Introduction In the marine environment, reinforced concrete components are extremely vulnerable to corrosion by harmful ions in seawater, resulting in a serious damage. The impressed current cathodic protection method is one of the effective methods for corrosion protection of reinforced concrete structures. Conventional anode materials such as stainless-steel mesh, magnesium mesh and zinc alloy materials can effectively prevent the corrosion of passivated steel bars, but metal anode materials have some problems such as difficult laying operations, high-cost, susceptibility to corrosion and poor long-term durability. Thus, non-metallic composites, especially conductive cementitious materials can be used as promising anode materials. Conductive cementitious materials are simple to prepare, low-cost, adaptable to different concrete surfaces, and have a possibility of being reused. In this paper, a high-strength, low-permeability cement-based anode material was proposed due to its surface protection and conductive anode functions. Two kinds of cement-based anode materials were prepared in the laboratory, which were high-strength conductive mortar materials mixed with carbon fibers (CF) and carbon nanofibers (CNF) as well as conductive mortar materials embedded with carbon fiber net cloth, respectively. The mechanical properties, resistivity, and impermeability of the two anode materials were tested, and the evolution of the properties under the ICCP accelerated electric field was investigated.Methods The cementitious material of the mortar matrix was composed of P.O 42.5 cement and silica fume, the particle sizes for two types of quartz sand were 0.11-0.21 mm and 0.21-0.38 mm, a high-performance polycarboxylate superplasticizer was used, and a water-binder ratio is 0.26. In the carbon fiber conductive mortar, carbon fibers (in volume fractions of 0%, 1.0%, 1.5%, 2.0%) and carbon nanofibers (in volume fractions of 0%, 0.6%, 0.9%, 1.2%) were mixed. The single layer carbon fiber net cloth with a mesh size of 5 mm and was placed vertically on the surface of the specimen. The anode materials were cured at 90 ℃ for 72 h.The anode materials were subjected to the flexural and compressive strength tests (GB/T 17671—2021). Electrical resistivity tests (two-electrode method) were conducted on anode materials cured for different durations. Also, gas permeability tests and one-sided water absorption tests (EN 13057) were carried out to assess the permeability resistance of the anode materials. The performance degradation of the anode materials under the influence of electrical current was tested through cathodic protection acceleration experiments. The designed current density for external electrical current was 20 mA/m2. Acceleration tests were conducted by increasing the current density to 100 times (i.e., 2 000 mA/m2) and 150 times (i.e., 3 000 mA/m2). The corrosion status of the rebar was determined by a model ASTM C876 standard test method to assess the effectiveness of the anode materials in the cathodic protection test. The microstructure of the anode materials after ICCP acceleration test at an acceleration voltage of 30.0 kV was characterized by a model VEGA3 TESCAN scanning electron microscope.Results and discussion For carbon fiber conductive mortar, the mixing of CF with CNF improves the mechanical properties and conductive properties of the carbon fiber conductive mortar matrix. The compressive strength and flexural strength of mortar with 1.0% CF + 0.6% CNF are increased by 28% and 66%, respectively. There is a binding effect between CF and matrix, which can significantly improve the bending strength and increase the toughness of the material, CNF has a nucleation effect and a filling effect, which refines the pore structure inside the material, and the bridging effect of CNF improves the mechanical properties of the material. The resistivity of the mortar fiber-doped with 2.0% CF + 1.2% CNF is 160 Ω·cm, which is as low as nearly one ten-thousandth of that of the mortar fiber-undoped, this is a result of the formation of a conductive network inside the mortar specimen formed via the interconnection of CF and CNF.For carbon fiber conductive mortar with embedded carbon fiber net cloth, the introduction of carbon fiber net cloth improves the mechanical properties of the material. This is due to the fixed distribution of a layer of carbon fiber net cloth in the matrix, which constrains the cracking process of the material. Carbon fiber mesh cloth is woven from carbon fibers. The current conduction path between the fibers is more complete. The introduction of carbon fiber net cloth, CF, and CNF improves the conductivity of the composite mortar materials.Carbon fiber conductive mortar and carbon fiber conductive mortar with embedded carbon fiber net cloth both have superior impermeability properties. Intrinsic gas permeability Kv and capillary water absorption rate S are as low as one-tenth of ordinary concrete, indicating that the prepared anode material has a superior physical protection function.The cathodic protection accelerated test proves the effectiveness of the anode material. The mechanical properties and electrical conductivity of the anode material after energized slightly deteriorates. The compressive and flexural strengths are decreased by only 14.5% and 12.1%, and the resistivity is increased by 18.1%. The anode impermeability of carbon fiber conductive mortar decreases. The impermeability of a conductive mortar embedded with carbon fiber mesh cloth and carbon fiber as an anode material does not change significantly because carbon fiber mesh cloth has a main conductive effect to protect the integrity of the substrate.Conclusions The cement-based anode materials both had the superior mechanical properties, i.e., the compressive and flexural strength of 103.0 MPa and 14.6 MPa, respectively, the resistivity of 160 Ω·cm, the gas permeability and capillary water absorption rate of only 1/10 of the ordinary concrete. The concrete structure had a positive physical protection effect. After the ICCP acceleration, the mechanical properties and electrical conductivity of the two materials only produced a slight deterioration phenomenon, in which the anode material with carbon fiber net cloth performed more consistently. It could be suitable for cathodic protection of concrete with applied current. The cement-based anode materials can be also used for electrochemical chloride extraction of concrete components under high chloride salt environment conditions instead of the conventional anode materials.