Influence of free electron charge and free extra framework anions in calcium aluminate@ rGO (CA@ rGO) cement composites with enhanced dielectric and electrochemical properties

•The CA@ rGO cement composites were successfully prepared by a conventional thermal reduction method without any toxic chemicals.•The as-prepared CA@ rGO cement composites exhibited high performance in both dielectric constant and electrochemical capacitive properties.•The synergistic effect of free electron transfer and diffuse between CA cement interface and rGO nano sheets, enhancing the high dielectric and electrochemical properties of CA@ rGO cement composites.