Sources: National Ready Mixed Concrete Association, Silver Spring, Md.
NRMCA staff participating in ASTM C09 committee meetings last month in Indianapolis cite two significant Subcommittee C09.40 Ready Mixed Concrete actions for the C94 standard: removal of the 300 value and a new resolution process for low strength test results.
Under the revised standard, ready mixed concrete producers or purchasers maintain the option of stipulating a threshold for mixer truck drum revolutions as part of their own quality control targets. The second major ASTM C94 change suggests ready mixed concrete producer and purchaser confer to reach an agreement in response to the variations between specified and delivered product compressive strengths.