When attaching a freshly poured slab to a previously constructed one and bleed occurs, what is the expected surface behavior?

• A. The surface will crack along joints
• B. The surface will show increased permeability
• C. The surface will develop cracks
• D. The surface will remain perfectly uniform

Answer: (C)

The surface will crack.

When you place fresh concrete against an already set slab, the new pour is restrained by the old one. Bleeding brings water to the surface during early curing, which can create a laitance layer and slows the early strength gain at the top. As curing proceeds, the surface dries and shrinks, while the underlying material remains restrained by the older slab. That restrained plastic shrinkage produces tensile stresses at the surface, which manifest as cracks, often near the joint where the two pours meet. This cracking is the expected surface behavior, rather than remaining perfectly uniform or becoming more permeable. Proper curing and joint detailing help minimize it.