alternative materials: AshCrete

Image of micron-sized earth elements in AshCrete

Through my research in sustainability in architecture, I've become intrigued by the studies of Pliny Fisk. Fisk has made a significant contribution to the progression of sustainability in architecture and is pioneering new techniques and materials on this path. One material I have run across that he has coined as AshCrete, is an alternative material to Portland Cement. AshCrete is made of 97 percent recycled materials.


The discovery came about when Fisk mixed a couple spoonfuls of water into a teacup filled with fly ash from a coal fired power plant. The result was a material with the compressive strength twice that of Portland Cement. AshCrete is a mixture of fly ash, bottom ash from aluminum smelters, and a dash of citric acid, borate, and a chemical from the chlorine family (not mentioned)- which he is seeking a substitute for. One concern mentioned about the production of this material is the fine silicon inherent in the composite material, which poses no threat embedded in the concrete, but may cause respiratory disease if exposed to overtime in a factory. These concerns are ones that Fisk is attempting to resolve.
Replacing Portland Cement with AshCrete would reduce the overall carbon dioxide emissions, because the manufacture of concrete generates about 9 percent of CO2 emissions globally, and secondly it would reduce the waste stream of fly ash left over by coal-fired power plants .