ACI Concrete Field Testing
Technician- Grade I Questions
with Complete Solutions
Course
ACI Certification
Question 1
Before obtaining a concrete sample from a mixer or truck, the technician should first:
A. Take the first concrete discharged from the chute
B. Discharge the entire load
C. Allow enough concrete to be discharged to ensure the sample is representative
D. Add water to improve workability
Correct Answer: C
Explanation:
According to ASTM C172, the initial portion of the discharge should not be used because it may
not represent the entire batch. Enough concrete should first be discharged before collecting a
representative sample.
Question 2
When performing the slump test, the slump cone should be filled in:
A. Two equal layers
B. Three equal layers
C. Four equal layers
D. One continuous layer
Correct Answer: B
Explanation:
ASTM C143 requires the slump cone to be filled in three equal layers, with each layer rodded
25 times using the standard tamping rod.
,Question 3
Each layer of concrete placed into the slump cone must be rodded:
A. 10 times
B. 15 times
C. 20 times
D. 25 times
Correct Answer: D
Explanation:
Every layer receives 25 strokes of the 5/8-inch diameter tamping rod to ensure proper
consolidation.
Question 4
After lifting the slump cone, the technician should measure slump by determining the vertical
distance between:
A. The base plate and the top of the cone
B. The original height of the mold and the displaced original center of the top surface
C. The highest point of the concrete and the base
D. The edge of the mold and the concrete surface
Correct Answer: B
Explanation:
The slump is measured as the vertical difference between the original height of the mold and the
displaced center of the top surface of the concrete.
Question 5
The slump cone should be lifted:
A. With a twisting motion
B. Slowly and vertically upward without twisting
C. As quickly as possible
, D. Sideways to prevent sticking
Correct Answer: B
Explanation:
ASTM C143 requires the mold to be lifted straight upward in 5 ± 2 seconds without twisting or
lateral movement.
Question 6
Which ASTM standard covers the air content determination using the pressure method?
A. ASTM C31
B. ASTM C172
C. ASTM C231
D. ASTM C138
Correct Answer: C
Explanation:
ASTM C231 describes the pressure method for determining air content in freshly mixed concrete
containing relatively dense aggregate.
Question 7
The standard tamping rod used for the slump test has a diameter of:
A. 1/2 inch (13 mm)
B. 5/8 inch (16 mm)
C. 3/4 inch (19 mm)
D. 1 inch (25 mm)
Correct Answer: B
Explanation:
The standard tamping rod is 5/8 inch (16 mm) in diameter and approximately 24 inches (600
mm) long with a hemispherical tip.
Technician- Grade I Questions
with Complete Solutions
Course
ACI Certification
Question 1
Before obtaining a concrete sample from a mixer or truck, the technician should first:
A. Take the first concrete discharged from the chute
B. Discharge the entire load
C. Allow enough concrete to be discharged to ensure the sample is representative
D. Add water to improve workability
Correct Answer: C
Explanation:
According to ASTM C172, the initial portion of the discharge should not be used because it may
not represent the entire batch. Enough concrete should first be discharged before collecting a
representative sample.
Question 2
When performing the slump test, the slump cone should be filled in:
A. Two equal layers
B. Three equal layers
C. Four equal layers
D. One continuous layer
Correct Answer: B
Explanation:
ASTM C143 requires the slump cone to be filled in three equal layers, with each layer rodded
25 times using the standard tamping rod.
,Question 3
Each layer of concrete placed into the slump cone must be rodded:
A. 10 times
B. 15 times
C. 20 times
D. 25 times
Correct Answer: D
Explanation:
Every layer receives 25 strokes of the 5/8-inch diameter tamping rod to ensure proper
consolidation.
Question 4
After lifting the slump cone, the technician should measure slump by determining the vertical
distance between:
A. The base plate and the top of the cone
B. The original height of the mold and the displaced original center of the top surface
C. The highest point of the concrete and the base
D. The edge of the mold and the concrete surface
Correct Answer: B
Explanation:
The slump is measured as the vertical difference between the original height of the mold and the
displaced center of the top surface of the concrete.
Question 5
The slump cone should be lifted:
A. With a twisting motion
B. Slowly and vertically upward without twisting
C. As quickly as possible
, D. Sideways to prevent sticking
Correct Answer: B
Explanation:
ASTM C143 requires the mold to be lifted straight upward in 5 ± 2 seconds without twisting or
lateral movement.
Question 6
Which ASTM standard covers the air content determination using the pressure method?
A. ASTM C31
B. ASTM C172
C. ASTM C231
D. ASTM C138
Correct Answer: C
Explanation:
ASTM C231 describes the pressure method for determining air content in freshly mixed concrete
containing relatively dense aggregate.
Question 7
The standard tamping rod used for the slump test has a diameter of:
A. 1/2 inch (13 mm)
B. 5/8 inch (16 mm)
C. 3/4 inch (19 mm)
D. 1 inch (25 mm)
Correct Answer: B
Explanation:
The standard tamping rod is 5/8 inch (16 mm) in diameter and approximately 24 inches (600
mm) long with a hemispherical tip.
