Research On A New Type Of Fiber Bragg Grating Based Corrosion Sensor For Rebar Corrosion Monitoring

Reinforced concrete structure is one of the most widely used structures in civil engineering. Reinforced concrete structures exhibit perfect durability under normal working conditions. But the rebar corrosion process will accelerate if they are exposed to aggressive environments, such as chloride ion. Rebar corrosion will not only bring huge direct and indirect economic losses, and cause waste of raw materials, resources and energy, but also will seriously reduce the durability of reinforced concrete structures, and even cause structural damage. Therefore, rebar corrosion monitoring is significantly important.Part of research work on design and application of fiber Bragg grating (FBG) corrosion sensor is done in this paper, the main research work includes the following aspects:(1) Summarize the existed rebar corrosion detection/monitoring methods, and analyze the main shortages of these methods.(2) Calculation formula of the theoretical corrosion rate is derived from Faraday’s law and the experimental results is compared with the theoretical corrosion rate. This experiment demonstrates that the theoretical corrosion rate can be employed to assess the process of rebar corrosion.(3) Based on the principle of FBG strain sensor and the fact that the rebar will expand greatly after corrosion, a new type of FBG corrosion sensor is proposed in this paper. The structure and working principle are introduced.(4) Performance of the FBG corrosion sensor is checked by experiment. Experimental results show that the new type of corrosion sensor has advantage of relatively large measurement range of corrosion rate.(5) Experimental results show that the increase in temperature of the rebar is not large, which demonstrates that an accelerated electrochemical corrosion test in research of FBG corrosion sensor is feasible.(6)The feasibility of using FBG corrosion sensor for monitoring of concrete hydration heat to guide the construction process is discussed.(7) In combination with the elastic mechanics analysis method, ANS YS finite element numerical analysis method and the existing experimental results, the warning points of FBG corrosion sensor are discussed.