Regarding new concrete. I asked a knowledgeable person who makes alpine troughs out of concrete. He said that it only takes one winter of rain for all the "stuff" to leach out and neutralize. At that point the concrete is a non-reactive substrate. He also said that he noticed no "dead zone" around the planters, so felt the leaching was easily handled by the surrounding soil. That said, if someone was putting in a huge slab or large waklway, a year of ground pollution might be another mater.
The lime in the concrete leaches out and raises the pH. My company has contracted landscape maintenance services to many apartments and strata complexes that have chlorotic acid soil loving plants. (yellow leaves) If it's a problem, ammend the soil the lower the pH. You can also spray iron chelate on the leaves and around the rootball. It will help.
A change of one pH point represents something like a thousand-fold increase or decrease in the level of acidity or alkalinity. Doing something to the soil that will change its pH even one point in a comparatively short period of time is quite disruptive to the soil community, a radical event. Existing plants will have to wait quite some time, during which the pH is gradually altered if treatments are not to be catastrophic at the microbiological level. Probably more useful and to the point to transplant existing unhappy plants away from the unsuitable positions, into suitable ones.
