Joints in rigid pavements – preventing compressive stresses Which type of joint is primarily provided in rigid concrete pavements to prevent the build-up of compressive stresses due to temperature rise and slab expansion?

Introduction / Context:
Concrete expands when heated and contracts when cooled. Because rigid pavements are restrained by adjoining slabs and friction at the base, thermal movements create stresses. Appropriate joints are installed to control these stresses and avoid cracking or blow-ups.

Given Data / Assumptions:

• Rigid pavement slab on subbase.
• Daily and seasonal temperature changes occur.
• We seek the joint that prevents compressive stress buildup.

Concept / Approach:
Expansion joints provide a gap (often with filler and sealant) that closes when the slab expands, thereby preventing compressive stress accumulation between slabs or at abutments. Contraction joints, by contrast, are intended to control tensile cracking on cooling by creating a weakened plane.

Step-by-Step Solution:
Identify stress type to be prevented → compressive stress during heating/expansion.Select joint that accommodates expansion → expansion joint.Therefore, the correct choice is expansion joint.

Verification / Alternative check:
Design standards specify spacing and widths for expansion joints in longer slabs or at fixed structures (bridges, culverts) to relieve compression.

Why Other Options Are Wrong:
Contraction joints address tensile stresses on cooling; hinged joints are structural detailing concepts and not the primary device for temperature compression relief in pavements.

Common Pitfalls:
Overusing expansion joints where contraction joints suffice; poor sealing leading to water ingress and pumping.

Final Answer:
expansion joint