请教懂建筑方面的问题，看图，有谁知道刨开墙面的原因吗？

[屡敗屡战]

if found rust in the reinforced concrete structure. below is fix.
The traditional method of concrete repair is to remove the cracked and degraded concrete to a depth of 20 to 30 mm behind the reinforcing bars to fully expose the rusted reinforcement and move the contaminated concrete away from the steel. All corroded material is removed and the steel is either treated or replaced. Concrete repair mortars are then applied to the surface.

[最西边的岛上]

也可以去新建的“地坛”发帖问问：

https://bbs.wenxuecity.com/fdcj/

[蒼鷹]

问题，公寓管理层说今年修缮大楼外墙等，预算170万美元，住户分摊费用，管理费年收入约70万美元，缺口近百万美元。这里不谈钱，我发现有几个工人刨开原本坚如磐石的墙面，之后又补上，为什么？