Application of Elastic-Wave Tomography to Repair Inspection in Deteriorated Concrete Structures
Katsufumi Hashimoto†, Tomoki Shiotani, Takahiro Nishida, and Toyoaki Miyagawa
Graduate School of Engineering, Kyoto University
Nishikyo-ku, Kyoto 615-8540, Japan
Currently, it is highly important to establish economical and efficient management systems for existing concrete infrastructures, in order to fulfil their service design lives and even to extend them. Severe deterioration in aging infrastructure is currently found to be a critical issue. For repairing deteriorated and damaged structures, large budgets are necessary, but budgetary restrictions are often imposed. As a result, preventive and proactive maintenance of infrastructure is desired, and inspections by non-destructive testing (NDT) methods must be applied. In terms of damage assessment and estimation of repair and retrofit recovery in concrete structures, in addition to current NDT, innovative methods must be established. For crack repair methods applied to the existing structures, inspection techniques to assess repair installations have not yet been practically developed. There are many reports that improper repair efforts have resulted in re-deterioration. Although epoxy injection and patch repair methods are widely implemented to refill internal cracks from the concrete surface, it is found in most cases that internal defects remain unknown and potentially could lead to the re-deterioration. Therefore, inspection methods to visualize internal defects in concrete must be readily implemented as a countermeasure for repair works. In the present study, the evaluation of repair effectiveness was performed in a reinforced concrete (RC) pier and a concrete wall in an existing structure. As an innovative NDT method, elastic-wave tomography is applied to evaluate three-dimensional (3D) velocity distribution before and after the repair. Penetration of the repair material and the increase in velocity due to the repair effect are visually and quantitatively identified. Additionally, a 3D tomography technique for one-side access is newly proposed, using drill-hammring to generate an elastic wave. Accordingly, the internal quality of concrete after patch repair is successfully visualized by the elastic wave velocity distribution.
-  “Damage assessment in Consideration of Repair/ Retrofit-Recovery in Concrete and Masonry Structures by Means of Innovative NDT,” Technical Committee IAM, RILEM, http://www.rilem.org/gene/main.php?base=8750&gp_id=347 [accessed August 26, 2016]
-  Y. Kobayashi, T. Shiotani, and H. Shiojiri, “Damage identification using seismic travel time tomography on the basis of evolutional wave velocity distribution model,” Structural Faults and Repair 2006 (CD-ROM), 2006.
-  Y. Kobayashi, T. Shiotani, D. G. Aggelis, and H. Shiojiri, “Three-Dimensional Seismic Tomography for Existing Concrete Structures,” Proc. of Second Int. Operational Analysis Conf., Vol.2, pp. 595-600, 2007.
-  Y. Kobayashi and T. Shiotani, “Seismic tomography with estimation of source location for concrete structure,” Structural Faults and Repair 2012, CD-ROM, 2012.
-  T. Shiotani, N. Okude, S. Momoki, and Y. Kobayashi, “Proposal of assessment method for infrastructures by AE tomography,” Proc. of 2011 National Conf. on Acoustic Emission, pp. 39-42, 2011 (in Japanese).
-  H. Asuae, T. Shiotani, T. Nishida, K. Watabe, and H. Miyata, “Applicability of AE Tomography for Accurate Damage Evaluation in Actual RC Bridge Deck,” Structural Faults & Repair Conf., No.1743, 2016.
-  H. Akaike, “Markovian representation of stochastic processes and its application to the analysis of autoregressive moving average processes,” Annals of the Institute of Statistical Mathematics, Vol.26, No.1, pp. 363-387, 1974.
-  H. Zhang, C. Thurber, and C. Rowe, “Automatic P-Wave Arrival Detection and Picking with Multiscale Wavelet Analysis for Single-Component Recordings,” Bulletin of the Seismological Society of America, Vol.93, No.5, pp. 1904-1912, 2003.
-  S. Osawa, T. Shiotani, H. Kitora, and Y. Momiyama, “Damage Visualization of Imperfectly-Grouted Sheath in PC Structures,” 31st Conf. of the European Working Group on Acoustic Emission, German Society for Non-Destructive, 2014, http://www.ewgae2014.com/portals/131/bb/fr1b3.pdf [accessed August 26, 2016]
-  K. Sassa, Y. Ashida, T. Kozawa, and M. Yamada, “Improvement in the Accuracy of Seismic Tomography by use of an Effective Ray-Tracing Algorithm,” MMIJ/IMM Joint Symposium Volume Papers, pp. 129-136, 1989.
-  Kikusui Chemical Industries Co., Ltd., Inside Pressure Hardening, http://www.kikusui-chem.co.jp/pdf/products/catalog/cat_iph_3.pdf [in Japanese, accessed August 26, 2016]
-  M. J. Sansalone and W. B. Streett, “Impact-Echo, CNondestructive Evaluation of Concrete and Masonry,” Bullbrier Press Ithaca, N.Y., pp. 29-46, 1997.
-  “Best Practices for Preparing Concrete Surfaces Prior to Repars and Overlays,” U.S. Department of the Interior Bureau of Reclamation technical Service Center, 2012.
-  Concrete Paving Technlogy, “Guideline for Partial-Depth Spall Repair,” American Concrete Pavement Association, 1998.
This article is published under a Creative Commons Attribution-NoDerivatives 4.0 Internationa License.