Pavement Design MCQ with answer and solution

Concept

In expansion joints of concrete pavements, dowel bars transfer wheel load across the joint.

Step-by-step solution

1. An expansion joint is a full-depth gap that lets the slab expand. 2. Aggregate interlock cannot work because the slabs are separated by a gap. 3. Plain round dowel bars are placed across the joint. One end is free to slide. 4. Dowel bars carry the load from one slab to the next and still allow movement. 5. So the answer is (C) dowel bars.

Explanation

Expansion joints have a wide gap, so the slabs do not touch each other. Smooth dowel bars bridge this gap and transfer load, while allowing the slab to expand and contract. Tie bars are used in longitudinal joints, not expansion joints.

Why the other options are wrong

A: Tie bars are deformed bars in longitudinal joints. They hold slabs together and do not allow movement. B: Longitudinal bars are slab reinforcement, not joint load-transfer devices. D: Aggregate interlock works only in tight contraction joints, not in a wide expansion gap.

Shortcut

Dowel = load transfer + movement allowed. Tie bar = holds slabs together.

Common mistake

Confusing tie bars (longitudinal joints) with dowel bars (transverse expansion and contraction joints).