For how long should material be sieved in accordance with C136?

The correct duration for sieving material in accordance with ASTM C136 is based on the performance goal of the sieving method. The standard specifies that a sample should be sieved until no more than 1% of the material passes through the sieve in one minute of hand sieving. This requirement ensures that the sieving process is efficient and that the material is adequately separated into different size fractions without unnecessary delays.

Achieving this threshold indicates that the majority of the material has been properly classified, allowing for a reliable analysis of the aggregates in the sample. The focus on a specific percentage passing helps maintain consistency and accuracy in testing, which is critical for quality control in construction materials.

Other timeframes, like sieving for at least 5 minutes, one hour, or until the last bit of material is separated, do not meet the criteria of ensuring efficiency combined with quality assurance as defined in C136. These options may lead to either insufficient separation or excessive time expenditure without guaranteeing better results.