The latest research from Shenzhen University and Jinan University has unveiled advancements in the application of carbon fiber composites within civil engineering, with a focus on both the recycling of carbon fibers and their integration into reinforced concrete structures. These findings, published in Engineering, provide fresh perspectives on the sustainable and functional utilization of carbon fibers, potentially reshaping the future of the construction industry.

The study, titled “Evolution Mechanism of Carbon Fiber Anode Properties for Functionalized Applications: Impressed Current Cathodic Protection and Structural Strengthening,” delves into the electrochemical properties of carbon fibers and their potential applications in impressed current cathodic protection (ICCP) and structural strengthening (SS). The research highlights the development of an integrated technology known as ICCP-SS, which combines cathodic protection with structural reinforcement to extend the lifespan of reinforced concrete (RC) structures.

Carbon fibers are renowned for their high strength, light weight, and corrosion resistance, making them ideal for various applications, including civil engineering. However, their use as electrode materials in civil engineering environments has been relatively underexplored. This study investigates the anode electrochemical behavior of carbon fibers in strongly alkaline and high-chloride environments, which are typical in coastal and marine settings.

The researchers discovered that carbon fibers exhibit improved anode performance in such environments due to the formation of oxidized functional groups on their surfaces. These groups weaken the van der Waals interactions between the graphene layers of the carbon fiber, allowing solvated anions to insert between the layers and causing expansion of the interlayer gap. This process, while leading to the degradation of the carbon fiber structure, also enhances its electrochemical activity.

Building on this understanding, the study introduces the ICCP-SS system, which utilizes carbon fiber-based multifunctional anodes (CFMAs) to protect steel reinforcements from corrosion while simultaneously strengthening the concrete structure. The CFMAs are designed to act as both anodes and structural reinforcements, effectively combining electrochemical protection with mechanical enhancement.

The ICCP-SS system is particularly advantageous for coastal RC structures, where high chloride ion concentrations in seawater pose a significant corrosion risk. By integrating CFMAs into these structures, the researchers demonstrated that the system could significantly extend the service life of RC structures, potentially by at least 40 years under the most unfavorable conditions.

Moreover, the study addresses the challenge of recycling carbon fibers, which are typically difficult to separate from their matrix materials at the end of their service life. Traditional recycling methods, such as thermal and chemical processes, often result in significant degradation of the fibers’ properties. In contrast, the electrochemical recycling method developed by the researchers offers a non-destructive alternative. By optimizing polarization conditions, they achieved a debonding rate of 99% and maintained 95% of the original tensile strength of the recycled fibers.

The recycled carbon fibers were then used to create reinforced composites, demonstrating mechanical strengths comparable to those of virgin fibers. This innovative recycling method not only reduces environmental pollution but also promotes the sustainable use of carbon fibers in various industries.

The research presented in Engineering offers a comprehensive exploration of the electrochemical properties of carbon fibers and their potential applications in civil engineering. The development of the ICCP-SS system and the electrochemical recycling method represents a significant step towards sustainable and functional use of carbon fibers, promising to enhance the durability and safety of RC structures while reducing maintenance costs and environmental impact.

The paper “Evolution Mechanism of Carbon Fiber Anode Properties for Functionalized Applications: Impressed Current Cathodic Protection and Structural Strengthening,” is authored by Ji-Hua Zhu, Qujian Li, Chun Pei, Hongtao Yu, and Feng Xing. Full text of the open access paper: https://doi.org/10.1016/j.eng.2025.03.005. For more information about Engineering, visit the website at https://www.sciencedirect.com/journal/engineering.