When obtaining a sample from a roadway, how many increments should be taken prior to compaction?

When obtaining a sample from a roadway for Hot Mix Asphalt (HMA) evaluation, it is standard practice to take three increments prior to compaction. This practice ensures that the sample is representative of the entire batch or area being tested. By taking three increments, the potential variability within the mix can be captured, which provides a more accurate overall assessment of the material's properties.

Uniformity in sampling is crucial for quality control and assurance processes during construction. Increments should be taken from different locations to reduce the impact of any localized inconsistencies. This method also helps in achieving a more reliable average when analyzing the material's characteristics, such as gradation and asphalt content, which are essential for meeting performance specifications and ensuring durability in the final pavement.

On the other hand, taking fewer than three increments may not adequately reflect the mix's variability, leading to potential discrepancies in material evaluation and subsequent performance of the asphalt pavement. Therefore, three increments are recommended as a best practice for HMA sampling.