What is a characteristic of Stone Matrix Asphalt (SMA)?

Stone Matrix Asphalt (SMA) is characterized by gap grading, which is a specific gradation design that is used to achieve its unique properties. In gap-graded mixes, certain sizes of aggregates are excluded from the gradation, resulting in a mix with a higher proportion of coarse aggregates compared to fine aggregates. This design allows for improved stability and durability in the resulting asphalt concrete, which is essential for accommodating high traffic volumes and heavy loads.

The gap grading in SMA contributes to its increased resistance to permanent deformation (rutting) and its ability to maintain a durable surface even in harsh conditions. This makes SMA a popular choice for roadways that experience significant stress and wear. Moreover, the voids created in the aggregate structure facilitate better drainage, reducing the risk of moisture-related damage.

In contrast, the other options do not accurately describe the defining characteristics of SMA. While fine grading, standard asphalt binder, and low viscosity may pertain to different performance criteria of various asphalt mixes, they do not align with the specific properties of SMA that make it stand out in asphalt technology. The emphasis on gap grading in SMA is essential for ensuring its structural integrity and performance in various applications.