ACI Concrete Field Testing Technician - Grade I Practice Exam

What is the maximum size of aggregate allowed in the concrete test method?

1. 1 inch (25 mm)

2. 1 1/4 inch (31.5 mm)

3. 1 1/2 inch (37.5 mm)

4. 2 inch (50 mm)

The correct answer is: 1 1/2 inch (37.5 mm)

The maximum size of aggregate allowed in concrete test methods is crucial as it directly affects the concrete's workability, strength, and durability. In the context of concrete testing, particularly when referring to field testing methods like those outlined in ASTM standards, a maximum aggregate size of 1 1/2 inches (37.5 mm) is often specified. This size helps ensure that proper mixing and placement techniques can be employed, allowing the cement paste to cover the surfaces of the aggregates adequately and minimizing the risk of segregation during handling. Choosing a maximum size that is too large can lead to difficulties in mixing and could adversely impact the uniformity and performance of the concrete. Moreover, aggregates that exceed this maximum size might not meet performance criteria during various tests. Thus, adherence to a maximum size of 1 1/2 inches balances the need for structural strength and the practicalities of mixing and workability in concrete applications.