Experimental Research On The Bond-anchoring Performance Between Reinforcing Bars And Concrete During Freeze-thaw Cycle And Chloride Corrosion

Sufficient attention may be paid attention to the durability of reinforced concrete structure widespread all over the world. The concrete structures fail pre-maturity due to the lack of durability in many cases in ingress environment. Under marine conditions and de-icing environment, reinforced concrete structures, in which concrete subjected to freeze-thaw cycles and chloride ingress, resulting in corrosion of reinforcing bars, induced early deteriorations and loss their durability. This is a innegligible problem in engineering practice. The bond failure between reinforcing bars and concrete make them don't work well. It is a very important factor to influence the structural durability and bearing capacity.At present, a great deal of important results have been acquired about the experimental research on the bond-anchoring performance between corroded reinforcing bars and concrete, while there are few studies on freeze-thaw cycle and chloride corrosion. As a result, it is very meaningful for both on theory and in practice to research on the bond performance between reinforcing bars and concrete during freeze-thaw cycle and chloride corrosion, which is useful for the design of the durability of reinforced concrete structure.Combined with the Project of National Natural Fund"Numerical Experimental and Theoretical Research on the durability of modern Prestressed Concrete Structure"(50478089) and based on the former results, we choose centrally pullout test measure and make 26 pieces of specimens with strain gauge inside. The pull-out test was made after finite freeze-thaw cycle and different concentration chloride corrosion. We analyze the influence of cyclic times of freezing and thawing and the corrosion status on specimen bond strength and bond-slip, which will make contribution to study on the durability of reinforced concrete structure.Based on this purpose, the main contents of this paper are described as below:1.Study on the strength and bond-slip of specimens under freeze-thaw cycle and chloride corrosion, and systematically analyze the influence of freeze-thaw and chloride corrosion on the bond-slip of reinforcing bars and concrete.2.Through placing the strain gauge in the reinforcement bars, we analysis the varying curve of bond stress of the specimens with different length of anchorage under freeze-thaw cycle and chloride corrosion.3.Study on the position-function relationship of the specimens under freeze-thaw cycle and chloride corrosion, and the bond-slip relationship at different position along with different steel bars.The research results show that the influence of cyclic times of freezing and thawing and the corrosion degree on specimen bond strength and bond-slip is significant. With the increasing cyclic times of the freeze-thaw, the bond strength of the specimen declines rapidly. Under the same freeze-thaw cyclic times and the initial stages of corrosion status, the bond strength of the specimen improves with the increasing of the corrosion degree. The cyclic times of freezing and thawing have obvious effect on the position-function, but not for the corrosion status.