ACI Making and Curing Specimens Questions and Answers

Question 1

According to ASTM C31/C31M, what is the required temperature range for the initial curing of standard-cured concrete cylinders with a specified strength of less than 6000 psi (40 MPa)?

Accepted Answer

60°F to 80°F (16°C to 27°C)

Answer

50°F to 70°F (10°C to 21°C)

Answer

68°F to 78°F (20°C to 26°C)

Answer

70°F to 90°F (21°C to 32°C)

Question 2

A technician is preparing to cast 6x12-inch concrete cylinders. The concrete has a slump of 3 inches. Which of the following consolidation procedures is correct?

Accepted Answer

Fill the mold in three equal layers, rodding each layer 25 times.

Answer

Fill the mold in two equal layers, rodding each layer 25 times.

Answer

Fill the mold in three equal layers, rodding each layer 50 times.

Answer

Fill the mold in two equal layers, vibrating for 5 seconds per layer.

Question 3

Which of the following is an appropriate action immediately after molding and finishing a concrete test specimen?

Accepted Answer

Place the specimen in its initial curing location, protected from moisture loss and disturbance.

Answer

Leave the specimen uncovered to allow bleed water to evaporate quickly.

Answer

Move the specimen to the final curing location in the laboratory.

Answer

Submerge the specimen in ice water to rapidly cool it to the required curing temperature.

Question 4

A field-cured specimen is primarily used to determine:

Accepted Answer

The in-place strength of the concrete in the structure.

Answer

The adequacy of the concrete mixture proportions for strength.

Answer

Acceptance of the concrete for specified strength.

Answer

The quality control of the concrete producer.

Question 5

When rodding the top layer of a concrete cylinder, the tamping rod should penetrate the underlying layer by approximately how much?

Accepted Answer

1 inch (25 mm)

Answer

The rod should not penetrate the underlying layer.

Answer

1/2 inch (13 mm)

Answer

2 inches (50 mm)

Question 6

During the initial curing period, standard-cured specimens must be transported to the laboratory for final curing. This transport must occur within what timeframe after molding?

Accepted Answer

Within 48 hours

Answer

Within 12 hours

Answer

Within 24 hours

Answer

Within 72 hours