Abstract

Usage of reinforced concrete structures has very long tradition in infrastructure industry due to their low cost, high strength, robustness, sustainability along with the easy availability of raw materials. However, they also have some drawbacks such as poor tensile strength and ductility, which leads to the formation of cracks in the structures. These cracks may cause penetration of chlorides, resulting into corrosion in the reinforcement. Quality control, maintenance and planning for the restoration of these structures demands a suitable non-destructive testing and evaluation method for wide-area monitoring to detect the hidden corrosion of the rebar at an early stage. Infrared thermal wave imaging has emerged as a viable technique for non-destructive testing and evaluation of reinforced concrete structures due to its full-field, remote, fast inspection capabilities to monitor the sub-surface rebar corrosion. Among the various thermal non-destructive testing techniques the present chapter proposes a novel aperiodic thermal wave imaging technique named as Gaussian windowed frequency modulated thermal wave imaging for testing and evaluation of rebar corrosion in concrete structures.

Keywords: concrete structures, frequency modulation, image processing, matched filter, non-destructive testing, phase images, pulse compression, rebar, thermal non-destructive testing, thermal wave imaging
