What does fine aggregate improve when mixed with coarse aggregate?

Fine aggregate plays a crucial role in the overall performance of concrete by improving its workability. When mixed with coarse aggregate, fine aggregates fill the voids between the larger particles, creating a denser and more cohesive mixture. This results in better flow characteristics, making it easier to place and compact the concrete.

Enhanced workability is particularly important in construction because it facilitates the movement of the mix and the filling of forms, which can lead to a more uniform finish and reduced labor effort. In addition, more workable mixtures tend to form fewer air pockets, leading to improved strength and durability of the final concrete product.

The other options—structural support, color consistency, and cost efficiency—do not directly reflect the primary function of fine aggregate in a concrete mixture. While they can be influenced by the aggregate composition, the immediate benefit of using fine aggregate is its significant impact on the mixture's workability.