Florida DOT Concrete Batchman/Operator Practice Exam

Which admixture is commonly associated with enhancing workability in concrete?

1. Calcium Nitrite

2. Superplasticizers

3. Fly Ash

4. Water Reducers

The correct answer is: Superplasticizers

Superplasticizers are a type of chemical admixture specifically designed to enhance the workability of concrete. They function by significantly increasing the fluidity of the mix without adding extra water, which can compromise the strength and durability of the concrete. This makes it easier to mix, place, and finish the concrete, particularly in complex forms or heavily reinforced areas. The effect of superplasticizers is particularly beneficial in high-performance concrete applications where a low water-to-cement ratio is desired. By improving the workability of the mix, superplasticizers allow for the production of concrete that has superior mechanical and durability properties while maintaining a manageable consistency during placement. In contrast, while water reducers also improve workability, they do so typically in a less dramatic fashion compared to superplasticizers and may not achieve the same level of fluidity. Calcium nitrite is primarily used as a corrosion inhibitor in concrete, and fly ash serves as a partial replacement for Portland cement that can enhance certain properties but not specifically workability to the extent that superplasticizers do.