Q.: Is there a practical way to test air content on the job?
A.: The standard test for air content used by inspectors and testing laboratories is relatively easy to learn to do properly, and, once learned, it only takes a few minutes to make the test. Complete instructions are given in ASTM C 231, "Standard Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method," which appears in Part 14, 1981 Annual Book of ASTM Standards and also in Volume II of ASTM Standards in Building Codes. The Corps of Engineers, U.S. Army, publishes the same standard under its own designation "CRD-C 41-81," which appears in its Handbook for Concrete and Cement, Volume I.
An air test meter meeting the ASTM C 231 requirements can be purchased for somewhere in the range of $500 to $800 at current prices. If you are interested in acquiring and using one you should practice making the test on concretes that are being tested at the same time by a proficient and reliable operator. In this way you can learn to make the test accurately within the reasonable amount of operator error. Once you have learned to use the equipment properly you can make tests easily on the job and increase your confidence in knowing whether you are getting what you order.