Effect of seawater mixing on steel fibers in ultra-high performance fiber reinforced concrete
The effect and mechanism of seawater mixing on steel fiber in ultra-high performance fiber reinforced concrete(UHPFRC)and the driving mechanism on macro properties were studied by preparing seawater mixing UHPFRC with different cement content.According to the relevant test standards,the working performance and mechanical properties were tested.The concrete pull-out test and the cement content equivalent circuit experiment were designed.At the same time,the element distribution of the steel fiber surface was scanned by the field emission scanning electron microscope and the X-ray energy spectrometer and then the study analyzed the morphology and rust situation.Firstly,the seawater mixing will cause slight corrosion of steel fiber in UHPFRC,resulting in the increase of debonding tensile stress between steel fiber and matrix,which slightly reduce the maximum tensile stress,average bonding strength and equivalent bonding strength during steel fiber pulling.Secondly,the late compressive strength of seawater mixing UHPFRC can reach more than 90％of the reference group,which can meet its mechanical properties.Finally,seawater mixing can increase the volume resistance of UHPFRC,while the increase of cement content can reduce the volume resistance,which would also lead to the reduction of steel fiber corrosion degree.
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