摘要
采用大板开裂方法制备了收缩裂缝宽度为0.07 mm、0.1 mm、0.2 mm、0.4 mm和0.62mm的混凝土试件,对养护7 d的不同尺度裂纹混凝土海水浸泡腐蚀30 d,以及快速碳化14 d。测试混凝土裂缝处及周边区域的碳化深度、自由氯离子及总氯离子浓度。试验结果表明:混凝土的自由氯离子与总氯离子均随裂缝宽度增加而呈二次函数增加。氯离子在裂缝处的迁移速度高于周边区域,但收缩裂缝尖端增加了氯离子结合能力,降低了自由氯离子浓度。当收缩裂缝宽度小于0.07mm,混凝土裂缝区域碳化深度没有变化。当收缩裂缝宽度小于0.1 mm,混凝土氯离子扩散系数与碳化深度增加幅度很小;此后,随裂缝宽度增加,混凝土氯离子扩散系数与碳化深度均快速增加。此外,混凝土裂缝处碳化深度比周边区域高3 mm左右。
The influence of shrinkage crack on chloride ion penetration and carbonation of concrete is investigated.The concrete samples with shrinkage crack of 0.07 mm,0.1 mm,0.2 mm,0.4 mm and 0.62 mm are prepared,and both an accelerated carbonation test and Qingdao sea water corrosion test are conducted on sound concrete and cracked concretes.The depths of carbonation,the content of free chloride and total chloride in crack zone and perimeter zone of concrete are analyzed.The enperimental result shows that both free chloride and total chloride content in cracked concrete increase with the rise of the shrinkage crack width,and they are related in quadratic function.The chloride penetration velocity in crack zone is higher than that in perimeter zone of concrete.However,the increased specific surface in shrinkage crack tip improves chloride binding capacity and decreases the free chloride content in this zone.When the shrinkage crack is less than 0.07mm,the carbonation depth in crack zone is same as that of sound concrete.The chloride diffusion coefficient and the carbonation depth of cracked concrete increase limited as the shrinkage crack is less than 0.1mm,and then increase significantly with the increasing of shrinkage cracked width.Moreover,the carbonation depth in crack zone is increased by 3mm in comparison with that in perimeter zone of cracked concrete.
出处
《土木建筑与环境工程》
CSCD
北大核心
2011年第1期7-11,共5页
Journal of Civil,Architectural & Environment Engineering
基金
国家自然科学基金项目(50708046
50739001)
山东省教育厅项目(J08LA04)
山东省自然基金(ZR2009FQ011
ZR1009FQ014)
国家"973"计划(2009CB623203)
关键词
混凝土
收缩裂缝
碳化
氯离子
concrete
shrinkage crack
carbonation
chloride
