Name the standard used for determining the compressive strength of concrete.

The correct choice is ASTM C39, which is the standard test method for the compressive strength of cylindrical concrete specimens. This standard provides a detailed procedure for testing the compressive strength of concrete cylinders, typically prepared in the laboratory or in the field. It outlines the necessary equipment, the process for preparing the specimens, and the conditions for curing them prior to testing.

The significance of ASTM C39 lies in its role in ensuring the quality and performance characteristics of concrete used in construction projects. By following this standard, engineers and inspectors can ensure that the concrete meets specific strength requirements, which is crucial for the safety and durability of structures.

The other options pertain to different aspects of testing or materials. For instance, ASTM C90 focuses on the specification for loadbearing concrete masonry units, ASTM D75 covers sampling aggregates, and ASTM E83 addresses the calibration of force-measuring instruments used in testing. Each of these serves a specific purpose but does not relate to the direct measurement of compressive strength in concrete, which is why they are not the appropriate answer for this question.