Which deck type offers acceptable skid resistance but has the drawback of excessive differential shrinkage?

• A. Precast Concrete Deck
• B. Timber Deck
• C. Cast-in-Place (CIP) Concrete Deck
• D. Corrugated Steel Deck

Answer: (C)

Cast-in-place concrete decks can achieve acceptable skid resistance because the surface texture can be finished to provide good friction, using broom finishes, exposed aggregate, or other texturing methods to meet friction specifications.

The drawback comes from the way in-situ concrete dries and contracts. When a large slab is poured and cured on site, it experiences drying shrinkage and temperature gradients. The top surface loses moisture and cools faster than the interior, and the slab is restrained at supports, causing differential movements across the deck. This differential shrinkage can lead to curling, cracking, and other distortion, which is a notable issue for cast-in-place decks.

Precast decks are cured off-site under controlled conditions and joined with joints that accommodate movement, reducing differential shrinkage. Timber decks can shrink or swell with moisture changes and may not consistently meet skid-resistance requirements, while corrugated steel decks rely on surface toppings for friction and have different behavior and maintenance considerations.