ACI Concrete Field Testing Technician - Grade I Practice Exam

How is the final slump measured after the test?

1. By measuring the height of the mold

2. By determining the volume of the concrete

3. By comparing initial and final heights in vertical distance

4. By visual inspection only

The correct answer is: By comparing initial and final heights in vertical distance

The final slump is measured by comparing the initial height of the concrete in the mold to the final height after the mold is removed. This method involves placing the concrete in a standardized slump cone, allowing it to settle, and then measuring how much the concrete has slumped or settled. The difference between the original height of the concrete in the cone and the height of the concrete after it has been lifted gives a direct measurement of the slump, which is expressed in inches or millimeters. This provides a precise and quantifiable way to assess the workability of the concrete mix. Other methods, such as measuring the height of the mold, determining the volume of the concrete, or relying solely on visual inspection, do not yield the same level of accuracy and objectivity in measuring concrete slump. These alternatives do not effectively capture the necessary data to evaluate the concrete consistency and flow characteristics accurately.