ACI Concrete Field Testing Technician - Practice Exam
100 Questions with Answers and Rationale
1. According to ASTM C172, how many portions are required to obtain a
composite sample of concrete?
A. One
B. Two
C. Three
D. Four
Answer: C
Rationale: ASTM C172 requires at least two portions, but three or more are typically
taken to ensure the sample is representative of the entire batch. The exam standard
answer is three portions.
2. What is the maximum time allowed to begin slump, air content, and
temperature tests after obtaining the final portion of the sample?
A. 5 minutes
B. 10 minutes
C. 15 minutes
D. 30 minutes
Answer: C
Rationale: ASTM C172 requires that tests begin within 15 minutes after the final
portion is collected to prevent changes in concrete properties.
,3. The slump test (ASTM C143) measures:
A. Strength
B. Air content
C. Workability/consistency
D. Density
Answer: C
Rationale: Slump measures the consistency and workability of fresh concrete, not
strength or air content.
4. The slump cone must be filled in how many equal layers?
A. One
B. Two
C. Three
D. Four
Answer: C
Rationale: ASTM C143 requires the cone to be filled in three equal layers, each rodded
25 times.
5. How many times is each layer rodded during the slump test?
A. 10
B. 15
C. 20
D. 25
Answer: D
Rationale: Each of the three layers must be rodded exactly 25 times with the tamping
rod to properly consolidate the concrete.
6. What is the diameter of the tamping rod used in the slump test?
,A. 1/2 inch
B. 5/8 inch
C. 3/4 inch
D. 1 inch
Answer: B
*Rationale: ASTM standards specify a 5/8-inch diameter, smooth, round steel rod
with a hemispherical tip.*
7. The slump cone must be lifted:
A. Slowly over 1 minute
B. Sideways
C. Vertically in 5 ± 2 seconds
D. Immediately after rodding
Answer: C
Rationale: The cone must be lifted straight up, without twisting, in 5 ± 2 seconds to
ensure accurate results.
8. If the concrete shears or collapses during a slump test, the test is:
A. Recorded
B. Adjusted
C. Discarded and repeated
D. Accepted
Answer: C
Rationale: Shear or collapse slumps are invalid and require the test to be repeated with
a new sample.
9. ASTM C1064 measures:
A. Density
B. Temperature
, C. Air content
D. Yield
Answer: B
Rationale: ASTM C1064 is the standard test method for measuring the temperature of
freshly mixed concrete.
10. The temperature measuring device must be accurate to within:
A. ± 0.1°F
B. ± 0.5°F
C. ± 1.0°F
D. ± 2.0°F
Answer: C
Rationale: ASTM C1064 requires the thermometer to be accurate within ± 1°F (±
0.5°C).
11. How long must the thermometer remain in the concrete before reading?
A. 30 seconds
B. 1 minute
C. 2 minutes
D. Until stabilized (minimum 2 minutes)
Answer: D
Rationale: The thermometer must remain until the reading stabilizes, but at least 2
minutes and not more than 5 minutes.
12. ASTM C231 measures air content using:
A. Volumetric method
B. Gravimetric method
C. Pressure method
D. Displacement method
100 Questions with Answers and Rationale
1. According to ASTM C172, how many portions are required to obtain a
composite sample of concrete?
A. One
B. Two
C. Three
D. Four
Answer: C
Rationale: ASTM C172 requires at least two portions, but three or more are typically
taken to ensure the sample is representative of the entire batch. The exam standard
answer is three portions.
2. What is the maximum time allowed to begin slump, air content, and
temperature tests after obtaining the final portion of the sample?
A. 5 minutes
B. 10 minutes
C. 15 minutes
D. 30 minutes
Answer: C
Rationale: ASTM C172 requires that tests begin within 15 minutes after the final
portion is collected to prevent changes in concrete properties.
,3. The slump test (ASTM C143) measures:
A. Strength
B. Air content
C. Workability/consistency
D. Density
Answer: C
Rationale: Slump measures the consistency and workability of fresh concrete, not
strength or air content.
4. The slump cone must be filled in how many equal layers?
A. One
B. Two
C. Three
D. Four
Answer: C
Rationale: ASTM C143 requires the cone to be filled in three equal layers, each rodded
25 times.
5. How many times is each layer rodded during the slump test?
A. 10
B. 15
C. 20
D. 25
Answer: D
Rationale: Each of the three layers must be rodded exactly 25 times with the tamping
rod to properly consolidate the concrete.
6. What is the diameter of the tamping rod used in the slump test?
,A. 1/2 inch
B. 5/8 inch
C. 3/4 inch
D. 1 inch
Answer: B
*Rationale: ASTM standards specify a 5/8-inch diameter, smooth, round steel rod
with a hemispherical tip.*
7. The slump cone must be lifted:
A. Slowly over 1 minute
B. Sideways
C. Vertically in 5 ± 2 seconds
D. Immediately after rodding
Answer: C
Rationale: The cone must be lifted straight up, without twisting, in 5 ± 2 seconds to
ensure accurate results.
8. If the concrete shears or collapses during a slump test, the test is:
A. Recorded
B. Adjusted
C. Discarded and repeated
D. Accepted
Answer: C
Rationale: Shear or collapse slumps are invalid and require the test to be repeated with
a new sample.
9. ASTM C1064 measures:
A. Density
B. Temperature
, C. Air content
D. Yield
Answer: B
Rationale: ASTM C1064 is the standard test method for measuring the temperature of
freshly mixed concrete.
10. The temperature measuring device must be accurate to within:
A. ± 0.1°F
B. ± 0.5°F
C. ± 1.0°F
D. ± 2.0°F
Answer: C
Rationale: ASTM C1064 requires the thermometer to be accurate within ± 1°F (±
0.5°C).
11. How long must the thermometer remain in the concrete before reading?
A. 30 seconds
B. 1 minute
C. 2 minutes
D. Until stabilized (minimum 2 minutes)
Answer: D
Rationale: The thermometer must remain until the reading stabilizes, but at least 2
minutes and not more than 5 minutes.
12. ASTM C231 measures air content using:
A. Volumetric method
B. Gravimetric method
C. Pressure method
D. Displacement method
