ASTM C39 | Concrete Cylinders | Compression Testing
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.
A testing machine, capable of providing the load rates as prescribed in the standard should be equipped with two steel bearing blocks, one of which is a spherically seated block that will bear on the upper surface of the specimen, and the other a solid block on which the specimen will be placed on. Before conducting ASTM C39, it is important to read the entire specification in the relevant ASTM publication.
ASTM C39 | Concrete Cylinders | Compression Testing
- Place the specimen on the lower bearing block so the axis of the specimen is aligned with the center of thrust of the spherically seated bearing block.
- Make sure the load indicator is set to zero prior to starting the test.
- Apply a compressive load of 35 ± 7 psi/s (0.25 ± 0.05 MPa/s) continuously and without shock until failure or until the operator is certain that the ultimate capacity has been achieved.
- Record the maximum load carried by the specimen during the test and note the type of fracture pattern.
- Compressive Strength
- Density (optional)
ASTM C39 | Concrete Cylinders | Compression Testing
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