Which statement is true about gradation analysis after removal from baskets?

• A. It is performed before removal
• B. It is performed after removal using AASHTO T 37
• C. It is performed after removal in accordance with AASHTO T 30
• D. It is not performed

Answer: (C)

Gradation analysis is done on the aggregate after the asphalt binder has been removed, so you’re measuring the actual size distribution of the mineral particles without the masking effect of the binder. When you recover a sample from the plant and remove the binder, you then perform sieve analysis exactly as specified for bituminous mixtures. AASHTO T 30 provides that procedure, ensuring the results reflect the true gradation of the aggregate used in the mix. Doing the analysis before removing the binder would mix in the binder and alter the apparent particle sizes, leading to an inaccurate gradation. Using the standard for bituminous mixtures after binder removal gives you a consistent, valid measure of the aggregate’s gradation.