What is the primary function of the base layer in pavement structures?

The primary function of the base layer in pavement structures is to provide structural support and distribute loads to the subgrade. This layer serves as a critical component in maintaining the integrity of the pavement by distributing the weight of vehicles and preventing excessive stresses on the underlying soil.

By having a robust base layer, the pavement can handle traffic loads effectively, minimizing deformation and prolonging the lifespan of the road. This support is essential because the subgrade, which is the layer of soil beneath the pavement, may not be capable of bearing heavy loads on its own.

The other options presented, while relevant to different aspects of road construction, do not pertain to the primary role of the base layer. Insulation against temperature changes or reducing noise pollution are concerns that may be addressed through other materials or design strategies. The aesthetic appearance of the road is also generally influenced by surface treatments and finishes rather than the base layer.