Improving the Durability and Interfacial Reinforcement of Basalt Fibers by Coating with Graphene Oxide to Improve the Stability of Concrete in Frozen Soil with Saline

Abstract Concrete in frozen saline soil regions are highly vulnerable to coupled deterioration caused by chloride attack and freeze-thaw cycles, which imposes increasingly requirements on its durability. Although basalt fiber (BF) can effectively reinforce cementitious materials, its smooth and chemically inert surface weakens interfacial bonding with the cement matrix, thereby limiting its reinforcing efficiency. Fortunately, graphene oxide (GO) has been proven to strengthen the BF-cement matrix interfacial transition zone (BF-ITZ) through its unique nanostructure and abundant oxygen-containing functional groups. However, the effects of different wrapping strategies and the underlying enhancement mechanisms remain unclear. This study proposed a three-step GO wrapping strategy to enhance the BF-ITZ and compared its performance with that of the physical impregnation method. Macroscopic and microscopic experiments coupled with molecular dynamics simulation were combined to systematically investigate the mechanical properties and microstructural evolution of BF-reinforced concrete under water and 3.5% NaCl freeze-thaw environments. NaCl transport models in GO/C−S−H gel nanopores were further explained at different temperatures to reveal the migration behavior of NaCl solution and the atomic-scale blocking effect of GO. The results showed that GO-wrapped BF concrete exhibited 33.16% and 64.3% higher compressive strengths and 19.1% and 22.9% higher flexural strengths than concrete with unmodified BF under water and chloride freeze-thaw environments, respectively, after 200 freeze-thaw cycles. Molecular dynamics simulation revealed that increasing temperature from 255 K to 300 K promoted water and ion migration, whereas GO increased nanopore tortuosity and enhanced the adsorption of Na+ ions and water molecules through its oxygen-containing functional groups, thereby weakening NaCl solution transport and restricting Cl− diffusion. The experimental and simulation results indicate that BF crack bridging and GO-induced microstructural regulation synergistically delay damage evolution under coupled chloride attack and freeze-thaw cycling, highlighting GO-wrapped BF as an effective strategy for improving concrete durability in saline soil regions.