Advanced composite materials are being used for seismic retrofit of reinfor
ced concrete (RC) columns designed and constructed by old specifications. T
he writers are currently developing an electromagnetic (EM) imaging technol
ogy for assessing damage of the columns covered by such jackets, specifical
ly debonding at the adhesive bonding layer between the jacket and the colum
n. This technology takes advantage of the difference in electrical properti
es (including conductivity and dielectric constant) between the adhesive ep
oxy (under a good bonding condition) and air tin case of debonding). In thi
s paper, an inversion method is presented that can efficiently and accurate
ly reconstruct electrical property images (profiles) from continuous sinuso
idal EM waves of different frequencies launched toward and reflected from t
he layered medium, such as the composite-adhesive-concrete medium. This inv
ersion method consists of a forward model and an iterative optimization pro
cess. By comparing the wave signals sent to and reflected from the medium,
the reflection coefficient of each layer of the medium can be measured and
the electrical property profile (EM image) can be inverted. Using the inver
ted electrical property, the forward model computes the reflection coeffici
ent. The jacobian matrix method is applied to modify the inverted profile i
nteractively to minimize the error between the measured and calculated refl
ection coefficient. A constrained optimization technique is introduced in o
rder to achieve maximum stability of the inverted profile against noise. At
the present stage, simulation study is carried out in which the electric p
roperty image for the bonding layer is Satisfactorily reconstructed and deb
onding successfully detected using the proposed inversion method.