List two methods for assessing the gradation of aggregate samples.

The correct choice for assessing the gradation of aggregate samples is sieve analysis and laser particle size analysis. Sieve analysis is a widely accepted method for assessing gradation, as it involves passing the aggregate through a series of sieves to separate the particles based on size. This method allows for a clear understanding of the distribution of different particle sizes within the aggregate sample and is foundational in determining whether the aggregate meets specified standards.

Laser particle size analysis, on the other hand, offers an advanced technique for measuring particle sizes. It utilizes laser diffraction to determine the size of particles as they pass through a laser beam, providing rapid and highly accurate measurements across a wide range of particle sizes. This technology complements traditional sieve methods by capturing finer particles that may be difficult to measure accurately with sieves alone.

These two methods together provide a comprehensive assessment of aggregate gradation, helping to ensure that the material meets the necessary specifications for construction applications. They are particularly useful for quality control and evaluating aggregate performance in various scenarios.