Which of the following is a key benefit of troweling concrete surfaces?

Troweling concrete surfaces is a crucial step in flatwork finishing as it compacts the surface and enhances smoothness. When a trowel is applied to the surface of freshly placed concrete, it helps to eliminate imperfections, fills in any voids, and provides a denser surface layer. This not only improves the appearance of the finished product, making it more aesthetically pleasing, but also contributes to strength and durability. A smoother surface results from the compaction process, which is essential for certain applications where a fine finish is required, such as in walkways, driveways, and slabs.

The other choices do not represent the primary purpose of troweling. Increasing air pockets would compromise the strength and durability of the concrete. Adding a color pigment is a separate process and not an outcome of troweling. Reducing the setting time is also unrelated to troweling, as this is influenced by the mix design and environmental conditions rather than the finishing techniques applied.