Hi Apex, the use of chemicals/acids would probably not be advisable primarily because of the potential for exposure to the workers and the public and secondarily because of the time it would take to dissolve the concrete. Mechanical demolition of concrete is the best way to salvage reinforcing rod from the concrete. Jaw crushers are the best way to do this as they will clean the rebar as the concrete is sized down to more manageable size. The next best hing is to use a hydraulic hammer to crack the concrete; thus sizing it and separatin git form the rebar. Similarly, other types of force applied methods will work (ie: dropping the concrete, using hand tools).
I do know Stanley-LaBounty has dealers in Malaysia and Thailand. they manufacture these types of machines. You can find them on the web at Stanley Works - Hydraulic Tools.
I hope this helps!