Automated sensor-driven mapping of reinforcement bars

Non-destructive mapping of reinforcement in concrete elements of old buildings may be needed when changes or extensive maintenance is required. It is always needed when reliable design drawings are not available. The mapping will indicate the location of reinforcement bars and their diameters and depths of cover. The objective of the study presented here was to develop a reliable method for automated mapping of reinforcement bars. The methodology included a review of sensing devices, selection of a reliable sensing device for detecting reinforcement bars in concrete, and development of algorithmic procedure for manual and automated mapping of the reinforcement, based on the features of this tool. The sensor selected for this study was an electromagnetic covermeter. The automatic mapping mode proceeds in two major phases: (i) point determination of a bar; and (ii) straight and bent bar mapping algorithm. The algorithm was tested on a set of rebar configurations by simulation and by full-scale experiments. The results of manual mapping showed that the tolerance of the location measurement does not exceed 5 mm. The automated mapping procedure appears to be robust and reliable, and its mapping tolerance does not exceed 10 nun. Running times of automatic mapping are half as long as those of manual mapping. The efficiency of the automated mapping is expected to be higher for mapping of large surfaces. (C) 2002 Elsevier Science B.V. All rights reserved.