Mortars with addition of powdered graphite: Mechanical and electrical properties

Research to add more functionality to cementitious composites has been increasingly frequent to implement self-regeneration, self-monitoring and energy storage. Self-sensing Cement Composites (SSCC’s) are intelligent, multifunctional materials with an important role in the built environment scenario of the future, since it is present throughout the structure, it can promote a more comprehensive monitoring. This is one of the many possible applications for the combination of Portland cement composites and electrically conductive materials. The aim of this research is to evaluate the mechanical and electrical properties of mortars produced with Portland cement, sand and powdered graphite in the proportions of 0, 5, 10 and 15% by mass of the cement. To measure electrical impedance, an alternating current (AC) source was used to avoid the polarization effect in a circuit with electrodes in contact with the test specimens. Compressive strength and dynamic modulus of elasticity at 7 and 28 days were also evaluated to analyze the influence of graphite addition on the mechanical behavior of the mortars studied. The results show that the addition of graphite reduced the compressive strength and fluidity of the mortar in the fresh state. The electrical impedance of the mortar increased with the addition of powdered graphite, which indicated an increase in electrical conductivity.