Conductive aggregate prepared using graphite and clay and its use in conductive mortar

A new type of conductive aggregate was proposed and prepared for the first time by calcination of ceramic matrix and dispersed graphite powder. The prepared conductive aggregate was used in mortar containing carbon fiber, and the specimens’ electrical resistivity and piezoresistivity were studied. Results show that optimal graphite powder content in conductive aggregate is 10 wt.%. The use of conductive aggregate in mortar significantly improved its electrical conductivity. The resistivity of conductive aggregate mortar (CAM) was lower than that of ordinary aggregate mortar (OAM) by one to two orders of magnitude, at the same content of carbon fiber. Volume contents of conductive aggregate and carbon fiber had an important effect on the resistivity and piezoresistivity of mortar. A conductive aggregate volume content of 30% of mortar and a carbon fiber volume content of 0.6% of cement paste portion are recommended for attaining good electrical conductivity (the volume resistivity of mortar is less than 100 Ω cm) and piezoresistivity.