ACI Concrete Field Testing Technician - Grade I Practice Exam 2026 - Free Concrete Field Testing Practice Questions and Study Guide

The correct answer identifies the types of mixers relevant to the sampling method described. Sampling from mixers is crucial to ensure the quality and consistency of concrete. Stationary mixers and paving mixers are two common types, while the identification of revolving drum mixers and open top mixers completes the list of mixers that can be considered for sampling.

Revolving drum mixers are widely used in the industry because they continuously mix concrete in a rotating drum, ensuring a uniform mixture. Open top mixers, on the other hand, are designed for specific applications where the mixture needs to be visible and easily accessible, allowing for straightforward adjustments. Including these two types emphasizes the importance of understanding the variety of mixers used in concrete production and their respective roles in achieving concrete quality.

Other combinations might include mixers that do not pertain to the context of conventional sampling or may refer to specific operational types that do not align with the broader category recognized in industry standards. Hence, understanding the correct types of mixers allows technicians to apply appropriate sampling methods effectively.