ACI Certification Fresh Concrete Field Testing 2

Question 1

When performing a slump test per ASTM C143, the tamping rod should penetrate the preceding layer by approximately how much?

Accepted Answer

Approximately 1 inch (25 mm) into the underlying layer

Answer

6 inches above the top of the concrete layer

Answer

The rod should never penetrate the previous layer

Answer

The rod should be submerged to the full depth of each layer

Question 2

What does a 'shear slump' vs. a 'true slump' indicate when performing ASTM C143?

Accepted Answer

A shear slump occurs when the concrete shears off to one side rather than subsiding evenly; it indicates an unrepresentative sample or harsh mix, and the test must be repeated

Answer

A shear slump occurs only in high-slump concrete above 8 inches and is always acceptable

Answer

A shear slump indicates high air content and must be reported as zero

Answer

A shear slump is caused by too much vibration during consolidation of the sample

Question 3

At what precision must concrete temperature be recorded when performing field testing per ASTM C1064?

Accepted Answer

To the nearest 1°F (0.5°C)

Answer

To the nearest 5°F (2.5°C)

Answer

To the nearest 0.1°F (0.05°C)

Answer

To the nearest 10°F (5°C)

Question 4

When making concrete test cylinders per ASTM C31, how long must the molds remain undisturbed in the field after casting?

Accepted Answer

A minimum of 24 hours and a maximum of 48 hours, stored at 60–80°F (16–27°C)

Answer

Exactly 12 hours, then immediately transported to the lab

Answer

72 hours at ambient temperature regardless of conditions

Answer

Until the concrete reaches 1,000 psi, measured by penetration resistance

Question 5

Per ASTM C31, how many blows with a rubber mallet are required to close rod holes on each layer when making a 4×8-inch cylinder?

Accepted Answer

10–15 blows around the outside of the mold after each layer is rodded

Answer

5 blows only after the final layer

Answer

25 blows in the same pattern used for rodding

Answer

No mallet tapping is required for 4×8-inch cylinders

Question 6

What is the required composite sample volume when obtaining fresh concrete for a full set of field tests including two 4×8-inch cylinders per ASTM C172?

Accepted Answer

At least 1.0 ft³ (28 L) to ensure sufficient material for all tests and cylinder fabrication

Answer

0.25 ft³ (7 L), one wheelbarrow scoop is sufficient

Answer

Exactly 0.5 ft³ (14 L) per ASTM C172

Answer

2.0 ft³ (57 L) is the mandatory minimum regardless of tests performed