If bleeding occurs when adding a new slab and it is joined to an older slab, which surface condition is expected?

• A. The surface will lift away from the form
• B. The surface will cure with a gloss finish
• C. The surface will show no defects
• D. The surface will develop cracks

Answer: (D)

Bleeding brings water to the surface as the concrete begins to cure. When a new slab is poured against an older one, the joint is restrained by the existing slab, so the surface moisture and the weak laitance layer created by bleeding create a plane of weakness at the joint. As the concrete continues to cure and shrink, tensile stresses develop at that restrained joint, and the weakened surface is prone to cracking. This is why cracks are the expected surface condition. The other options don’t fit: bleeding does not cause the surface to lift away from the form, nor does it typically yield a gloss finish, and a surface with no defects ignores the moisture and bond issues introduced at the joint.