Florida DOT Concrete Batchman/Operator Practice Exam

In the adjustment formula, what does SSD aggregate weight per CYD represent?

1. Standard weight of dry aggregate

2. Weight of saturated surface dry aggregate

3. Weight of aggregate in water

4. Standard weight of wet aggregate

The correct answer is: Weight of saturated surface dry aggregate

The weight of saturated surface dry aggregate is a critical aspect in calculating the correct proportions of materials in concrete mix design. In this context, "saturated surface dry" refers to the condition of the aggregate when it contains moisture on its surface but has not absorbed any water. This condition is important because it ensures that the aggregate does not contribute additional water to the mix, allowing for accurate control over the water-to-cement ratio. Using the SSD weight allows concrete batch operators to achieve the desired consistency and strength of the concrete by ensuring that the correct amount of aggregate is used. If the aggregate's weight were referenced in a different condition (such as completely dry or fully saturated), it could lead to inaccurate calculations, which could compromise the quality of the concrete mix. Proper understanding and use of SSD aggregate weight help in maintaining the balance of the mix, leading to improved durability and performance characteristics in the finished concrete.