It's been about 9 years since initial steps were outlined for employing performance-based concrete specifications in U.S. practice. Initial progress was promising, as only about 2 years passed before ACI Committee 318, Structural Concrete Building Code, approved durability exposure categories for concrete. In this month's CI, however, contributors Karthik Obla and Colin Lobo report that practical execution of performance-based project specifications has been limited (p. 29). This lack has prompted the Research Engineering and Standards committee of the National Ready Mixed Concrete Association (NRMCA) to produce its Specification in Practice (SIP) series: brief write-ups that pose alternative performance criteria for commonly used prescriptive requirements. SIPs covering five specification items are published in this issue (sec p. 48).
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