Experimental study on the corrosion characteristics of anchor cable in alternating wet-dry environment

With the increasing number of corrosion failure cases of anchor cables being reported, significant attention has been drawn regarding their corrosion. Through case studies, it was found that steel strands near the anchor heads are more prone to corrosion failure. The primary reason is that these areas are in contact with the external environment, and due to grouting defects and other factors, water and air can enter, creating alternating wet-dry environment that lead to corrosion. To further investigate the corrosion characteristics of anchor cables under alternating wet-dry environment, a wet-dry alternating corrosion test for anchor cables was developed and conducted. The effects of the alternating period, number of wet-dry alternating, and NaCl concentration on corrosion were evaluated. The results showed that the weight loss ratio of anchor cables increased with the number of wet-dry alternating, and the longer the alternating period, the greater the weight loss ratio per alternating. The effect of NaCl concentration has an upper limit (approximately 1.00%). Below this limit, the weight loss ratio of anchor cables increases with higher NaCl concentration. However, once the concentration exceeds this limit, changes in NaCl concentration has no more influence. For environment with similar NaCl concentration, the weight loss ratio of anchor cables in alternating wet-dry environments was found to be 5 to 7 times higher than that in immersion environments. These results demonstrate the significant acceleration of corrosion under wet-dry alternating condition comparing to the immersion-based prediction models, and provide guidance for durability assessment and service life prediction of anchorage systems in aggressive environments.