Experimental Study On Corrosion Risk Of Steel Rebar In Joint Area Of UHPC Under Chlorine Salt Erosion

In recent years,ultra-high-performance concrete(UHPC)has developed rapidly in civil engineering.Compared with ordinary concrete,UHPC has ultra-high durability due to its high compactness.The porosity of UHPC is about 1/6 of that of ordinary concrete.Harmful substances such as chlorine salt should directly penetrate the protective layer of UHPC and corrode its internal reinforcement,which has a very low risk.However,the construction of large-scale or fabricated UHPC structure will inevitably have construction joints and wet joints with poor compactness.The high shrinkage of UHPC will further degrade the compactness of joints and will inevitably affect the stress and durability of UHPC structure.At present,some scholars have studied and pointed out that the joint interface is the weakest part of UHPC structure,and the research on the durability of UHPC structure joint area has not been reported.Based on this background,this paper aims to reveal the chloride corrosion risk of reinforcement in the joint area of UHPC structure through experimental research.The main work is as follows:(1)The corrosion risk of steel rebar at the interface between old and new UHPC under chloride ion corrosion was studied.A total of 12 specimens were made in this test,based on the data of natural corrosion potential,linear polarization resistance and Tafel polarization resistance,the corrosion risk of reinforcement at the interface between new and old UHPC under chloride corrosion is analyzed,the influence of the concentration of chloride ions on the interface between the old and new reinforcement and the corrosion risk of UHPC are discussed,the corrosion characteristics were demonstrated by electrochemical accelerated corrosion method.At the same time,the corrosion risk of old and new concrete interface is compared.(2)The corrosion risk of chloride along the Steel rebar-UHPC interface was studied.9steel bar concrete interface specimens were designed and manufactured to carry out chloride corrosion test.By testing the data of natural corrosion potential,linear polarization resistance and Tafel polarization resistance,the risk of chloride corrosion along the steel bar UHPC interface was analyzed,and the chloride corrosion risk of steel bar concrete interface under different types of concrete was compared.(3)The risk of chloride attack on UHPC was studied.As a reference,9 reinforced concrete specimens were designed and manufactured to carry out chloride corrosion test.By testing the data of natural corrosion potential,linear polarization resistance and Tafel polarization resistance,the corrosion risk of reinforcement in UHPC under chloride corrosion was analyzed,and the chloride corrosion risk of reinforcement in different types of concrete was compared.