Chloride diffusion and pore structure of hybrid fiber-reinforced concrete in marine

Corrosion tests were performed on hybrid fiber-reinforced concrete (HFRC) subjected to seawater wetting–drying cycles to assess its resistance to chloride-induced deterioration. Chloride concentration and pore structure characteristics were evaluated using an automatic titration system and low-field nuclear magnetic resonance technology. The study examined the influence of three types of basalt fibers – twisted basalt fiber (BF), unstructured basalt fiber (bF), and spiral basalt fiber – on chloride concentration, chloride diffusion coefficient (K), surface chloride concentration (Cs), and the pore structure of HFRC. The results demonstrated that incorporating 1.5% BF significantly reduced the chloride concentration compared with 0.25% bF. Following a power–law relationship, the Cs increased with the number of wetting–drying cycles. In contrast, the K exhibited an inverse trend. Furthermore, increasing BF content led to a reduction in the T2 spectral area and refinement of the pore structure. Conversely, higher bF content expanded the T2 spectral area, indicating the development of larger internal pores and degradation of the pore structure. The pore system of HFRC displayed clear fractal characteristics, with overall fractal dimensions (DT) ranging from 2.883 to 2.922. A strong linear correlation was identified between DT and K.