What is the recommended method for representing samples in aggregate testing?

Quartering is the recommended method for representing samples in aggregate testing because it effectively reduces a larger sample to a manageable size while maintaining the original material's characteristics. This method involves dividing the sample into four equal parts and then taking a diagonal combination of two opposite quarters, discarding the other two. This technique minimizes the risk of sample bias or inconsistencies, which can arise from improper handling or sampling.

In aggregate testing, ensuring a representative sample is critical for obtaining accurate test results that reflect the overall properties of the material. Quartering effectively preserves the distribution of different aggregate sizes and types within the sample, allowing for reliable testing outcomes that can inform decisions about material quality, suitability for use, and performance in construction applications.

Other methods like mixing, rotating, or compacting do not serve this purpose as effectively. Mixing may alter the distribution of the aggregate and introduce variability, rotating does not reduce the sample size or ensure representativeness, and compacting is related to the density and structure of the sample rather than its representativeness. Thus, quartering stands out as the appropriate choice for accurate sampling in aggregate testing.