Florida DOT Concrete Batchman/Operator Practice Exam

What percentage of concrete composition typically consists of fine and coarse aggregate?

1. 50% to 60%

2. 65% to 75%

3. 75% to 85%

4. 85% to 95%

The correct answer is: 75% to 85%

In concrete composition, fine and coarse aggregates play a crucial role as they are the bulk materials that provide the majority of the volume and stability to the mix. Typically, fine aggregates (like sand) and coarse aggregates (such as gravel or crushed stone) together make up a significant portion of the total concrete volume. The correct percentage range, which is 75% to 85%, reflects the standard practice in concrete mix design where these aggregates contribute not only to the structure's strength but also affect workability, durability, and overall performance of the concrete. Understanding this composition is essential for ensuring the right balance of materials for different concrete applications, whether it be structural uses, pavements, or other construction demands. In contrast, lower percentages would imply a higher content of cement or water, which might not provide the best performance characteristics in most concrete applications, while excessively high percentages could lead to problems with the mix's workability and overall integrity. Therefore, knowing that aggregates typically comprise 75% to 85% of concrete composition is fundamental for a concrete batchman/operator, as it guides the mix design to achieve desired strength and durability.