AASHTO T22:2014 Standard Method of Test for Compressive Strength of Cylindrical Concrete Specimens.
3.1. This test method consists of applying a compressive axial load to molded cylinders or cores at a rate that is within a prescribed range until failure occurs. The compressive strength of the specimen is calculated by dividing the maximum load attained during the test by the cross- sectional area of the specimen.
4.1. Care must be exercised in the interpretation of the significance of compressive strength determinations by this test method because strength is not a fundamental or intrinsic property of’ concrete made from given materials. Values obtained will depend on the size and shape of the specimen, batching, mixing procedures, the methods of sampling. molding, and fabrication, and the age, temperature, and moisture conditions during curing.
4.2. This test method may be used to determine compressive strength of cylindrical specimens prepared and cured in accordance with R 39, T 23, T 24M/T 24, T 231, and ASTM C873/C873M.
4.3. The results of this test method may be used as a basis for quality control of concrete proportioning, mixing, and placing operations: determination of compliance with specification; and control for evaluating effectiveness of admixtures and similar uses.
5.1. Testing Machine—The testing machine shall be of a type having sufficient capacity and capable of’ providing the rates of loading prescribed in Section 7.5.
5.1.1. Verify calibration of the testing machines in accordance with ASTM E4, except that the verified loading range shall be as required in Section 5.3. Verification is required under the following conditions:
5.1 .1 .1. At least annually but not to exceed 13 months; On original installation or immediately after relocation:
5.1 .1 .3. Immediately after making repairs or adjustments that affect the operation of the force applying system or the values displayed on the load indicating system, except for zero adjustments that compensate for the mass (weight) of tooling or specimen, or both; or Whenever there is reason to suspect the accuracy of the indicated loads.AASHTO T22 pdf download.