She knows that salt should not be used.

 

Apparently she doesn't know as much as she thinks she knows.

Just why shouldn't salt be used on marble steps?

No good reason at all, she may have half read and retained less a newspaper article about salt use on roads.

The issue with salt, and I am specifically talking about NaCl, is that it increases the rate of corrosion of steel, specifically steel embedded in concrete.

Salt is one of the best deicers available.  Some of the other chemicals, such as MgCl, KAcetate, and NaAcetate, react with the minerals in concrete and cause different, and in all respects, more serious deterioration that requires removal of all of the concrete.

So, unless the marble steps are pinned together with ferrous pins, she should go ahead and use NaCl to deice the steps.

Before a citizen falls and breaks a hip, and then owns the building.

Or she falls herself, and the hospital owns the building.

 

Steve Stokowski