LATEST CONSTRUCTION MATERIALS TESTING
(CMT) LEVEL I–IV CERTIFICATION EXAM
OFFERED BY NICET | Q&A WITH RATIONALES
1. What is the standard slump range for a typical
residential footing concrete mix (low slump)?
A) 1–2 inches (25–50 mm)
B) 3–4 inches (75–100 mm)
C) 5–6 inches (125–150 mm)
D) 7–8 inches (175–200 mm)
Correct answer: B
Rationale: Slump for footings is typically 3–4 inches
(75–100 mm) to provide workability without
excessive water. Higher slumps can increase the
risk of segregation and reduce strength.
2. Which ASTM standard covers the slump test for
hydraulic cement concrete?
A) ASTM C143
B) ASTM C172
C) ASTM C31
,D) ASTM C39
Correct answer: A
Rationale: ASTM C143 is the standard test method
for slump of hydraulic-cement concrete. ASTM C172
covers sampling, C31 covers specimen fabrication,
and C39 covers compressive strength testing.
3. According to ASTM C172, what is the minimum
sample size for concrete with a nominal maximum
aggregate size of 1 inch (25 mm)?
A) 0.5 ft³ (14 L)
B) 1.0 ft³ (28 L)
C) 1.5 ft³ (42 L)
D) 2.0 ft³ (56 L)
Correct answer: B
Rationale: For aggregate up to 1 inch, the minimum
sample volume is 1.0 ft³ (28 L) to ensure a
representative composite. Larger aggregates
require larger sample volumes.
4. A technician is performing a standard Proctor
compaction test (ASTM D698) and notices the soil
,begins to displace laterally under the rammer blows,
"sponging" without increasing density. What is the
most appropriate adjustment?
A) Increase compaction effort by switching to the
modified Proctor method
B) Dry the soil back to a lower moisture content
before re‑compacting
C) Add water in 4% increments to liquefy the soil
D) Record the wet density as maximum dry density
and terminate the test
Correct answer: B
Rationale: The "sponging" effect occurs when soil
moisture exceeds optimum, causing pore water
pressure to resist compaction. Drying back to a
lower moisture content is required to properly
define the moisture-density curve.
5. When performing an in‑place density test using a
nuclear density gauge (ASTM D6938) via the direct
transmission method, the technician encounters a
large stone exactly along the path of the probe drive
pin. What action must be taken?
, A) Drive the pin through the rock using a heavier
sledgehammer
B) Pull the pin out halfway and run the test in
backscatter mode
C) Abandon the hole and move the gauge to a new
adjacent location
D) Remove the stone, backfill with loose soil, and
drive the pin into the backfill
Correct answer: C
Rationale: Striking a large stone can damage the
equipment or create a void that skews nuclear
readings. Moving to an adjacent representative
location ensures data integrity without altering the
compaction state.
6. In a Superpave gyratory compactor, what is the
primary purpose of the device?
A) To simulate traffic loading and densification
B) To perform Marshall impact compaction
C) To control field rolling temperature
D) To test aggregate crushing resistance
Correct answer: A
(CMT) LEVEL I–IV CERTIFICATION EXAM
OFFERED BY NICET | Q&A WITH RATIONALES
1. What is the standard slump range for a typical
residential footing concrete mix (low slump)?
A) 1–2 inches (25–50 mm)
B) 3–4 inches (75–100 mm)
C) 5–6 inches (125–150 mm)
D) 7–8 inches (175–200 mm)
Correct answer: B
Rationale: Slump for footings is typically 3–4 inches
(75–100 mm) to provide workability without
excessive water. Higher slumps can increase the
risk of segregation and reduce strength.
2. Which ASTM standard covers the slump test for
hydraulic cement concrete?
A) ASTM C143
B) ASTM C172
C) ASTM C31
,D) ASTM C39
Correct answer: A
Rationale: ASTM C143 is the standard test method
for slump of hydraulic-cement concrete. ASTM C172
covers sampling, C31 covers specimen fabrication,
and C39 covers compressive strength testing.
3. According to ASTM C172, what is the minimum
sample size for concrete with a nominal maximum
aggregate size of 1 inch (25 mm)?
A) 0.5 ft³ (14 L)
B) 1.0 ft³ (28 L)
C) 1.5 ft³ (42 L)
D) 2.0 ft³ (56 L)
Correct answer: B
Rationale: For aggregate up to 1 inch, the minimum
sample volume is 1.0 ft³ (28 L) to ensure a
representative composite. Larger aggregates
require larger sample volumes.
4. A technician is performing a standard Proctor
compaction test (ASTM D698) and notices the soil
,begins to displace laterally under the rammer blows,
"sponging" without increasing density. What is the
most appropriate adjustment?
A) Increase compaction effort by switching to the
modified Proctor method
B) Dry the soil back to a lower moisture content
before re‑compacting
C) Add water in 4% increments to liquefy the soil
D) Record the wet density as maximum dry density
and terminate the test
Correct answer: B
Rationale: The "sponging" effect occurs when soil
moisture exceeds optimum, causing pore water
pressure to resist compaction. Drying back to a
lower moisture content is required to properly
define the moisture-density curve.
5. When performing an in‑place density test using a
nuclear density gauge (ASTM D6938) via the direct
transmission method, the technician encounters a
large stone exactly along the path of the probe drive
pin. What action must be taken?
, A) Drive the pin through the rock using a heavier
sledgehammer
B) Pull the pin out halfway and run the test in
backscatter mode
C) Abandon the hole and move the gauge to a new
adjacent location
D) Remove the stone, backfill with loose soil, and
drive the pin into the backfill
Correct answer: C
Rationale: Striking a large stone can damage the
equipment or create a void that skews nuclear
readings. Moving to an adjacent representative
location ensures data integrity without altering the
compaction state.
6. In a Superpave gyratory compactor, what is the
primary purpose of the device?
A) To simulate traffic loading and densification
B) To perform Marshall impact compaction
C) To control field rolling temperature
D) To test aggregate crushing resistance
Correct answer: A
