Field demonstration of magnetic tomography technology for determination of dowel bar position in concrete pavement.

The purpose of this study was to demonstrate and evaluate the use of magnetic tomography technology through the use of Magnetic Imaging Tools' (MIT) MIT Scan-2. The main objective was to measure the alignment of dowel bars in a few jointed plain concrete pavements in Virginia and demonstrate the applicability of the technology. The MIT Scan-2 was obtained on loan from the Concrete Pavement Technology Program. This program is managed by the Federal Highway Administration (FHWA) through a partnership with state highway agencies, industry, and academia. Dowel alignment measurements were successfully performed on both mechanically inserted dowel bars and bars on dowel baskets. Although the verification with field coring showed reasonably accurate measurements, signal interference from uncut dowel baskets, the presence of foreign metal in nearby locations, and bars deeper than 8 in can result in unreliable quantitative results. The repeatability of the measurements for bars on dowel baskets showed general agreement with the data reported from FHWA. The device was found to be user-friendly, and its field operation was simple. Thus, there is a potential benefit from using the MIT Scan-2 as a quality assurance tool for detecting dowel bar misalignment in jointed plain concrete pavement in Virginia