硅烷表面防水处理对钢筋混凝土横向裂缝区氯离子侵蚀的影响

Study on chloride penetration into the cracked zone of reinforced concrete and effect of water repellent treatment

钢筋混凝土结构在荷载作用下,常常是带(横向)裂缝工作的。裂缝的出现使结构由完好进入损伤状态,势必成为腐蚀介质迅速入侵的通道,大大影响了结构的耐久使用寿命。基于海洋环境条件,考虑结构往往持续承受外荷载的长期作用,开展了横向开裂钢筋混凝土的试验研究。详细分析了不同裂缝宽度、不同配合比试件横向开裂区的氯离子侵蚀状态,并进一步研究了开裂区硅烷防水处理的效果。研究表明,钢筋混凝土横向裂缝的存在对局部氯离子侵蚀有重要的影响,随裂缝宽度的增加裂缝区的氯离子含量有明显的增加;横向裂缝区氯离子侵蚀的范围受混凝土质量的影响程度远远超过裂缝宽度的影响;采用硅烷表面防水处理,可以有效减缓混凝土的氯离子侵蚀速度,降低裂缝区的局部氯离子含量,但由于渗入裂缝的防水剂有限,沿裂缝一定深度之后,防水效果逐渐减弱。

Concrete structures generally work under long term loads with limited transverse cracks,especially the reinforced concrete.The ap-pearances of cracks make structures into damage state.Then cracks will be the convenient channels for corrosive medium penetrating more quick-ly.Experimental studies on reinforced concrete with transverse crack are carried out with the long-term flexural loading in marine environment condition.Chloride penetrations in the transverse crack zone with different crack width and mix proportions are analyzed.And the effect of water repellent in crack zone is furthermore studied.Results show that the existing of transverse crack in reinforced concrete has important influence on local chloride penetration in crack zone.The content of chloride ions near the crack zone increases obviously with the crack width.In the transverse crack zone,the effect of the concrete quality on the scope of chloride penetration is larger than that of crack width.After surface treated with silane,chloride penetration is effectively reduced and local chlorine ion content is hereby reduced in crack zone.However,after a certain depth a-long the crack,waterproof affect gradually decreases caused by the limiting of silane penetration.