Which tool may be used to strike off the top surface of concrete after consolidation?

The strike-off bar is specifically designed for leveling and finishing the surface of freshly placed concrete after it has been properly consolidated. This tool allows the user to effectively remove excess concrete and create a flat, even surface, which is essential for achieving the desired finish and thickness of the concrete slab. The straight edge of the strike-off bar ensures consistency in elevation across the surface, making it crucial for ensuring that the concrete meets the required specifications.

While a rubber mallet, trowel, and measuring cup are useful tools in concrete work, they serve different purposes. A rubber mallet is typically used to help settle forms or to tap on sides to release air bubbles rather than to strike off the surface. A trowel is primarily utilized for smoothing and finishing the surface but is not the main tool for achieving the strike-off process after consolidation. A measuring cup's role is unrelated to finishing concrete surfaces; rather, it's used for measuring smaller quantities of materials.

In summary, the strike-off bar is the most appropriate tool for striking off the top surface of concrete, making it the best answer for this question.