Influence of NaCl Solution External Erosion on Corrosion Resistance of RPC Reinforced with Straw Fiber

Straw fiber, as a kind of waste if not properly treated, will pollute the environment. It can be used in cement-based materials as a plant fiber material. Agricultural solid-waste straw fiber has good tensile properties and is expected to be used as a fiber-reinforced material for reactive powder concrete (RPC) and to improve the corrosion resistance of RPC. In this paper, the ultrasonic velocity through specimens, the electrical resistance, the AC impedance spectroscopy and tafel curve were analyzed. The corrosion resistance of the steel bar under the chloride salt freeze–thaw cycles and dry–wet alternations was systematically studied. The result shows that adding a certain content of straw fiber can improve its corrosion resistance. Under the action of two chloride salt environments, the lowest mass loss rate was 0.82% for the sample with 3% straw fiber content and the mass growth rate of the specimens with 4% straw fiber is the highest aqt 0.9%. In terms of ultrasonic velocity, the lowest loss rate was 5.68% for specimens with fiber content of 2%. The specimens were subjected to 0 dry–wet alternations and freeze–thaw cycles; the highest electrical resistance is 19.96 kΩ when the fiber content is 1% and the lowest electrical resistance is 11.105 kΩ when the fiber content is 2%. Under the dry–wet alternations, the content of straw fiber and its corrosion resistance are: 1% > 4% > 0% > 3% > 2%. Under freeze–thaw cycles, the content of straw fiber and its corrosion resistance were as follows: 1% > 0% > 4% > 3% > 2%.