ACI Fresh Concrete Field Testing Questions and Answers

Question 1

An ACI Certified Field Testing Technician is performing a slump test (ASTM C143) on a sample of fresh concrete.
The concrete slumps and falls away to one side.
What is the correct action for the technician to take?

Accepted Answer

Disregard the test and immediately perform a retest on another portion of the same sample.

Answer

Record the slump at the lowest point of the sheared surface.

Answer

Average the highest and lowest points and record that value.

Answer

Reject the entire batch of concrete as it is not cohesive.

Question 2

According to ASTM C172, Standard Practice for Sampling Freshly Mixed Concrete, what is the maximum allowable elapsed time between obtaining the first and final portions of a composite sample?

Accepted Answer

15 minutes

Answer

5 minutes

Answer

10 minutes

Answer

20 minutes

Question 3

A technician is measuring the density (unit weight) of freshly mixed concrete following ASTM C138. After filling the measure and striking off the excess concrete, what is the immediate next step?

Accepted Answer

Clean all excess concrete from the exterior of the measure.

Answer

Weigh the measure with the concrete and subtract the weight of the measure.

Answer

Take the temperature of the concrete in the measure.

Answer

Cover the measure with a glass plate to check for voids.

Question 4

When measuring the temperature of freshly mixed hydraulic-cement concrete (ASTM C1064), how much concrete cover should surround the sensing portion of the temperature measuring device?

Accepted Answer

At least 3 inches (75 mm) in all directions.

Answer

At least 1 inch (25 mm) in all directions.

Answer

At least 2 inches (50 mm) in all directions.

Answer

The device only needs to be submerged halfway.

Question 5

Which of the following is the correct tamping procedure for filling a 0.5 ft³ unit weight measure when performing the test for Density (Unit Weight) of Concrete (ASTM C138)?

Accepted Answer

Fill in 3 equal layers, rodding each layer 50 times.

Answer

Fill in 2 equal layers, rodding each layer 25 times.

Answer

Fill in 3 equal layers, rodding each layer 25 times.

Answer

Fill in 2 equal layers, rodding each layer 50 times.

Question 6

A field test for air content is being performed on lightweight concrete using the volumetric method (ASTM C173). Why is this method specified for lightweight concrete instead of the pressure method (ASTM C231)?

Accepted Answer

The aggregate in lightweight concrete is porous and contains its own air, which would be measured incorrectly by the pressure method.

Answer

The pressure method takes too long for lightweight concrete.

Answer

The aggregate in lightweight concrete can absorb a significant amount of water, affecting the results.

Answer

The volumetric method requires a smaller, more manageable sample size.

An ACI Certified Field Testing Technician is performing a slump test (ASTM C143) on a sample of fresh concrete.The concrete slumps and falls away to one side.What is the correct action for the technician to take?

An ACI Certified Field Testing Technician is performing a slump test (ASTM C143) on a sample of fresh concrete.
The concrete slumps and falls away to one side.
What is the correct action for the technician to take?