Corrosion performance of reinforced activated powder concrete in simulated seawater

The durability failure of marine concrete is primarily induced by the erosive effect of seawater, exacerbated by freeze-thaw and wet-dry cycles. Reactive powder concrete (RPC) renowned for its high strength and durability, undergoes further enhancement when reinforced with fibers. In structures the fiber RPC is commonly reinforced with rebars. This study aims to investigate the seawater erosion resistance of rapid-strength RPC with fibers and rebar, five groups of reinforced RPC specimens with steel fibers, basalt fibers, and hybrid fibers were fabricated, and the erosion solutions were prepared with reference to the seawater composition of a specific region. Then freeze-thaw cycle and wet-dry cycle tests were carried out. The mass loss rate and electrochemical parameters according to Tafel curve were conducted. The result reveals that: the mass loss rate, resistivity, corrosion current density and corrosion rate of each group of reinforcing RPC gradually increase with the increase of cycles of freeze-thaw or wet-dry. With the influence of rebar and fiber, the mass losses of the specimen increase at low cycle times. Under the same times of freeze-thaw cycles or wet-dry cycles, the resistivity, corrosion current density and corrosion rate of the reinforcing RPC specimens with hybrid fibers of steel and basalt are all smaller. Compared with the Tafel curve after 300 freeze-thaw cycles, the voltage value corresponding to the extreme point after 40 cycles of dry-wet cycles is smaller, indicating that the corrosion of steel bars is more severe under the action of dry-wet cycles. The RPC mixed with 0.5% basalt fiber +1.5% steel fiber shows the best performance to resist salt freezing and wet-dry cycle performance.