Corrosion of Ultra-high Performance Concrete(UHPC)Modified Steel Fiber in Chlorideion Environment
The corrosion resistance of steel fibers,the primary reinforcing material in ultra-high performance concrete(UHPC),was enhanced by subjecting them to heat treatment at different temperatures(150℃,300℃,450 ℃,and 600 ℃).This treatment,aimed at advancing the corrosion resistance of steel fibers and promoting the use of UHPC in corrosive environments,involves incorporating the modified steel fibers into the raw materials for UHPC production.Subsequently,UHPC and steel fibers(including a control group)were immersed in a 3.5％chloride ion solution for 100 days.Corrosion resistance analysis of the steel fibers is conducted using electrochemical methods and microscopic morphology analysis.The results indicate that,with increasing heat treatment temperature,the corrosion resistance of the modified steel fibers gradually improves.After undergoing treatment at 600 ℃,the oxide scale on the steel fibers exhibits the highest corrosion resistance and the most compact surface morphology.However,the degree of corrosion resistance declines significantly at this temperature compared to all other heat treatment temperatures.Following immersion,no apparent standard form of corrosion product FeOOH is observed on the surface rust layer of the original steel fibers.At heat treatment temperatures of 150℃,300 ℃,and 450℃,the rust layer displays a dual-phase structure,with a decrease in α-FeOOH and an increase in γ-FeOOH as the treatment temperature rises.At a heat treatment temperature of 600℃,the rust layer on the steel fibers generates not only α-FeOOH and γ-FeOOH but also β-FeOOH,which promotes corrosion.
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