裂缝、表面防水处理对混凝土耐久性的影响

混凝土结构普遍存在着大量的裂缝,在恶劣的环境条件下,一些裂缝成为侵蚀性离子进入混凝土的便捷通道,降低了混凝土的耐久性.侵蚀性离子如氯离子的传输离不开水的作用,如果混凝土表面和裂缝面的部分或者全部是斥水的,则可有效阻止氯离子的侵入.有机硅防水剂作为一种新型的防水剂,能够在混凝土的表层形成一个隔离层,实现减少氯离子侵入的目的.试验中所用的防水剂为有机硅液态防水剂.结果表明,从0.1mm到0.4mm的裂缝宽度范围内,不管防水处理是在裂缝出现之前还是之后进行,沿裂缝的氯离子含量都有大幅度的下降;同样宽度裂缝条件下,在裂缝出现之后进行防水处理,沿裂缝氯离子含量比先进行防水处理小一些.

Influence of cracks and surface water repellent treatment on penetration of chloride ion in concrete

There are a large amount of cracks in concrete structure,and many of these cracks have no influence on the structure.In a poor environment,the crack becomes a convenient channel for the corrosive ions penetrating into the concrete,which is harmful to the durability.The penetration of corrosive ions such as chloride ion relies on the transportation of water.If the cover of concrete and surface of part or whole crack is waterproof,then it's difficult for the chloride ion penetrating into concrete.As a new type of water repellent agent,silicon water repellent agent can form a barrier on the cover of concrete,for the aim to reduce the penetration of chloride ion.Liquid silicon water repellent agent is used in this experiment.The results show that,when the crack width ranges from 0.1mm to 0.4mm,whether the water repellent treatment is done before or after the appearance of cracks,there will be a large drop of chloride content along the crack.With the same crack width,when the water repellent treatment is done after crack's appearance,the chloride ion content along the crack is less than before crack's appearance.