ASTM C39 / C39M - 16b
Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens

ASTM C39 determines the compressive strength of cylindrical concrete specimens such as molded cylinders and drilled cores. It is limited to concrete having a unit weight in excess of 50 lb/ft3 (800 kg/m3).

A compressive axial load is applied to molded cylinders or cores until failure occurs. The compressive strength of the specimen is calculated by dividing the maximum load achieved during the test by the cross-sectional area of the specimen. The results of this test method are used as a basis for quality control of concrete.

Cylinders cast and cured in the field are transported to the laboratory within 24-to-48 hours of production. Cylinders are then cured in water (or high-humidity chamber) for the specified curing period (e.g., 7-days, 28-days, etc.). On the date the cylinder has cured for the specified period of time, the cylinder is removed from the water tank and tested in compression with strength and failure mode reported.

Preferred Test Sample Size:
Typically 4" x 8" or 6" x 12" cylinders

Number of Test Specimens:
3 but typically several specimens per set of cylinders

   

refer Concrete Compressive Strength Testing Machine.