Guided Wave Based Corrosion Detection Of Rebar Within Concrete

The durability of reinforced concrete structures has been the major concernedissues, while the corrosion of rebar is the most prominent factor leading to thefailure of durability. Based on the guided wave theory of cylinder, this paper utilizesconventional piezoelectric wafers, which can be considered as actuators and sensors,to conduct the corrosion detection for rebar within concrete. The major contents ofthis paper are as follows:Firstly, based on the elastic wave theory on the infinite cylinder, after applyingappropriate boundary conditions, the dispersion equation of guided waves can beobtained. This equation indicates the relationship between frequency and phase andgroup velocity of guided waves. The dispersion characteristics and effects of rebardiameter are investigated based on the numerical solutions of above equations,while the effects of central excitation frequencies to amplitude of guided waves areobtained by means of finite element analysis.Secondly, experiments investigation of guided waves are carried out for plainround and deformed rebar. Voltage responses are analyzed under excitations withdifferent central frequencies, then the effects of excitation frequencies and the rib topropagation of guided waves can be concluded. Subsequently, guided waves arestudied experimentally for the rebar within concrete, their propagationcharacteristics are analyzed for this status.Finally, accelerated corrosion system is established by electrochemical methodin order to speed up the corrode of rebar within the concrete. Guided wavesmonitoring experiments on rebar within concrete are carried out through thecorrosion procedure. Status and expanding of corrosion are determined according toanalysis on the guided waves signals.