU Civil Engineering, Technical University of Denmark, Denmark)
Date: 2014-06-27     Track: Main     Session: 1

The ZeroWaste group at DTU Byg has developed methods for cleaning the ashes for pollutants (as heavy metal) and valuable materials (as phosphor), so the use of the ashes will have no environmental risk. In order to show, that cleaning the ash for heavy metals and phosphor, is indeed beneficial, phosphate has been added to a reference-mix, and tested for strength. As the phosphate affects the concrete in a negative direction, it will show how the cleaning-process is not only beneficial for the environment, but also for the compressive strength. The remaining ash can, however, not directly be used in concrete, bricks, road building or other applications as there may be problems with difficult mixing and mix designs, increase of porosity and loss of durability, strength development and final strength etc. The authors have in their project works focused on using ash in concrete and has shown that up to 20 % of the cement and up to 10% of the sand can be replaced with the sewage ash. This process reduces the water requirements, maintains the strength of the mix fairly well and still allows the mix to set and develop strength with the same speed as traditional concrete.