It would be unrealistic to try and explain details of the chemical compounds used in preventing concrete damage in a single paragraph.

So we will state the causes first,

Generally two reasons, first if a concrete pour was late year, it may have froze prior to curing. Freezing will reduce  tensile strentgh of  concrete to about a 3rd of its rating.

Another cause of concrete damage is a bad pour the mix,the float, air inside the concrete leaving a porous set, water enters, freezes and pop.

A third cause that is often debated between concrete installers and Ice melt crews is the effect the chemicals in the De-Icer have on the surface of the concrete.

The remedy, apply a densifier and top sealcoat to the surface of the concrete. This will harden the concrete as well as seal  any voids in the concrete keeping water out.