摘要
沿海环境下钢筋混凝土梁是带裂缝工作的,裂缝为氯离子、氧、水等介质提供了通道,易引起钢筋过早锈蚀,降低结构使用寿命。试验研究了不同初始裂缝宽度(0、0.04、0.07、0.09、0.12 mm)的钢筋混凝土梁,经历不同时间海水干湿循环后的裂缝发展及氯含量变化。结果表明,混凝土梁裂缝表面均呈现显著的自愈合现象,但是裂缝宽度大于等于0.09 mm时,尽管裂缝表面愈合较好,裂缝内部宽度仍较大;裂缝宽度小于0.09 mm时,随距离表面深度增加氯含量降低且各裂缝宽度梁的保护层内氯含量差异不大;当裂缝宽度大于等于0.09 mm时,随距离表面深度增加氯含量降低但保护层内氯含量差异明显增大;在干湿循环时间大于96 d时,混凝土氯含量呈现加速趋势,其中裂缝宽度小于0.09 mm时增速较缓,裂缝宽度大于等于0.09 mm时增速显著;钢筋表面混凝土氯含量随干湿循环时间增加而不断累积,且随裂缝宽度增加而增大,干湿循环96 d和裂缝宽度0.09 mm是钢筋表面混凝土氯含量显著增加的综合界限。
Reinforced concrete structures work with cracks in coastal environment.Cracks provide channels for chloride,oxygen,water and other media,which contribute to the premature corrosion of steel and declined service life of structures.The reinforced concrete beams with different crack widths（0,0.04,0.07,0.09 and 0.12 mm）experiencing different seawater wet-dry cycles was tested.The development of crack widths and the variation of chloride ion content were compared between beams with different initial crack widths and different duration time.The results showed that all the cracked concrete had good self-healing phenomenon in surface,and when the crack width was greater than or equal to 0.09 mm,although the surface of the concrete crack self-healing was obvious,the inner concrete did not heal.When the crack width was less than 0.09 mm,with the increasing of concrete depth,the chloride content in concrete decreased,and chloride contentin concrete coverof beams with different crack widths had small difference.When the crack width is greater than or equal to0.09 mm,it increased obviously.When the exposure time wasmore than 96 d,the chloride content in the concrete increased faster,and when the crack width was less than 0.09 mmit increased relatively slowly while the crack width is greater than or equal to 0.09 mm it increased relatively sharply.The content chloride in concrete of the surface of steel increased with the increasing of dry-wet cyclesand the crack width.Duration time 96 d and crack width 0.09 mm were the comprehensive limits of the chloride content in concrete of the surface of steel.
出处
《混凝土》
CAS
北大核心
2017年第11期13-18,共6页
Concrete
基金
国家自然科学基金(51678021)
亚热带建筑科学国家重点实验室开放课题(2016ZA03)
关键词
钢筋混凝土梁
裂缝宽度
暴露时间
干湿循环
氯含量
reinforced concrete beam
crack width
duration time
wet-dry cycle
chloride content
