No de-icer is perfectly safe for concrete. Why? Because you are melting ice while the general temperature is below zero, allowing both water and some kind of chemical to flow into the concrete itself and refreeze shortly after. De-icers should not be used on new concrete -- wait until it is at least one year old and it has been treated with a sealer to reduce the amount of salt that can penetrate the surface.
But before I get to the De-Icers, let me talk about a new kid on the block -- the ice that is simply not slippery -- Eco-Ice Grip. This is simply softwood wood chips with just the right mix of magnesium chloride to help the chips to melt into and stick on the ice - making the safest icy walkway I ever walked on. This has the lowest ecological impact and the greatest degree of safety for walkways. Get more details here.
But that said there will be times when you want to remove ice, or can't find the Eco-Ice grip chips and some de-icers are harder on concrete than others. Any actually containing common salt (sodium chloride - NaCl), can potentially do the most damage, because the salt can form crystals within the concrete that will expand and pop off the upper layer of the concrete. Ones based on fertaliser or on Calcium Chloride (CaCl2) do the least damage, because they are organic and don't form a crystalline structure when they dry. (Xynyth is a Canadian made organic deicer) I have received one important caution from Lorraine living in Waukesha Wisconsin. She confirms that fertilizer does melt snow, but can make a dog who eats snow very sick, if not kill it. Hence don't use it if you have snow eating animals.
Remember that any de-icer that comes in large chunks is designed to penetrate through the ice, honeycomb it and help in its removal. More powdery style de-icers and sand are designed to sit on top of the ice and give you traction. For any given space, you may need one, the other or both.
If you have harsh chemicals or salts in your de-icer, be careful about piling too much of it up on your lawn. All that salt will eventually melt into the grass, and plants don't like salt very much. On the other hand, piling up the Urea based de-icers within reason can actually fertilise that lawn.