Overview of ASTM C138 - Standard Test Method for Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete.

This is a test required to pass the American Concrete Institute (ACI) Field Technician Certification Program -- "Concrete Field Testing Technician—Grade I." A Concrete Field Testing Technician—Grade I is an individual who has demonstrated the knowledge and ability to properly perform and record the results of seven basic field tests on freshly mixed concrete.

The program requires a working knowledge of the following ASTM test methods and practices:

● C1064/C1064M - Temperature of Freshly Mixed Hydraulic-Cement Concrete
● C172 - Sampling Freshly Mixed Concrete
● C143/C143M - Slump of Hydraulic-Cement Concrete
● C138/C138M - Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete
● C231 - Air Content of Freshly Mixed Concrete by the Pressure Method
● C173/C173M - Air Content of Freshly Mixed Concrete by the Volumetric Method