EFFECTS OF SUSTAINED LOADING CRACKS AND ARTIFICIAL CRACKS ON CHLORIDION DIFFUSION AND SERVICE LIFE PREDICTION UNDER FREEZE-THAW EROSION CYCLES
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摘要: 寒冷沿海环境或除冰盐环境的钢筋混凝土(RC)结构受到荷载裂缝与冻融氯腐蚀的综合作用。氯离子易通过裂缝快速侵入混凝土并腐蚀钢筋,缩短RC结构的服役寿命。对带有人工裂缝和持续荷载裂缝的RC试件进行冻融循环和氯溶液侵蚀综合作用,研究持续荷载裂缝和人工裂缝下氯离子扩散性及服役寿命差异。持续荷载裂缝宽度分别为0,0.06,0.07,0.11,0.13 mm,人工裂缝宽度分别为0,0.07,0.13,0.19 mm。研究结果表明:裂缝宽度小于0.07 mm时,持续荷载裂缝和人工裂缝对氯离子扩散性的作用差别很小;裂缝宽度大于0.07 mm时,持续荷载裂缝对氯离子扩散性作用大于人工裂缝的作用,且随着裂缝宽度增加,两者差异快速增大。分别考虑氯离子一维扩散和二维扩散状态,利用Monte-Carlo法计算得到的RC结构的服役寿命中,持续荷载裂缝的RC结构预测寿命明显低于人工裂缝。Abstract: The reinforced concrete (RC) structures in cold coastal regions or deicing salt condition were under the synthetic effects of loading cracks and corrosion led by freeze-thaw and chloride ingress. The steel was vulnerable to chloridion ingress because the crack provided convenient channel, which shortened the service life of RC structures. The chloridion profile of RC specimens with sustained loading cracks and artificial cracks after being subjected to the combined action of freeze-thaw and chloridion immersion was experimentally studied. This study focused on the difference between the effects of sustained load cracks and artificial cracks on chloridion diffusion and service life. In this study, the widths of sustained loading cracks were 0,0.06,0.07,0.11,0.13 mm and the widths of artificial cracks were 0,0.07,0.13,0.19 mm. The experimental results showed that, when the crack width was less than 0.07 mm, the differences between the effects of sustained loading cracks and artificial cracks on chloridion diffusion were slight. When the crack width was more than 0.07 mm, the effects of sustained loading cracks on chloridion diffusion was larger than that of artificial cracks. In addition, the differences became bigger as the crack width increased. The chloride diffusion in one-dimensional and two-dimensional state were respectively considered. The service life was predicted by Monte-Carlo Method. It was obvious that the service life of RC structures with sustained loading cracks was shorter than that with artificial cracks.
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Key words:
- reinforced concrete /
- freeze-thaw cycle /
- crack width /
- chloridion diffusion /
- service life prediction
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