9 - Quantitative estimation of rebar corrosion in reinforced concrete by thermography

Abstract

It is well known that the corrosion of reinforcing steel bars in reinforced concrete (RC) structures results in bond degradation, cracks in the concrete, and a decrease in the effective cross-section of reinforcement. As a result, the ultimate load-bearing capacity and the durability of structures could decrease. So, it is very important to estimate the corrosion of rebar quantitatively and, to this end, the development of nondestructive evaluation (NDE) techniques is in great demand. So far, conventional NDE methods have been marginally successful in identifying the degree of corrosion and the thickness of the corrosion products, in other words, in estimating the effective cross-section of rebar quantitatively. In this chapter, a very promising NDE technique that applies thermography is presented. The corrosion characteristics and behaviors of rebar in RC could be evaluated on the basis of temperature history at the concrete surface, which would vary due to heat conduction from reinforcement heated by electromagnetic induction.