In civil engineering, a road pavement structure is designed to withstand the various loads and environmental conditions experienced by roads over their lifespan. A typical road pavement structure consists of several key components, each serving a specific purpose to ensure the durability, safety, and longevity of the road. These components include:

Surface Course:

The surface course, also known as the wearing course or asphalt layer, is the topmost layer of the pavement structure.

It provides a smooth and skid-resistant surface for vehicles to travel on.

The surface course is made of asphalt concrete (commonly known as asphalt or bitumen) or concrete, depending on the design specifications and traffic conditions.

Binder Course:

Below the surface course is the binder course, which acts as an intermediate layer between the surface course and the base course.

The binder course helps to distribute loads evenly across the pavement structure and provides additional structural support.

It is typically made of a coarser asphalt mix compared to the surface course.

Base Course:

The base course is situated beneath the binder course and serves as the main structural component of the pavement.

It provides additional strength and stability to the pavement structure by distributing the load from traffic to the underlying subgrade.

Common materials used for the base course include crushed stone, gravel, or recycled materials like asphalt or concrete.

Subbase Course:

The subbase course is located beneath the base course and serves to improve the load-bearing capacity of the pavement structure.

It helps to distribute loads over a larger area and prevent the deformation of the underlying subgrade.

Subbase materials may include granular materials like crushed stone, gravel, or stabilized soil.

Subgrade:

The subgrade is the natural soil or prepared earth foundation upon which the entire pavement structure rests.

It provides support to the overlying pavement layers and must be properly compacted and graded to withstand the anticipated loads.

Subgrade soils are often treated or stabilized to improve their strength and prevent moisture infiltration.

Fill in the blank question:

The surface course, also known as the wearing course or asphalt layer, provides a smooth and skid-resistant surface for vehicles to travel on. It is typically made of ---------- or concrete.

A) Gravel B) Asphalt C) Sand D) Soil