干湿循环对混凝土单面盐冻破坏的影响

The Effect of Dry-wet Circulation on One-sided Salt Frost Damage of Concrete

采用冻融循环、冻融-干湿循环的试验方法,研究了混凝土单面浸泡在1%、3%、5%、7%、9%浓度氯化钠溶液中的离子扩散及抗冻融性能,系统讨论了干湿循环对混凝土单面盐冻破坏的影响。结果表明:与单一的冻融循环过程相比,干湿循环加剧了冻融循环过程中混凝土内部氯离子的扩散作用,并产生更大单面盐冻剥落。在干湿循环作用下,混凝土内部氯离子富集区由2.5~12.5mm扩大到2.5~17.5mm;在破坏最严重的3%浓度组中,混凝土单面盐冻剥落量从冻融循环的1 501.3g/m^2提高至冻融-干湿循环的2 402.08g/m^2,相对动弹性模量下降量从冻融循环的22%提高至冻融-干湿循环的28%。在冻融-干湿循环实验中,冻融破坏起着主要作用,干湿循环剥落量不足冻融剥落量的2.5%。

Using freeze-thaw circulation method along with freeze-thaw and dry-wet circulation method, this paper studied the diffusion of chloridion and anti-frost performance of concrete soaked in sodium chloride solution （1 %, 3%, 5 %, 7%, and 9 % concentration）, and ystematically discussed the influence of dry-wet circulation to the one-sided saltfrost damage of concrete. The test results show that dry-wet circulation intensifies the diffusion of chloride ions and increases the one-sided salt frost scaling during freeze-thaw circulation. Under the influence of dry-wet circulation, the enrichment region of internal chloride ion expands from 2.5-12.5 mm to 2.5-17.5 mm; the one-sided salt-frost scaling amount increases from 1 501.3 g/m2 to 2 402.08 g/m2 , and the relative dynamic modulus of elasticity＇ s decreasing amount grows from 22% in single circulation to 28% in compound circulation. In the compound circulation, freeze-thaw damage plays a major role, and the scaling amount generated during dry-wet circulation only equals to 2.5% of that in freeze-thaw circulation.