ACI Concrete Field Testing Technician - Grade I Practice Exam

Vibration of a concrete sample is prohibited when the slump exceeds how many millimeters?

50 mm 75 mm 100 mm 125 mm

Correct Answer:

75 mm

Explanation:

The prohibition of vibration for concrete samples with a slump that exceeds 75 millimeters is based on the need to maintain the integrity and true representation of the concrete’s workability. When the slump is greater than this threshold, the concrete mix is considered to be more fluid or workable, which can lead to segregation if it is vibrated. Vibration is used to eliminate air pockets and ensure uniformity in less workable mixtures. However, in high-slump mixes, the additional vibration can cause the heavier aggregates to settle and lead to separation of the components, resulting in a misleading slump test result. Therefore, adhering to this guideline is essential for producing reliable and consistent concrete testing outcomes.

Access more questions from this quiz

Continue to ACI Concrete Field Testing Technician - Grade I Practice Exam for more practice questions and the full quiz experience.

Access More Questions