Proper air entrainment improves the resistance of concrete to freeze/thaw exposure. Air content of concrete mixtures can be measured by procedures found in ASTM C231, “Standard Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method.” The equipment used to determine the air content of concrete mixtures containing relatively dense aggregate is performed using a Type B pressure meter. This eLearning course, Concrete Field Testing Grade I Certification Training – Testing for Air Content of Freshly Mixed Concrete by the Pressure Method, is available online at www.ACIeLearning.org. Certification by ACI is accomplished by successfully passing formal, proctored written, and performance exams administered by an approved ACI Local Sponsoring Group.