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

ASTM C31 requires three equal layers when making 6×12 inch cylindrical specimens consolidated by rodding.

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

ASTM C31 specifies a tamping rod that is 5/8 inch (16 mm) in diameter and at least 24 inches (600 mm) long with a hemispherical tip.

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

Per ASTM C31, the vibrator diameter shall not exceed one-fourth (1/4) of the diameter of the mold being filled.

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

ASTM C31 requires specimens to be maintained between 60°F and 80°F (16°C and 27°C) during the initial curing period.

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

The struck-off top surface must be finished level within 1/16 inch (1.6 mm) of a true plane per ASTM C31.

ACI (American Concrete Institute Certification) Practice Test

ACI (American Concrete Institute Certification) Practice Test

ACI Certification Strength Testing Technician 2