The two well known methods for measuring the covers of the reinforcing bars in concrete are the electromagnetic induction method and the electromagnetic wave radar method. The former has the problem of decreased measurement accuracy when the bars are deep or when the bars are heavily corroded. The latter utilizes the B-mode image of the received wave signals. Therefore, the accuracy is not high, although it can be used to measure the cover of bars at a wide range of depths. This paper proposes a new method to measure the cover using the signal propagation model of the electromagnetic wave (EMW), which one of the authors developed previously. The method utilizes A-mode signals to accurately measure the propagation time of the EMW under the complicated environment of receiving many unwanted reflected waves from the other reinforcing bars and then applies Snell’s law to the propagation times to measure the cover. A field test demonstrated that highly accurate measurement is achievable using the proposed method, with the average and maximum error rates as low as 1.9% and 3.5%, respectively.

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In petrochemical plants, many pipelines exist under various operating conditions, and some of them are too aged. Recently the aging of piping has caused serious accidents in many plants. Therefore, it is important to manage the lifetime of a piping system. Many of these accidents have been generated because of the failure to notice localized metal decrease in pipe-thickness caused by corrosion and/or erosion. Such oversight should be found in both the inspection planning stage and the measuring stage. The authors have developed a continuous thickness measurement system utilizing ultrasonic waves which scans metal loss in piping, including elbows, and reports the piping thickness distribution. In this report, the system performance and application are briefly shown.

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