Which statement best describes contraction joints and expansion joints in concrete pavements?

Which statement best describes contraction joints and expansion joints in concrete pavements?

• A. Contraction joints prevent thermal expansion; expansion joints prevent shrinkage cracks.
• B. Contraction joints control cracking due to shrinkage; expansion joints accommodate thermal movement between slabs.
• C. Contraction joints are decorative; expansion joints are structural.
• D. Contraction joints are used only in asphalt; expansion joints are used only in concrete.

Answer: (B)

Concrete shrinks as it cures and also expands and contracts with temperature changes. To manage these movements, two kinds of joints are used. Contraction joints, or control joints, are placed to create a planned weak plane so cracks form in a controlled location rather than randomly across the pavement. They don’t stop shrinkage altogether; they guide where cracking will occur to keep the pavement’s appearance and performance better. Expansion joints, on the other hand, provide a full-gap clearance between slabs to let them move apart when temperatures rise and come back together when they cool. This prevents buildup of stress that could cause cracking or buckling. They’re not decorative or structural in themselves—they’re deliberate gaps that accommodate thermal movement between slabs.

Concrete shrinks as it cures and also expands and contracts with temperature changes. To manage these movements, two kinds of joints are used. Contraction joints, or control joints, are placed to create a planned weak plane so cracks form in a controlled location rather than randomly across the pavement. They don’t stop shrinkage altogether; they guide where cracking will occur to keep the pavement’s appearance and performance better.

Expansion joints, on the other hand, provide a full-gap clearance between slabs to let them move apart when temperatures rise and come back together when they cool. This prevents buildup of stress that could cause cracking or buckling. They’re not decorative or structural in themselves—they’re deliberate gaps that accommodate thermal movement between slabs.