Pavement Design MCQ with answer and solution

Concept

Flexible Pavement Layer Sequence

Formula

No formula

Step-by-step solution

- Identify the layers of flexible pavement from top to bottom: Bituminous layer, Base layer, Subbase layer, and Subgrade. - Compare this sequence with the given options. - Option C correctly matches this sequence.

Explanation

Option C is correct because flexible pavements are built in distinct layers, placed from the strongest material at the top to the natural foundation at the bottom: - Bituminous layer (Top): The uppermost driving surface made of asphalt/bitumen that resists vehicle wear and protects lower layers from rainwater penetration. - Base layer: Positioned directly under the bituminous surface to carry and spread heavy traffic loads. - Subbase layer: Located beneath the base layer to provide additional structural support and drainage while preventing subgrade soil from mixing into upper layers. - Subgrade (Bottom): The lowest layer consisting of compacted natural soil that acts as the foundation for the entire pavement structure.

Shortcut

Use the acronym/mnemonic B-B-S-S (Top to Bottom): - Bituminous layer (Surface) - Base layer - Subbase layer - Subgrade (Foundation/Bottom)·Memory Tip:* Remember Big Boys Stand Strong. Surface layers are Base-type, while underground layers start with Sub.

Common mistake

A common mistake is confusing the relative order of the base layer and subbase layer (selecting Option D instead of C) or mixing up the top-to-bottom sequence with the bottom-to-top construction sequence.