Aiming at reducing environmental burden, reused of returned concrete and use of alternative cement for a low carbon dioxide emission were studied. Waste sludge of returned concrete and those produced when scrubbing agitator trucks were died and pulverized, and the basic properties of the dehydrated sludge powder were investigated. As a binder with alkali stimulation capability, it was introduced to by-produced mineral admixture including blast furnace slag and fly ash and mortar specimens were evaluated through experiments. As a result, combined use of the dehydrated sludge powder and the by-produced mineral admixture showed comparable long-term strength and carbonation resistance with those using the ordinary portland cement, while larger dosage of superplasticizer was needed to have equal fresh properties.
