LATEST CONCRETE CONSTRUCTION
MATERIALS TESTING CERTIFICATION EXAM
OFFERED BY NICET | Q&A WITH RATIONALES
1. Which ASTM standard covers the sampling of
freshly mixed concrete?
A) ASTM C39
B) ASTM C172
C) ASTM C143
D) ASTM C31
Correct answer: B
Rationale: ASTM C172 is the standard practice for
sampling freshly mixed concrete, ensuring that
representative samples are collected for
subsequent testing. ASTM C31 covers making and
curing test specimens, C143 covers slump, and C39
covers compressive strength.
2. According to ASTM C172, what is the minimum
number of increments required to form a composite
sample from a ready‑mix truck?
A) 1 increment
,B) 2 increments
C) 3 increments
D) 4 increments
Correct answer: B
Rationale: ASTM C172 requires obtaining two
regularly spaced increments from the middle of the
discharge to form a composite sample that
represents the entire load.
3. A technician is performing a slump test (ASTM
C143). The concrete slumps unevenly, with the
center higher than the edges. What does this
indicate?
A) Normal behavior
B) The concrete is too wet
C) Segregation or a poorly graded mixture
D) The mold was not properly wetted
Correct answer: C
Rationale: An uneven slump (center higher than
edges) often indicates that the concrete lacks
cohesion, leading to segregation. This can affect
strength and durability.
,4. In ASTM C143, what is the standard procedure for
filling the slump cone?
A) Fill in one layer, rod 25 times
B) Fill in three equal layers, rod each layer 25 times
C) Fill in two equal layers, rod each layer 50 times
D) Fill the cone without rodding
Correct answer: B
Rationale: The slump cone is filled in three equal
layers, with each layer rodded 25 times to
consolidate the concrete and remove entrapped air.
5. A concrete cylinder is measured for compressive
strength at 28 days and yields 4,800 psi. The
specified strength (f'c) is 4,000 psi. What is the
strength ratio?
A) 0.83
B) 1.00
C) 1.20
D) 1.33
Correct answer: C
, Rationale: The strength ratio is the measured
strength divided by the specified strength: 4,800 psi
/ 4,000 psi = 1.20. This indicates the concrete
exceeds the specified strength.
6. Which of the following is NOT a required test for
fresh concrete in ASTM C172?
A) Slump
B) Air content
C) Compressive strength
D) Temperature
Correct answer: C
Rationale: Compressive strength is determined on
hardened concrete specimens (cylinders or cubes)
and is not a fresh concrete test. Slump, air content,
and temperature are fresh concrete tests.
7. According to ASTM C31, what is the maximum
time allowed between obtaining the final portion of
the concrete sample and the start of cylinder
molding?
A) 5 minutes
MATERIALS TESTING CERTIFICATION EXAM
OFFERED BY NICET | Q&A WITH RATIONALES
1. Which ASTM standard covers the sampling of
freshly mixed concrete?
A) ASTM C39
B) ASTM C172
C) ASTM C143
D) ASTM C31
Correct answer: B
Rationale: ASTM C172 is the standard practice for
sampling freshly mixed concrete, ensuring that
representative samples are collected for
subsequent testing. ASTM C31 covers making and
curing test specimens, C143 covers slump, and C39
covers compressive strength.
2. According to ASTM C172, what is the minimum
number of increments required to form a composite
sample from a ready‑mix truck?
A) 1 increment
,B) 2 increments
C) 3 increments
D) 4 increments
Correct answer: B
Rationale: ASTM C172 requires obtaining two
regularly spaced increments from the middle of the
discharge to form a composite sample that
represents the entire load.
3. A technician is performing a slump test (ASTM
C143). The concrete slumps unevenly, with the
center higher than the edges. What does this
indicate?
A) Normal behavior
B) The concrete is too wet
C) Segregation or a poorly graded mixture
D) The mold was not properly wetted
Correct answer: C
Rationale: An uneven slump (center higher than
edges) often indicates that the concrete lacks
cohesion, leading to segregation. This can affect
strength and durability.
,4. In ASTM C143, what is the standard procedure for
filling the slump cone?
A) Fill in one layer, rod 25 times
B) Fill in three equal layers, rod each layer 25 times
C) Fill in two equal layers, rod each layer 50 times
D) Fill the cone without rodding
Correct answer: B
Rationale: The slump cone is filled in three equal
layers, with each layer rodded 25 times to
consolidate the concrete and remove entrapped air.
5. A concrete cylinder is measured for compressive
strength at 28 days and yields 4,800 psi. The
specified strength (f'c) is 4,000 psi. What is the
strength ratio?
A) 0.83
B) 1.00
C) 1.20
D) 1.33
Correct answer: C
, Rationale: The strength ratio is the measured
strength divided by the specified strength: 4,800 psi
/ 4,000 psi = 1.20. This indicates the concrete
exceeds the specified strength.
6. Which of the following is NOT a required test for
fresh concrete in ASTM C172?
A) Slump
B) Air content
C) Compressive strength
D) Temperature
Correct answer: C
Rationale: Compressive strength is determined on
hardened concrete specimens (cylinders or cubes)
and is not a fresh concrete test. Slump, air content,
and temperature are fresh concrete tests.
7. According to ASTM C31, what is the maximum
time allowed between obtaining the final portion of
the concrete sample and the start of cylinder
molding?
A) 5 minutes
