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3D cellular automata based numerical simulation of atmospheric corrosion process on weathering steel
Published in Nigel Powers, Dan M. Frangopol, Riadh Al-Mahaidi, Colin Caprani, Maintenance, Safety, Risk, Management and Life-Cycle Performance of Bridges, 2018
Weathering steels (WS) are increasingly used as engineering materials owing to environmental and economic advantages. The main applications of WS include bridges and other load-bearing structures, such as electricity posts, utility towers, guide rails and roofing, etc (Morcillo et al. 2013 & 2014). Protective rusts which form on the surface of WS at early stages can reduce further rusting. Therefore, WS can be used without painting or after rust stabilizing surface treatment. Being applicable to relatively mild environments such as rural and urban setting, these steels encounter difficulties in coastal areas because airborne salt deposits may generate porous and non-adhesive rusts on their surface (Nishikata et al. 2014). And when the steel structures are subjected to loads, such as bridges under vehicle loads, the protective rust layers may crack or even fall off. In these cases, the rust layers tend to lose protection, resulting in further corrosion of WS, especially pitting corrosion.
Repair of Reinforced Concrete Structures
Published in Mohamed Abdallah El-Reedy, Steel-Reinforced Concrete Structures, 2017
There are several regular steps in the repair of structures exposed to corrosion. The very critical first step is to strengthen the structure by performing structural analysis and designing a suitable location for the temporary support. The second step is to remove the cracked and delaminated concrete. It is important to clean the concrete surface and also the steel bars by removing rust. After rust is removed by brush or sand blasting, the steel bars should be painted with epoxy coating or replaced; then new concrete can be poured. The final step is to paint the concrete member for external protection. This is a brief description of the repair process. These steps are explained in detail in the following sections.
Non-destructive inspection of corroded steel bars in concrete structures
Published in Hiroshi Yokota, Dan M. Frangopol, Bridge Maintenance, Safety, Management, Life-Cycle Sustainability and Innovations, 2021
Reinforcing bars (rebar) placed in concrete structures have an extremely important role in load-carrying capacity. If the corrosion of the rebars progresses due to the neutralization or salt damage of concrete, cracks are induced, and the progress of the corrosion is accelerated, furthermore, the surface concrete may be peeled off (Kajikawa et al. (1990)). The corrosion damage of rebars can be found after rust juice has been revealed on the surface. In order to grasp the signs of rebar corrosion at an early stage and reflect it in the maintenance management plan, it is necessary to develop a non-destructive evaluation method to visualize the rebars in concrete to check the presence of corrosive damage.
Corrosion behaviour of carbon steel in Beibu Gulf tidal zone
Published in Corrosion Engineering, Science and Technology, 2023
Sheng He, Shiqi He, Peng Yu, Hongfei Li, Jingyong Feng, Pingfu Liao, Jianhui Liao, Xinheng Huang
Figure 4 presents the morphology of the matrix at different corrosion times after rust was removed. The size of etch pits gradually growing represents the deeper corrosion during the exposing process. The corrosion developed along the thickness direction of the specimen in the early stage (60 days – 120 days – 180 days), but with the accumulation of rust (240 days – 300 days – 360days), the corrosion was in the progress width direction. In addition, adjacent etch pits were interconnected into large etch pits forming the macroscopic corrosion on the local and surface of the steel. Above results denote that the pitting of CS occurs first in the tidal zone of Beibu Gulf and then evolves into uniform corrosion. The theory of the intrusion mechanism of chloride ions in passive film suggests that the mechanical stress of pores and impurities in steel is the main cause of passivation film failure [26]. Therefore, the local large corrosion pits in the matrix are caused by the destruction of the local passive film by the enriched Cl–. The matrix is continuously eroded, and the pits show a tendency of aggregation in the later stage of the test.
Ultra-low cycle fatigue properties and fracture mechanism of corroded structural steel
Published in Corrosion Engineering, Science and Technology, 2021
Fangyuan Song, Tingting Zhang, Xu Xie
The accelerated corrosion process was initiated by subjecting the specimens to neutral salt spray produced by a 5% sodium chloride solution. The salt spray was applied to the specimen for 10 min every 4 h and the chamber temperature was 30 ± 5°C. Each specimen in its entirety, except for the middle experiment segment, underwent antirust treatment. In this treatment, the specimen was painted with epoxy resin anticorrosive paint and then coated with Teflon tape (Figure 2) to ensure that the salt spray corroded only the middle segment. The degree of corrosion of the artificially corroded specimens was measured before testing. The epoxy paint was removed by an efficient paint-remover, which is non-corrosive of a metal substrate. Then the surface rust layer of the corroded specimens was cleaned away using 10% dilute hydrochloric acid mixed with 0.2% LAN-826 corrosion inhibitor at room temperature. Thereafter, the surface acid was neutralised by immersing the specimens into the saturated calcium hydroxide solution before washing and drying. Finally, the mass rate was calculated by weighing the steel specimens after rust removal.
Investigation of steel corrosion near the air–liquid interface in NaCl solution and soil environment
Published in Corrosion Engineering, Science and Technology, 2021
The collected soil was finely crushed and stirred manually, filled into a cylindrical container with diameter 202 and 400 mm depth. The soil surface was levelled by horizontally pressing, then fixed the steel pipe vertically into soil, as shown in Figure 6(b). The burial depth is more than 300 mm. The exposure test was conducted in the basement lasing for one year. To keeping the corrosive environment as constant as possible, the reduced weight of specimen caused by water evaporates was measured, and the pure water was supplied by spraying three times per week. For the tested specimen after exposure, the surface corrosion condition of the buried part was observed. The corrosion surfaces were measured using a 3D scanner (pitch: 0.2 mm) before and after rust removal. A chlorine-based cleaning agent used for removing the corrosion products from the steel pipe, and the cleaned surface was dried by acetone and blower.