A Study on the Measurement of Steel Corrosion in Mortar by TEM Method

J. Ocean Eng. Technol. 2006;20(2):59-65.

Lee Sang-Ho;Han Jeong-Seb;

Division of Architecture, Civil & Environment Engineering, Hanzhong University;Division of Civil & Ocean Engineering, Dong-A University;

TEM법에 의한 모르타르 중의 철근 부식 측정에 관한 연구

이상호;한정섭;

한중대학교 건축.토목환경공학부;동아대학교 토목.해양공학부;

Keywords: Spatting, Transient electro magnetic(TEM) method, Steel corrosion, Secondary electro Motive force(2nd EMF), Coincident loop configuration, Nondestructive technique

핵심용어: 박리, 과도전자탐사법, 철근 부식, 2차 기전력, 동일루프배열, 비파괴 기술

Abstract

Steel, as a reinforcing mechanism in concrete, provides the tensile strength that is lacking in concrete, alone, and the high alkaline environment (pH 12.5) in concrete offers satisfactory protection against most corrosion of the steel. However, the corrosion of reinforcing steel in concrete can occur by chloride attack or carbonation, and it can cause a loss of integrity a section and concrete failure through cracking and spalling. In this study, a transient electro magnetic method (TEM) of a nondestructive technique is adapted to study the measuring method of steel corrosion in mortar. The sensor was made of an enameled wire, with a diameter of 0.25mm and anacril. He sensor configuration used was a coincident loop type. The secondary electro motive force (2nd EMF) was measured with SIROTEMIII, which equipped the accelerator. The accelerator allowsthe transmitter to turn off approximately $10sim15$ times faster than normal. The high-resolution time series, used for very shallow or a high resistivity investigation was selected. After steels were corroded by the salt spray, during 4, 8, 15 and 25 days, they were embedded in mortar. The content results acquired in this study are as follows. The variation of the secondary electro motive force (2nd EMF) was shown by the change of steel surface with different corrosion time steel. It was confirmed that measurement of steel corrosion in mortar by a transient electro-magnetic method (TEM) can be possible.