ACI Certification Strength Testing Technician 2

Question 1

When consolidating a 6×12 inch concrete cylinder by rodding per ASTM C31, how many equal layers are required?

Accepted Answer

Three layers

Answer

Two layers

Answer

Four layers

Answer

Six layers

Question 2

What are the diameter and minimum length specified for the tamping rod used to consolidate standard concrete cylinder specimens per ASTM C31?

Accepted Answer

5/8-inch diameter, 24 inches long

Answer

3/8-inch diameter, 18 inches long

Answer

3/4-inch diameter, 24 inches long

Answer

1-inch diameter, 30 inches long

Question 3

When using an internal vibrator to consolidate concrete cylinder specimens per ASTM C31, the vibrator diameter must not exceed what fraction of the mold diameter?

Accepted Answer

One-fourth

Answer

One-sixth

Answer

One-third

Answer

One-half

Question 4

Per ASTM C31, what temperature range must be maintained during initial curing of concrete cylinder specimens in the field?

Accepted Answer

60–80°F (16–27°C)

Answer

50–70°F (10–21°C)

Answer

65–90°F (18–32°C)

Answer

70–95°F (21–35°C)

Question 5

After the top surface of a freshly cast cylinder is struck off, it must be finished so that it departs from a true plane by no more than:

Accepted Answer

1/16 inch (1.6 mm)

Answer

1/32 inch (0.8 mm)

Answer

1/8 inch (3 mm)

Answer

3/16 inch (5 mm)

Question 6

Per ASTM C31, freshly cast concrete specimens must be protected from vibration, shock, and disturbance for a minimum of how long after molding?

Accepted Answer

24 hours

Answer

4 hours

Answer

8 hours

Answer

16 hours

Question 7

When making concrete beam specimens for flexural strength testing per ASTM C31, which consolidation method is permitted when the measured slump is 3 inches (75 mm) or greater?

Accepted Answer

Either rodding or internal vibration

Answer

Rodding only

Answer

Internal vibration only

Answer

External vibration only