Florida DOT Concrete Batchman/Operator Practice Exam

Which type of admixture is required to be present in concrete concerning water-reducing properties?

1. Retarding

2. Water-reducing (Type A)

3. Accelerating

4. Expanded

The correct answer is: Water-reducing (Type A)

Water-reducing admixtures, specifically Type A, are essential in concrete mixtures for their ability to enhance workability while reducing the amount of water required in the mix. This property is particularly beneficial because it allows for a higher strength and durability in concrete without compromising the workability. By decreasing the water-cement ratio, these admixtures enable the concrete to maintain good consistency and flow even with lower amounts of water, leading to improved overall performance. In contrast, retarding admixtures are designed to delay the setting time of the concrete, which doesn’t primarily focus on reducing water content but rather on extending the time available for working with the mix. Accelerating admixtures help to speed up the curing process but may not necessarily have an effect on water reduction. Expanded admixtures are used to create lightweight concrete and do not relate to water-reducing properties. Thus, the requirement for an admixture that specifically targets the enhancement of water-reducing properties in concrete is fulfilled by the water-reducing admixture of Type A.