Mike...generally, no. You do have to watch out for contamination such as other construction debris, pieces of rebar, etc......usually pretty minimal though.
Ask the supplier if they do any testing to make sure they're not getting concrete in that had deterioration problems such as Alkali-Silica reactivity. I doubt they test for it and it is only a problem in certain areas of the US and Canada, so if the concrete in your area generally gives good performance, then the recycled concrete likely will do the same given reasonable mix design and control.
Thanks for the info. I think the project may not be cost effective as the cost of hiring crushing equip and washing and grading concrete pieces for mix design will only be ok for large volumes.
