Working Mechanism And R&D Of Reinforcement Corrosion Monitor Based On Magnetic Field Theory

Among the durability problems of reinforced concrete structures,steel rebar corrosion is the most common durability issue.Once the steel rebar is corroded,the concrete cover is prone to cracking.In severe cases,the concrete cover will peel off.When the section of concrete and the section of steel rebar is reduced,the mechanical properties and durability of the reinforced concrete structure will decrease.Therefore,the real-time detection of the steel rebar corrosion ratio in the structure is of great significance for the control of steel rebar corrosion.And the repair measures should be taken to the damaged parts of the structure in time so that the reinforced concrete structure may continue to service.This article mainly takes the magnetic-based corrosion monitoring device(MCD)as the research object,focusing on the working principle of MCD,the influence of corrosion products on the measurement of MCD,and the detection of non-uniform corrosion using improved MCD.This research is financially supported by National Key Basic Research Program of China(973 program,Grant No.2015CB655103)and National Natural Science Foundation of China(Grant No.51578497,51378012).The research includes following parts.(1)Through numerical simulation and experimental testing,the main factors that affecting the magnetic field of MCD are analyzed.It is pointed in this research that the magnetic induction intensity is significantly related with the air gap length of MCD.And the working principle of MCD is discussed comprehensively.(2)The magnetic properties of corrosion products of steel rebar have a certain influence on the measuring results of MCD.The influence of corrosion products of steel rebar is obtained through numerical simulation and experimental investigation,and the correction coefficient induced by the presence of corrosion products is given(3)Based on the working principle of MCD,two new steel rebar corrosion monitoring instruments(NMCD1 and NMCD2)for non-uniform corrosion are developed.Numerical simulations and experimental investigation are used to verify the performance of NMCD1 in longitudinal non-uniform corrosion detection and NMCD2 in transverse non-uniform corrosion detection,which provides a feasible research method for the test of non-uniform corrosion of steel rebar.