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Concrete on reinforcing

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Dear list,

I am looking for a reference that addresses cleaning off of concrete
buildup (i.e. from a previous pour) on exposed reinforcement prior to
subsequent pours.  ACI 301 5.7.2 and its sister language in the IBC are
the only references I have been able to find. They state "All
reinforcement, at the time concrete is placed, shall be free of mud, oil
or other materials that may adversely affect or reduce the bond."   

We have a job under construction where the contractor was not very
careful in placing or subsequent cleaning of the exposed reinforcement
or the cold joint (which is another issue).  As such, the majority of
the primary longitudinal reinforcement in the concrete grade beams is
currently gray with concrete of varying thickness based on photos
received from the special inspector.  I believe that this concrete
coating (for lack of better term) must be removed prior to placement of
the next pour.  My thoughts are that sand blasting is probably the only
means at this point that will sufficiently clean both the cold joint
surface and the concrete caked on the exposed reinforcement.

I would be interested in opinions from the list.

Thanks in Advance,

Jared F. Keyser, P.E.

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