Rutting caused by asphalt surface issue is associated with which conditions?

• A. Low voids, excess sand, excess asphalt.
• B. Insufficient compaction
• C. Weathering of the entire surface
• D. Route and seal

Answer: (A)

Rutting is permanent deformation in the wheel paths that happens when the asphalt mix yields under repetitive traffic, especially as temperatures rise and the binder softens. When the mix has low voids, it’s very dense and the internal pathways for shear and rearrangement are limited, so the aggregates and softened binder tend to creep in the direction of traffic, forming longitudinal ruts. If there is extra asphalt binder, the mixture loses stiffness and can flow more easily under loading, amplifying the deformation that creates ruts. Excess fines like sand can disrupt the aggregate skeleton and lubricate contacts between particles, reducing resistance to shear and allowing more deformation to accumulate in the wheel paths. Put together, these conditions make the pavement more susceptible to rutting, particularly under hot-weather traffic.

Insufficient compaction would leave more air voids, which changes durability and susceptibility to moisture damage rather than directly causing rutting. Weathering of the entire surface leads to surface wear, cracking, or deterioration rather than the persistent deformation of rutting. Route and seal isn’t a standard cause of rutting, which is about deformation under load rather than surface texture or treatment issues.