Looks like the chemicals and or salt they put on the sidewalk on affected the body of the sidewalk and not the borders. I wonder if it actually had a reaction with those brinks. Maybe Craigs new F9 effloresence is the trick. Not sure..

Do you have any close up pictures? Like Jim said not all appear to be having an issue. Are they all the same including the border areas?

they need to be power washed and then effloresces remover needs to be applied. The salt from the winter has left calcium on the paver and they may have there own calcium build up as well. Use can use the f9 calcium remover but any effloresces wash ( hydrophloric acid ) will do. Plus your will be saving just under $12-15 dollars per gallon.

Yeah dan Craig's new product should work with that I'm fixing to remove calcium stains from a brick home this weekened with Craig's new product. I'll have pics soon enough and I will let you know how it works!

Dan:
Ditto what Mike said.
EachoChem's OneRestore makes an efflorescence remover too, to might want to try out. I'd certainly do some test areas AND price shopping before I settled on just one product!

Efforesence is not calcium it is salt. Calcium deposits are not the same though both are readily confused and called effo all the time. There is a big difference. Calcium almost always requires manual agitation like a scraper to remove heavy deposits.

The white film seen on such stones is actually calcium carbonate, which is a byproduct of the reaction when cement is exposed to the environment.

Found this under a paver installers website.