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

ASTM C143 requires that the tamping rod penetrate approximately 1 inch (25 mm) into the underlying layer during filling to knit the layers together without excessively disturbing the lower portion.

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

In a shear slump, the upper portion slides off to one side instead of slumping uniformly; ASTM C143 requires that the test be repeated on a fresh sample because the result is not representative.

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

ASTM C1064 requires that concrete temperature be reported to the nearest 1°F (0.5°C), using a thermometer with a resolution of at least 1°F and calibrated to ±1°F accuracy.

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

ASTM C31 requires cylinders to remain in their molds in the field for a minimum of 24 hours and a maximum of 48 hours, protected from vibration and temperature extremes (60–80°F), before transport to the lab.

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

ASTM C31 requires 10–15 blows with a rubber mallet around the outside circumference of the mold after each layer is rodded, to close rod holes and eliminate surface voids regardless of cylinder size.

ACI (American Concrete Institute Certification) Practice Test

ACI (American Concrete Institute Certification) Practice Test

ACI Certification Fresh Concrete Field Testing 2