Electrical Properties of Conductive Concrete Containing Graphite

Electrically conductive concrete has various potential non-structural functions such as self-sensing and electromagnetic shielding. Conventional concrete is a non-conductive composite, but electrical conductivity can be imparted and controlled by adding conductive additives. Since conductive concrete is a composite containing moisture and discrete conductive additives, the electrical properties of conductive concrete are very complex in nature. Understanding these properties are the fundamental requirements for developing its non-structural applications. In this research, graphite powder is used as a conductive additive for concrete with 3% by volume of cement paste. For characterizing the electrical properties, both AC (Alternating Current) impedance analysis and DC (Direct Current) measurement is performed in both wet and dry conditions, and their resistivities are calculated. The resistivity measured using DC increased with time of measurement. On the other hand, AC measurements show a consistent Bode diagram, but the resistivities decrease with the increase in AC frequency. These indicate conductive concrete with graphite is acting like a circuit containing a capacitor that stores electrical energy. Moisture plays a significant role in the electrical properties of concrete. The resistivity of concrete is lower in wet (saturated surface dry) conditions than in dry conditions. The results show that the electrical properties of conductive concrete cannot be represented by a single resistivity value and AC impedance spectroscopy is a useful method to characterize the electrical properties of concrete.