Which reinforcement is used for temperature and shrinkage in a concrete deck?

• A. Primary reinforcement
• B. Secondary reinforcement
• C. Positive Moment Tension
• D. Negative Moment Tension

Answer: (B)

Temperature and shrinkage cracking happen as concrete cures and dries and as it experiences temperature changes. To control these cracks, engineers use distributed reinforcement known as secondary reinforcement. This type isn’t intended to carry the main bending loads; instead it limits crack widths and helps keep the deck durable by spreading stresses from temperature changes and shrinkage. In practice, secondary reinforcement is often a grid of smaller bars or welded wire fabric placed in a layer close to the surface or in both top and bottom layers, depending on the design.

Primary reinforcement, by contrast, is sized and spaced to resist the main flexural stresses from loads, not specifically to control shrinkage cracks. The terms positive and negative moment describe where bending tension occurs in a member, not a type of reinforcement. So, for temperature and shrinkage control in a concrete deck, secondary reinforcement is the appropriate choice.