Corrosion Prediction of Coated Steel in Magnesium Cement Concrete Based on Wiener Degradation
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摘要: 镁水泥混凝土对钢筋的腐蚀限制了其广泛的推广应用,为解决这一难题,提出利用涂层来缓解其对钢筋的腐蚀,确保镁水泥钢筋混凝土建筑满足设计规定的使用年限要求. 根据西部盐渍土地区的自然环境,采用溶液浸泡加速锈蚀的试验方法对氯氧镁涂层钢筋混凝土进行快速腐蚀试验;运用电化学工作站周期性地对氯氧镁涂层钢筋混凝土试块进行电化学试验;以表征涂层钢筋锈蚀的电化学参数(腐蚀电流密度)作为退化指标,在Wiener退化过程的基础上进行可靠度建模并且对涂层钢筋进行锈蚀预测. 研究结果表明:利用涂层钢筋腐蚀电流密度作为耐久性退化指标可以得到镁水泥涂层钢筋混凝土中的涂层钢筋锈蚀的可靠度函数,并确定出涂层钢筋在30 000 d左右达到中等腐蚀.
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关键词:
- 镁水泥混凝土 /
- 腐蚀电流密度 /
- Wiener退化过程 /
- 可靠度 /
- 锈蚀
Abstract: The corrosion of magnesium cement concrete on steel bars limits its widespread application. To solve this problem, coating is proposed to alleviate the corrosion of steel bars and ensure that magnesium cement-reinforced concrete buildings meet the design requirements over their service life. Based on the natural environment of the Western saline soil area, a rapid corrosion test of magnesium oxychloride-coated reinforced concrete was performed using the solution immersion accelerated corrosion test method. Electrochemical tests of magnesium oxychloride-coated reinforced concrete were periodically conducted using an electrochemical workstation. The electrochemical parameter of corrosion current density, which characterises the corrosion of a coated steel bar, was used as the degradation index; then, a reliability model was built on the basis of the Wiener degradation process, and the corrosion of a coated steel bar was predicted. The results show that the corrosion reliability function of a steel bar coated with magnesium cement-reinforced concrete can be obtained by using the corrosion current density as a durability degradation index, and the coated steel bar reaches moderate corrosion at approximately 30 000 d. -
表 1 镁水泥混凝土配合比
Table 1. Mixing proportion of magnesium oxychloride cement concrete
kg/m3 氧化镁 减水剂 抗水剂 砂 碎石 氯化镁 水 388.96 2.288 1.601 6 625 1 162 147.811 135.586 表 2 钢筋腐蚀电流密度和锈蚀程度之间的对应关系
Table 2. Relationship between corrosion current density and corrosive degree of rebars–2
μA/cm2 无锈蚀 低腐蚀 中等腐蚀 严重腐蚀 icoor < 0. 1 0. 1≤icoor < 0. 5 0. 5≤icoor < 1.0 icoor≥1.0 表 3 涂层钢筋的电化学参数
Table 3. Electrochemical parameters for a coated steel bar
×10–8A/cm2 项目 0 d 90 d 180 d 270 d 360 d 450 d 540 d 630 d 720 d 810 d 900 d 990 d 电流密度 0.112 5.660 4.420 3.780 4.060 3.590 4.430 4.850 4.050 3.520 4.100 4.500 增量 0.055 5 – 0.012 4 – 0.006 4 0.002 8 – 0.004 7 0.008 4 0.004 2 – 0.008 – 0.005 3 0.005 8 0.004 0 表 4 裸钢的电流密度
Table 4. Current density of a bare steel bar
μA/cm2 0 d 90 d 180 d 270 d 360 d 450 d 540 d 630 d 720 d 810 d 900 d 990 d 0.095 5.800 5.500 5.900 5.400 5.100 4.960 5.300 5.300 5.100 5.900 6.400 -
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