This paper measures the geometry and the amount of corrosion of a steel bar using different methods: mass loss, calipers, drainage measurements, 3D scanning, and X-ray micro-computed tomography (XCT).
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Method Article
Applicability Analysis of Assessment Methods for Morphological Parameters of Corroded Steel Bars
In This Article
Summary
Abstract
The irregular and uneven residual sections along the length of a corroded steel bar substantially change its mechanical properties and significantly dominate the safety and performance of an existing concrete structure. As a result, it is important to measure the geometry and amount of corrosion of a steel bar in a structure properly to assess the residual bearing capacity and service life of the structure. This paper introduces and compares five different methods for measuring the geometry and amount of corrosion of a steel bar. A single 500 mm long and 14 mm diameter steel bar is the specimen that is subjected to accelerated corrosion in this protocol. Its morphology and the amount of corrosion were carefully measured before and after using mass loss measurements, a Vernier caliper, drainage measurements, 3D scanning, and X-ray micro-computed tomography (XCT). The applicability and suitability of these different methods were then evaluated. The results show that the Vernier caliper is the best choice for measuring the morphology of a non-corroded bar, while 3D scanning is the most suitable for quantifying the morphology of a corroded bar.
Introduction
Corrosion of a steel bar is one of the principal reasons for deterioration of a concrete structure and is caused by concrete carbonation and/or chloride intrusion. In concrete carbonation, corrosion tends to be generalized; while in chloride intrusion, it becomes more localized1,2. No matter what the causes are, corrosion cracks the concrete cover from radial expansion of corrosion products, deteriorates the bond between a steel bar and its surrounding concrete, penetrates the bar surfaces, and decreases the bar cross-sectional area considerably3,4.
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Protocol
1. Testing the Specimen and the Manufacturing Process
- Acquire a 500 mm long, 14 mm diameter plain steel bar (grade Q235) for the manufacturing of the test specimens.
- Polish the surface of the bar using a fine sandpaper to remove the mill scales on the surface.
- Cut the bar at 30 mm and 470 mm from its left end, as shown in Figure 1, using a cutting machine.
- Measure the weights of the three bar specimens, using a digital electronic scale.
- Measure the diameters of the three specimens using the five methods described in step 2, and record the results of the non-corroded bar ....
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Results
Figure 6 shows the diameters of the 500 mm long non-corroded bar specimen at angles of 0°, 45°, 90°, and 135° for each section along its length measured using Vernier calipers. The bars were then cut into three parts, as shown in Figure 1.
Figure 7 presents the cross-sectional areas of the non-corroded bar specimens along its lengths measur.......
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Discussion
Figure 6A and 6B show that the measured diameters of the non-corroded bar specimen do not vary significantly along its length. The maximum difference between the measured diameters along the bar length is only about 0.11 mm with a maximum deviation of 0.7%. This indicates that the geometry of a non-corroded bar can be well evaluated using a Vernier caliper. However, the measured diameters at different angles of the same cross-section differ consistently and considerably from.......
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Disclosures
The authors have nothing to disclose.
Acknowledgements
The authors at Shenzhen University greatly acknowledge the financial support from the National Natural Science Foundation of China (Grant No. 51520105012 and 51278303) and the (Key) Project of Department of Education of Guangdong Province. (No.2014KZDXM051). They also thank the Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, College of Civil Engineering at Shenzhen University for providing testing facilities and equipment.
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Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| Supplies | |||
| Plastic ruler | Deli Group Co.,Ltd. | No.6240 | |
| white paint pen | SINO PATH Enterprises.,Ltd. | SP-110 | |
| Tube with Branch | Customized-made | ||
| Measurement cylinder | Beijing Huake Bomex Glass Co., Ltd. | ||
| 500mL Beaker | Beijing Huake Bomex Glass Co. , Ltd. | CP-201 | |
| sandpaper | Shanghai Noon Decoration Material Co., Ltd. | P04 | |
| white developer | SHANGHAI XINMEIDA FLAW DETECTION MATERIAL CO., LTD. | FA-5 | |
| Reagents | |||
| epoxy resin adhesive | Hunan Baxiongdi New Material Co., Ltd. | DY·E·44 | |
| epoxy hardener | Hunan Baxiongdi New Material Co., Ltd. | DY·EP | |
| HCl | Dongguan Dongjiang Chemical Reagent Co., Ltd. | AR-2500ml | |
| saturated lime water | Xilong Chemical Co., Ltd. | AR-500g | |
| Equipment | |||
| Digital electronic scale | Kaifeng Group Co., Ltd. | Model JCS-0040 | |
| Digital vernier caliper | Shanghai Measuring & Cutting Tool Works Co., Ltd. | Model ST-089-229-090 | |
| Cutting machine | Robert Bosch GmbH | TCO2000 | |
| 3D reconstructed X-ray microscope | XRADIA | Model MICROXCT-400 | |
| 3D scanner | HOLON Three-dimensional Technology(Shenzhen) Co.,Ltd. | Model HL-3DX+ | |
| Electromechanical Universal Testing Machine | MTS SYSTEMS (China) Co., Ltd. | Model C64.305 |
References
- Cavaco, E. S., Bastos, A., Santos, F. A. D. Effects of corrosion on the behaviour of precast concrete floor systems. Construction & Building Materials. 145, (2017).
- Cavaco, E. S., Neves, L. A. C., Casas, J. R. On the robustness to corrosion in the life cycle assessment of an existing reinforced concrete bridge. Structure and Infrastructure Engineering. 14 (2), 137-150 (2017).
- Muthulingam, S., Rao, B. N.
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