Florida DOT Concrete Batchman/Operator Practice Exam

What is the Adjusted Batch Water calculation based on?

1. (batch water) + (aggregate free moisture water weight)

2. (batch water) - (aggregate free moisture water weight)

3. (SSD aggregate weight) + (batch water)

4. (SSD aggregate weight) - (free moisture weight)

The correct answer is: (batch water) - (aggregate free moisture water weight)

The Adjusted Batch Water calculation is critical in ensuring the proper water content in concrete mixes, taking into account the moisture present in the aggregates. This calculation is performed to adjust the amount of water needed for the mix based on the moisture contributed by the aggregates. The correct approach involves subtracting the weight of the free moisture in the aggregates from the total batch water. This is because the free moisture already present in the aggregates contributes to the overall water content in the concrete mix. By removing this weight from the batch water calculation, the result reflects the actual amount of additional water required to achieve the desired water-to-cement ratio. In this context, while the aggregate's free moisture weight must be accounted for, the other choices do not align with the correct protocol for calculating adjusted batch water. Option A adds free moisture instead of subtracting it, which would lead to excess water in the mix. Options C and D focus on adjusting with SSD (Saturated Surface Dry) aggregate weight rather than appropriately addressing the batch water in relation to free moisture. Thus, subtracting the aggregate's free moisture weight from the batch water ensures the correct water content for optimal concrete quality.