Research On The Application Of Electrical Resistance Tomography (ERT) In The Concrete Damage Detection

Non-destructive testing technology is of significant importance for ensuring the security and durability of concrete structures. As one kind of emerging industrialized nondestructive testing, Electrical Resistance Tomography (ERT) has broad prospect of application in the field of concrete damage detecting. Due to its poor conductive performance, a lot of deep research work is indispensable before ERT is applied to concrete structure damage detection. Based on the situation, in this paper, preliminary research was conducted on the electric performance of concrete, and three kinds of measuring electrodes were designed and the concrete blocks with pre-embedded hole damages and crack damages were tested respectively with the electrodes and ERT system, and objective evaluation was made on the test results with the image evaluation indexes, according to which the factors influencing the test results were analyzed.Data reference for the ERT detection system and experimental basis for the electrical parameters of structural model setting in the imaging system were provided with the research on the electrical properties of the concrete structures in this paper. The four-point resistivity method was adopted to measure the change of blocks’resistivity and the influence that moisture content had on the change of resistivity was studied. It was concluded that values of resistivity increased continuously and was relatively small at first and later on, period of constant resistivity emerged and resistivity began to change discontinuously, which means that the resistivity increased in the way of step growth. It was good for applying the ERT to damage detection when the resistivity is relatively low at the early stage, while when the resistivity was high, it was the relative stable stage that could be used to adjust the parameters about resistivity of ERT system and thus the damage detection of concrete structures with high resistance could be realized.In this paper, the detection ability of ERT system for the hole damage and crack damage was studied with the ERT detecting test for the pre-embedded hole damage and crack damage. And the testing results were analyzed with the image evaluation indexes. The main conclusions are as follows:the location and rough shapes of the hole damages could be detected effectively with the developed ERT system, but the imaging precision was expected to be improved; the soft field characteristic of electric field had adverse effects on the ERT and its influence should be reduced or eliminated in future tests; the location of the crack could be detected by ERT system, but it was necessary to make improvement for the detecting of the shape and length of the crack.