Under AGCS, how can the gradation of aggregates be adjusted?

The correct answer is based on the understanding of gradation adjustments and their relationship with the physical characteristics of aggregates. Adjusting the gradation of aggregates can significantly impact the performance of a mixture.

Changing non-critical sieve settings allows for flexibility in achieving the desired gradation without affecting the overall performance of the aggregate mix. Non-critical sieves are those that do not have strict requirements set by specifications, and therefore, modifications to their settings can help tailor the gradation curve to meet specific performance criteria. This method retains the essential properties of the aggregate while fine-tuning the mixture to optimize workability, strength, and durability.

In contrast, the other options do not directly pertain to the adjustment of gradation in the context of aggregate mixtures in the same effective manner. Increasing the quantity of fine aggregates could impact the overall gradation but might not provide the necessary adjustments for specific performance characteristics. The addition of chemicals primarily pertains to enhancing properties like adhesion or workability rather than directly modifying gradation. Lastly, using a different type of aggregate alters the baseline characteristics of the mixture, which might not be practical for adjusting gradation specifically for a given project.