What is the correct procedure for screeding and strike-off to achieve a level finish?

• A. Use a trowel only and scrape aggressively.
• B. Rely on vibration to level the surface.
• C. Use a straightedge, move uniformly, avoid gouging or dragging; strike-off to final grade, ensure no wedging.
• D. Compress the surface with a heavy plate repeatedly.

Answer: (C)

The essential idea is to establish a true, level surface by controlled screeding and strike-off, using a straightedge to plane the concrete to the final grade without creating gouges or high spots. The straightedge should be placed on the surface and moved in a uniform, steady motion so excess material is cut off evenly across the entire area. Strike-off to the final grade means bringing the surface to the exact planned elevation and plane before finishing operations, leaving a uniform top surface ready for subsequent finishing.

Avoid gouging or dragging the straightedge. Gouging creates indentations and unevenness, while dragging can smear or pull material, forming ridges or low spots. Do not wedge the straightedge into the concrete; forcing it can create high points and disrupt the surface plane. By keeping a light, consistent contact and moving methodically, you achieve a smooth, level finish that is true to grade.

Other methods—relying on vibration to level, using a trowel alone for initial leveling, or repeatedly compressing with a heavy plate—do not establish the correct surface plane during screeding and can disturb the mix, cause segregation, or introduce surface flaws.