A complex issue that often arises on a concrete construction project is where to test the fresh concrete--at the point of discharge or the point of placement? And who is responsible for ensuring that the as-placed concrete meets specification requirements?
Section 4.3.2 of both ACI 301-96 and 301-99 requires the concrete supplier to deliver concrete that will possess the specified fresh-concrete properties at the point of placement. But sections 22.214.171.124 and 126.96.36.199 of these documents require testing for slump and air content at the point of delivery. ASTM C 94–98b, "Standard Specification for Ready-Mixed Concrete," indicates that the supplier should deliver concrete in compliance with the specification at the point of discharge from the mixer.
Concrete Construction asked Dick Gaynor, a consultant and past technical director of the National Ready Mixed Concrete Association, and Timothy Moore, an engineer with San Diego Gas & Electric and past chair of ACI 301, to comment on point of testing and the responsibilities of the parties involved.