Preparation and properties of electrically conductive aggregate made using magnetically separated fly ash

A new type of conductive aggregate was prepared by the calcination of magnetically separated fly ash (MSFA). The effects of the calcination atmosphere, calcination temperature, and iron oxide content on the electrical resistivity were studied. Experimental results show that the optimal calcination conditions are a reducing atmosphere and a temperature of 1150 °C. Iron oxides were reduced to iron by the reducing atmosphere and formed a continuous electrical path; the conductive mechanism is electron conduction. The water absorption and apparent density of the optimal conductive aggregate were 5%, and ∼2.0 g/cm3. The new series of conductive aggregates provided good electrical conductivity (volume resistivity of all conductive aggregates < 10 Ω-cm).