What are the primary types of highway pavement?

The correct answer identifies the primary types of highway pavement as flexible pavement and rigid pavement. This classification is fundamental in highway engineering and construction.

Flexible pavement typically consists of layers of materials that can deform under load, with asphalt being a primary material used. Its design allows for the absorption of stresses and the ability to accommodate minor settlements in the subgrade without cracking. This feature makes it well-suited for various traffic conditions and climates, providing durability and a smoother ride.

On the other hand, rigid pavement is primarily composed of concrete, which provides a strong and durable surface. Its non-deformable nature means it does not flex under load, providing a stable driving surface. Rigid pavements are often preferred in areas subject to heavy traffic loads, as they can distribute loads over a wider area and typically require less maintenance over time compared to flexible pavements.

Other options like pervious and impervious pavement highlight specific characteristics regarding drainage but are not primary categories of highway pavement in the same way. Similarly, the terms thin and thick pavement relate more to the construction techniques and design philosophies rather than defining broad categories of pavement types. Thus, focusing on flexible and rigid pavement gives a clearer understanding of the essential types utilized in highway construction.