Effects of aramid fibers in corroded reinforced concrete beams

Chloride-induced corrosion of steel reinforcement is a major durability deterioration in reinforced concrete (RC) structures. Since concrete is a relatively brittle material, the presence of cracks in RC provides a path for ingress of oxygen, water, and chloride ion to reach the steel reinforcement in the RC structures. To improve cracking behavior to prolong the durability of RC structures, fiber reinforced concrete (FRC) is a practical solution to limit the critical cracking in RC structures by the addition of discrete fibers mixed into the concrete. However, the most used common fiber, steel fiber (SF), is susceptible to corrosion and still possesses question in its performance in a chloride environment. Aramid fiber (AF), which is high strength and non-corroded synthetic fiber, is used in this study. In this study, hybrid beams, consisting of Aramid Fiber Reinforced Concrete (AFRC) in the bottom half and conventional concrete in the top half, were designed to investigate the performance of AF in cracked beams subjected to chloride environment in the simulated wet-dry cycles. This study aims to investigate the effects of AF in corroded cracked RC beams. A total of 4 types of AF with different lengths (30 mm, 40 mm and 50 mm) and surface conditions (plain and twisted) were investigated and compared to 35 mm hook-end SF. The structural performance evaluation of corroded cracked hybrid beams was carried out by a four-point bending test. Also, corrosion levels in the main rebars were investigated.The test results showed that the use of AF can enhance load capacity and improve cracking behavior of the tested beams. After a total of 329 days of chloride exposure, the performance of corroded cracked beams was tested through four-point bending test and corrosion test. The tests revealed that the structural performances of corroded hybrid AF (HAF) beams were found to be similar or better than the uncorroded beams. These enhanced structural performances are beneficial for specific purposes such as structures in marine environment where rebar corrosion is the main concern for serviceability, durability and load carrying capacity. Moreover, the discussion and conclusion of the suitable type of fiber for severe chloride environment were drawn in this study.