AASHTO R 60:12(2020) Standard Practice for Sampling Freshly Mixed Concrete.
1.1. This method covers the procedures for obtaining representative samples of fresh concrete as delivered to the project site and on which tests are to be performed to determine compliance with quality requirements of the specifications under which the concrete is furnished (Note I). The method includes sampling from stationary, paving, and truck mixers and from agitating and nonagitating equipment used to transport central mixed concrete.
1 .2. The values stated in SI units are to be regarded as the standard. The inch-pound equivalents of metric units may be approximate.
Note 1—Combined samples are required by this method, unless specifically excepted by procedures governing the tests to be performed, such as tests to determine uniformity of consistency and mixer efficiency. Procedures used to select the specific test batches are not described in this method, but it is recommended that random sampling be used to determine overall specification compliance.
1 .3. This practice also covers the procedures to be used for preparing a sample of concrete for further testing where it is desirable or necessary to remove the aggregate larger than a designated size. This removal of larger aggregate particles is preferably accomplished by wet-sieving.
1 .4. The text of this standard references notes and footnotes that provide explanatory material and shall not be considered as requirements of the practice.
3. SIGNIFICANCE AND USE
3.1. This practice is intended to provide standard requirements and procedures for sampling freshly mixed concrete from different containers used in the production or transportation of concrete. The detailed requirements as to materials, mixtures, air content, temperature, number of specimens, slump, interpretation of results, and precision and bias are described in specific test methods.
4.1. The elapsed time shall not exceed 15 mm between obtaining the first and final portions of the composite sample.
4.1.1. Transport the individual samples to the place where fresh concrete tests are to be performed or where test specimens are to be molded. They shall then be combined and remixed with a shovel in the minimum amount necessary to ensure uniformity and compliance with the minimum time limits specified in Section 4.1.2.
4.1.2. Start tests for slump, temperatures, and air content within 5 mm after obtaining the final portion of the composite sample. Complete these tests quickly. Start molding specimens for strength tests within 15 mm after fabricating the composite sample. Quickly obtain and use the sample and protect the sample from the sun, wind, and other sources of rapid evaporation and from contamination.
5.1. Size of Samp/e—Make the samples to he used for strength tests a minimum of 28 L (1 ft3). Smaller samples are not prohibited for routine air content and slump tests and the size shall be dictated by the maximum aggregate size.
5.2. The procedures used in sampling shall include the use of every precaution that will assist in obtaining samples that are truly representative of the nature and condition of concrete sampled as follows.AASHTO R 60 pdf download.