What should you check before finishing a slab to ensure good surface quality?

• A. Subgrade condition, slump, air content, bleed water, surface moisture, temperature, and form alignment
• B. Subgrade condition only
• C. Slump only
• D. Temperature only

Answer: (A)

You must evaluate several interrelated conditions that directly influence how the surface will look and hold up after finishing. The subgrade must be properly compacted, drained, and dry so the slab has solid support and won’t settle or crack later. The forms that define the slab edges should be straight, tight, and correctly aligned to deliver a true, level surface. The concrete’s slump tells you if the mix has the right workability—too stiff or too fluid can lead to roughness, laitance, or surface segregation during finishing. Air content matters for durability and surface texture, so it should be within the specified range to avoid voids or overly dense, hard-to-finish surfaces. Bleed water at the surface needs to be managed because excess bleed can form a weak, powdery layer, while too little can trap laitance and hinder finishing. Surface moisture and temperature also play roles: moisture on the surface and the ambient and concrete temperatures affect evaporation rate, curing, and the ability to achieve a smooth, uniform finish within the finishing window.

All these factors together influence surface quality, so you check them in combination rather than focusing on just one aspect.