Which method could be used to enhance the workability of concrete?

Incorporation of chemical admixtures significantly enhances the workability of concrete. These admixtures are specially formulated materials added to the concrete mix to improve its performance and handling characteristics. Specifically, water-reducing admixtures, superplasticizers, and other types of admixtures can increase fluidity without adding extra water, allowing the concrete to be placed and finished more easily. This results in a smoother finish and can enhance the overall quality of the concrete.

While other choices might affect the workability indirectly, they do not specifically target the enhancement of concrete's workability in the same effective manner as chemical admixtures do. Reducing water content generally makes concrete stiffer, fiber reinforcement can alter the mix's texture, and limiting aggregate size may affect other properties more than workability. The tailored approach of using chemical admixtures to modify workability is both well-researched and widely practiced in the industry.