Design And Characterization Of Anticorrosive Fiber Reinforced Ultra-High Performance Marine Concrete

The strategy of becoming a maritime power is a comprehensive macro-strategy that leads the overall development of China’s maritime affairs.It is also a necessary measure to expand China’s living and development space,strengthen international cooperation,and move towards the world.Maritime engineering construction serves as the foundation of the maritime power strategy,with reinforced concrete being the most commonly used material in such construction.However,traditional reinforced concrete exhibits insufficient durability,significant corrosion of reinforcing steel,and a short service life under harsh marine environments,which severely impacts the long-term stability and maintenance of marine structures.Enhancing the durability of maritime concrete can be achieved by improving its impermeability.Based on the theory of particle packing,the development of ultra-high-performance concrete(UHPC)with excellent impermeability has provided an ideal material for maritime engineering construction.However,UHPC is inherently brittle and prone to cracking,often requiring the addition of steel fibers to overcome its brittleness in practical engineering applications.However,the use of steel fibers in the preparation of marine concrete has always been controversial,limiting the large-scale application of UHPC in marine environments.The use of corrosion-resistant fibers such as polymer fibers as a substitute for steel fiber reinforcement in UHPC can fundamentally eliminate the risk of steel fiber corrosion and provide a material basis for the stable maintenance of marine structures.Existing research has been conducted on the use of glass fibers,basalt fibers,carbon fibers,and polymer fibers in the production of concrete,but the research specifically focused on corrosion-resistant fiber-modified UHPC is not sufficient.Moreover,existing studies mainly establish the correlation between the types and dosages of corrosion-resistant fibers and the compressive strength and toughness of UHPC,lacking a systematic evaluation of the durability of corrosion-resistant fiber-reinforced UHPC.Based on this,this study utilizes polyethylene fibers as corrosion-resistant fibers to design and fabricate corrosion-resistant fiber-reinforced UHPC for marine engineering.It systematically evaluates its macroscopic performance evolution and long-term performance under harsh environmental conditions,providing a material foundation for marine construction.The main research and conclusions of this paper are as follows:(1)Based on the theory of particle packing,a dense and compact ultra-highperformance concrete(UHPC)matrix is designed using the Modified Andreasen Andersen(MAA)model.On this basis,the influence of adding corrosion-resistant fibers(polyethylene fibers,PEF)on the performance of UHPC is revealed,and the optimal PEF dosage is determined to prepare corrosion-resistant fiber-reinforced UHPC.(2)The tensile tests and Digital Image Correlation(DIC)system are used to evaluate the ductility and toughness of corrosion-resistant fiber-reinforced UHPC.By analyzing the stress-strain behavior,the constitutive relationship of the mechanical properties of corrosion-resistant fiber-reinforced UHPC is obtained.The results show that the tensile strength of corrosion-resistant fiber-reinforced UHPC slightly decreases compared to traditional steel fiber-reinforced UHPC,but the strain-hardening rate significantly improves,leading to a more obvious ductile failure mode and better toughness enhancement.Digital image analysis reveals that under tensile stress,PEF-reinforced UHPC exhibits multiple cracking,which is the main reason for achieving high ductility and toughness.(3)The impact resistance of corrosion-resistant fiber-reinforced UHPC is studied using the Split Hopkinson Pressure Bar(SHPB)apparatus.The results indicate that under different strain rates,the dynamic compressive strength of PEF-reinforced UHPC is lower than that of the steel fiber system,while steel fiber-reinforced UHPC is more sensitive to strain rate changes.PEF deteriorates the energy absorption capacity of UHPC but reduces the critical damage.Considering the static and dynamic mechanical properties of the system,dynamic constitutive models are established for both the steel fiber(SF)and PEFreinforced UHPC.(4)The long-term performance of corrosion-resistant fiber-reinforced UHPC is systematically evaluated through rapid chloride migration tests(RCM method),underwater abrasion resistance tests,and real-sea exposure tests.The results show that corrosion-resistant fiber-reinforced UHPC exhibits higher impermeability.Additionally,the abrasion resistance of corrosion-resistant fiber-reinforced UHPC is significantly improved,attributed to the flexible PEF providing a buffering effect,reducing the impact of steel balls on the matrix.A one-year real-sea exposure test shows no significant changes in the appearance of corrosion-resistant fiber-reinforced UHPC,while steel fiberreinforced UHPC exhibits noticeable steel fiber corrosion behavior at an early stage.This study designs and fabricates corrosion-resistant fiber-reinforced UHPC,providing a systematic analysis of the static,dynamic mechanical properties,and longterm performance of UHPC.It offers material foundations and theoretical support for the long-term safety and stable maintenance of marine structures.