recycled cementitous materials

[mdub12]

does anyone know of any recycled materials that can be used to replace new cement in a high strength concrete mix, other than the basics like fly ash, slag, and silica fume? I have some grout taken from post tensioning ducts, would that even be a possibility, or would it pretty much be fully hydrated already, or even have adequate strength? im only trying to see what max strength i can get for a 7 day cylinder test, so durability and other factors aren't being considered, only compressive strength

 

[Ron]

To achieve high strength concrete, you are already pushing high quality materials to near their physical limits. Many recycled materials have highly variable properties, so those would provide less consistency and predictability.