Non-destructive evaluation of civil structures using electromagnetic waves Pablo Juan-García, Thesis Advisor: Josep M. Torrents Department of Electronic Engineering Universitat Politècnica de Catalunya

1 st Barcelona Forum on Ph.D. Research in Electronic Engineering [2] Introduction  Increasing demand for non-destructive testing  Electromagnetic waves suitable for material characterization  need to measure by only one side  planar sensor  Material permittivity (ε m ): interaction between the medium and the electromagnetic field

1 st Barcelona Forum on Ph.D. Research in Electronic Engineering [3] Electromagnetic Methods Overview  inductive sensor for Steel Fibre Reinforced Concrete  coplanar sensor for permittivity measurements  coaxial sensor for surface measurements

1 st Barcelona Forum on Ph.D. Research in Electronic Engineering [4] Principle of measurement  Propagation velocity,

1 st Barcelona Forum on Ph.D. Research in Electronic Engineering [5] Principle of measurement  Propagation velocity,

1 st Barcelona Forum on Ph.D. Research in Electronic Engineering [6] Setting measurement  Measurement of the s 21 parameter  attenuation  loss factor  phase slope  effective permittivity  water conductivity >> dried mortar conductivity  decrease of the loss factor as the amount of water diminishes  final value: -6 dB (no significant variations during a week)

1 st Barcelona Forum on Ph.D. Research in Electronic Engineering [7] Setting measurement  Measurement of the s 21 parameter  attenuation  loss factor  phase slope  effective permittivity 1. Quick decrease of permittivity due to the leakage of excessive water 2. Setting time: cement hydration leads to a decrease in the amount of water. Main changes of temperature 3. Mortar hardening & bulk drying. Progressive stabilisation of the permittivity. 4. No significant variations in a week time (h) water ≈ 80 | mortar ≈

1 st Barcelona Forum on Ph.D. Research in Electronic Engineering [8] Steel Fibres Measurement  Measurement of the s 21 parameter  steel conductivity >> dried mortar conductivity  measurement of material homogeneity  good correlation with inductive sensor

1 st Barcelona Forum on Ph.D. Research in Electronic Engineering [9] Conclusions  need for non-destructive testing & evaluation  a planar sensor was designed and showed ability to measure civil structures when only one side is accessible  good correlation between water or fibre content and electromagnetic measurements of the propagated pulse through a mortar slice  further research:  deeper penetration  in-situ measurements

1 st Barcelona Forum on Ph.D. Research in Electronic Engineering [10] Acknowledgments  This work has been supported by the Spanish Ministerio de Ciencia e Innovación under project BIA C  The animations were prepared by Adrián Quevedo

Non-destructive evaluation of civil structures using electromagnetic waves Pablo Juan-García, Thesis Advisor: Josep M. Torrents, Department of Electronic Engineering Universitat Politècnica de Catalunya

1 st Barcelona Forum on Ph.D. Research in Electronic Engineering [13] Measurement setup  Vector Network Analyzer  HP8753C controlled via GPIB  s 21 modulus-phase measurement  wideband: 300 MHz to 3 GHz  TRL calibration suitability for planar measurements s 21 s 11

1 st Barcelona Forum on Ph.D. Research in Electronic Engineering [14] Measurement setup  Sensor design  Coplanar Waveguide (CPW)  600 x 150 x 1.6 mm FR4 substrate  1:4 exponential impedance transformer  penetration ~ 40 mm  propagation velocity

1 st Barcelona Forum on Ph.D. Research in Electronic Engineering [15] Results and discussion  permittivity: gap dependence  effective permittivity shows moisture variations in the sample  to measure real permittivity, air gap must be known

 propagation formulae  propagation constant  permittivity dependence

 multilayered CPW model

Non-destructive evaluation of civil structures using electromagnetic waves Pablo Juan-García, Thesis Advisor: Josep M. Torrents, Department of Electronic Engineering Universitat Politècnica de Catalunya