Florida DOT Concrete Batchman/Operator Practice Exam

When using specialty ingredients, initial mixing revolutions may be modified. Which of the following is NOT considered a specialty ingredient?

1. Silica fume

2. Corrosion inhibitor calcium nitrite

3. Coarse aggregate

4. High range water reducers

The correct answer is: Coarse aggregate

Coarse aggregate is considered a standard component in concrete mixtures rather than a specialty ingredient. Specialty ingredients typically refer to materials that are added to enhance specific properties of the concrete or to achieve particular performance characteristics. These include items like silica fume, which improves durability and strength, corrosion inhibitors like calcium nitrite that protect reinforcement from corrosion, and high-range water reducers that enhance workability without adding excessive water. Coarse aggregate, on the other hand, is a fundamental constituent that provides volume and structure to the concrete, making it a common element in all concrete mixes rather than a specialized addition that would alter standard mixing practices. Understanding this distinction is crucial for concrete batch operators to make appropriate adjustments in mixing revolutions when using specialty ingredients.