Florida DOT Concrete Batchman/Operator Practice Exam

What is the moisture condition of the aggregates on the approved concrete mix designs?

1. Oven dry

2. Air dry

3. Surface saturated dry (SSD)

4. Completely saturated

The correct answer is: Surface saturated dry (SSD)

The moisture condition of the aggregates on the approved concrete mix designs is typically considered to be Surface Saturated Dry (SSD). This is important because the SSD condition indicates that the aggregates have absorbed moisture to their saturation point but do not have free water on their surface. This condition allows for accurate calculations of the water-to-cement ratio while ensuring that the concrete mix achieves optimal workability and strength. Using aggregates in the SSD condition ensures that the moisture content is balanced—meaning that any additional water added to the mix will contribute to the hydration process rather than being absorbed by the porous aggregates. This contributes to achieving the desired consistency and performance of the concrete, which is crucial for meeting project specifications. In contrast, other moisture conditions such as oven dry, air dry, or completely saturated would either absorb more water than necessary or contribute excess water to the mixture, potentially leading to issues with the final strength and durability of the concrete. This highlights the significance of using the SSD condition in concrete mix design.