Electromagnetic non-destructive evaluation techniques for the monitoring of water and chloride ingress into concrete: a comparative study

Abstract

One of the principal causes of deterioration in reinforced concrete structures is steel corrosion caused by the penetration of aggressive agents into the protective cover concrete layer (particularly water containing chlorides). Electromagnetic non- destructive evaluation (EM NDE) techniques are sensitive to these aggressive agents and can be used to assess concrete durability in terms of corrosion risk. The electromagnetic (EM) properties that are the focus of the study presented here are electrical resistivity and dielectric permittivity-inherent material properties that are both sensitive to degree of saturation and the salinity of the pore solution. Three EM NDE techniques suitable for the in situ investigation of concrete are used to obtain these EM properties: electrical resistivity tomography, capacimetry and ground penetrating radar. Experimental work is conducted on in a controlled laboratory environment with the aim of comparing the ability of the three EM NDE techniques to monitor the ingress of saline solutions into concrete slabs and discern between their chloride content. All three methods are found to be capable of detecting variation in water and chloride content and therefore show promise for the in situ monitoring of water and chloride ingress. However, more research is needed on the quantification of the EM properties over depth as well as on the combination of these methods in order to separate the influence of these two parameters on the EM responses

Use of electromagnetic non‐destructive techniques for monitoring water and chloride ingress into concrete

“…The higher is the concentration of the external solution, the lower is the resistivity of the saturated zone, and thus the higher is the concentration of chloride in the pore solution. Nevertheless, it is not possible at present to quantify this chloride concentration with ERT results: the convex curve shape would not correspond to classical chloride profile shape and to those obtained for this study (Du Plooy et al ). Further improvements are needed.…”

“…Using low-frequency alternating current instead of purely DC brings the advantage of avoiding electrode polarization (Hammond and Robson 1955).Secondly, concerning the EM techniques using higher frequency range (10-3000 MHz such as capacimetry or ground-penetrating radar (GPR)), the bulk permittivity of a concrete specimen is highly sensitive to the presence of water and ions, as shown by numerous studies (Robert 1998;Laurens et al 2002;Hugenschmidt and Loser 2008;Dérobert et al 2008Dérobert et al , 2009Benedetto et al 2012;Villain et al 2012;Kalogeropoulos et al 2013).Various EM techniques are capable of obtaining the EM properties of concrete over depth. An experimental study was conducted during which water and chloride ingress into unreinforced concrete was investigated (Du Plooy et al 2015). The in situ EM techniques used here are electrical resistivity tomography (ERT), capacimetry, and GPR in classical bi-static configuration (first method: reflected wave, RW) and in wide-angle reflection/refraction (WARR) configuration (second method: guided wave mode, GWM) using an innovative approach: the waveguide model (WGM).…”

Chloride Penetration into Concrete under the Coupling Effects of Internal and External Relative Humidity

“…For concrete with internal RH of above 75%, the results above highlighted that the increasing internal RH was helpful to the chloride migration in concrete, and relatively low RH required more time to migrate enough chloride ion. Analyzing the reason was that the chloride penetration was mainly by the medium of water, the chloride penetration into concrete was mainly by massive water-saturated passageways [32][33][34]. e decreasing RH resulted in a decrease in the number of water-saturated passageways in concrete and thus the chloride migration was decreased.…”

Hardware Design of Tuber Electrical Resistance Tomography System Based on the Soil Impedance Test and Analysis

“…In the Quasi-static field theory, it requires the medium of the field is homogeneous [7] . However, the absolutely homogeneous soil is difficult to achieve because soil multiphase medium is rather complexity.…”