ACI CONCRETE FIELD TESTING
TECHNICIAN GRADE I ACTUAL
EXAM 2026/2027 | ASTM Standards |
Comprehensive Practice Test | Verified
Q&A | Pass Guaranteed - A+ Graded
Section 1: ASTM C172 – Sampling Fresh Concrete (30
Questions)
Q1: After sampling is completed, start the tests for slump and air content within:
A. 2½ minutes
B. 5 minutes [CORRECT]
C. 10 minutes
D. 15 minutes
Correct Answer: B
Rationale: ASTM C172 Para (4.1.2) requires that tests for slump, temperature, and air content
be started within 5 minutes after obtaining the final portion of the composite sample. This
ensures the concrete is tested while still fresh and representative of the batch condition.
Waiting longer than 5 minutes allows slump loss and air content changes due to hydration
and environmental exposure.
Q2: Start molding specimens for strength tests within how many minutes after fabricating the
composite sample?
🧠 ANSWER ✔✔ 15 minutes [ASTM C172 Para (4.1.2)]
Q3: The maximum allowable time between obtaining the first and last portions of the
composite sample shall not exceed:
A. 5 minutes
B. 10 minutes
C. 15 minutes [CORRECT]
,D. 20 minutes
Correct Answer: C
Rationale: ASTM C172 Para (4.1) specifies that the elapsed time shall not exceed 15 minutes
between obtaining the first and final portions of the composite sample. This time limit
ensures the composite sample represents a uniform cross-section of the batch without
significant hydration or segregation affecting different portions.
Q4: When sampling from a revolving drum truck mixer, the sample must be obtained:
A. Before any water or admixtures are added
B. After all water and admixtures are added [CORRECT]
C. During the addition of chemical admixtures only
D. At any point during the mixing cycle
Correct Answer: B
Rationale: ASTM C172 Para (4.2.1) requires sampling from revolving drum truck mixers after
all water and admixtures have been added and mixed. This ensures the sample represents the
fully batched concrete with all components properly incorporated. Sampling before complete
mixing yields unrepresentative results.
Q5: When sampling from a stationary mixer, the sample shall not be taken before what
percentage of the batch has been discharged?
A. 5%
B. 10% [CORRECT]
C. 15%
D. 25%
Correct Answer: B
Rationale: ASTM C172 Para (4.2.2) prohibits sampling before 10% of the batch has been
discharged from stationary mixers. The initial discharge often contains segregated materials
or mortar coating the mixer throat. Waiting until 10% discharge ensures representative
concrete flow from the mixer.
Q6: The minimum sample size required for strength test specimens is:
A. 0.5 cubic foot [14 liters]
B. 1 cubic foot [28 liters] [CORRECT]
C. 1.5 cubic feet [42 liters]
D. 2 cubic feet [56 liters]
,Correct Answer: B
Rationale: ASTM C172 Para (4.3) requires a minimum sample size of 1 cubic foot [28 liters]
when molding strength test specimens. This volume ensures adequate concrete for required
specimens (typically 2-6 cylinders) plus extra for slump, air content, and temperature tests
without remixing or adding concrete after initial molding.
Q7: When combining portions to form a composite sample, you must:
A. Pour them together without mixing
B. Remix the entire composite sample [CORRECT]
C. Let them sit for 5 minutes before combining
D. Discard the first portion and use only the last
Correct Answer: B
Rationale: ASTM C172 Para (4.1) requires remixing the entire composite sample after
combining all portions. This ensures uniformity throughout the sample and eliminates
segregation that may have occurred during sampling. The composite sample must be
protected from sun, wind, and contamination during this process.
Q8: If the nominal maximum aggregate size exceeds the appropriate size for molds or testing
equipment, you must:
A. Test the concrete as-is with larger equipment
B. Wet sieve the sample over a 1-inch [25 mm] sieve [CORRECT]
C. Crush the aggregate to smaller size
D. Use a different sampling method
Correct Answer: B
Rationale: ASTM C172 Para (4.4) requires wet sieving over a 1-inch [25 mm] sieve when
aggregate is larger than appropriate for molds or test apparatus. This removes oversize
aggregate while preserving the mortar fraction. Sieving must be done promptly to prevent
moisture loss affecting air content and slump results.
Q9: When sampling from a paving mixer (non-agitating equipment), the composite sample
must consist of at least:
A. One portion from the beginning of discharge
B. Two portions from the middle of discharge only
C. Three portions taken at regularly spaced intervals during discharge [CORRECT]
D. Five portions taken randomly
, Correct Answer: C
Rationale: ASTM C172 Para (4.2.3) requires at least three portions taken at regularly spaced
intervals during discharge from non-agitating equipment. Paving mixers have greater
segregation potential; multiple portions ensure representative sampling across the entire
batch discharge sequence.
Q10: Protection of concrete samples from environmental conditions includes all EXCEPT:
A. Protection from direct sunlight
B. Protection from wind causing rapid evaporation
C. Protection from contamination by foreign materials
D. Protection from carbonation by covering with wet burlap only [CORRECT]
Correct Answer: D
Rationale: ASTM C172 Para (4.1) requires protection from sun, wind, contamination, and rapid
evaporation. While wet burlap provides moisture retention, it does not protect against
carbonation (which requires impermeable covers). The standard emphasizes environmental
protection during the critical 15-minute sampling window, not carbonation prevention during
initial curing.
Q11: The composite sample for a single set of strength specimens must be obtained from:
A. Different batches mixed on the same day
B. A single batch of concrete [CORRECT]
C. Multiple trucks if they arrive within 5 minutes
D. Any concrete with the same mix design
Correct Answer: B
Rationale: ASTM C172 Para (4.1) defines the composite sample as representative of a single
batch. Each batch requires its own composite sample for testing. Combining concrete from
different batches, even with identical mix designs, creates an unrepresentative sample that
invalidates test results and quality control data.
Q12: When sampling from a truck mixer, the discharge must be running at the:
A. Slowest possible speed
B. Normal operating speed [CORRECT]
C. Maximum possible speed
D. Intermittent stop-start pattern
Correct Answer: B
TECHNICIAN GRADE I ACTUAL
EXAM 2026/2027 | ASTM Standards |
Comprehensive Practice Test | Verified
Q&A | Pass Guaranteed - A+ Graded
Section 1: ASTM C172 – Sampling Fresh Concrete (30
Questions)
Q1: After sampling is completed, start the tests for slump and air content within:
A. 2½ minutes
B. 5 minutes [CORRECT]
C. 10 minutes
D. 15 minutes
Correct Answer: B
Rationale: ASTM C172 Para (4.1.2) requires that tests for slump, temperature, and air content
be started within 5 minutes after obtaining the final portion of the composite sample. This
ensures the concrete is tested while still fresh and representative of the batch condition.
Waiting longer than 5 minutes allows slump loss and air content changes due to hydration
and environmental exposure.
Q2: Start molding specimens for strength tests within how many minutes after fabricating the
composite sample?
🧠 ANSWER ✔✔ 15 minutes [ASTM C172 Para (4.1.2)]
Q3: The maximum allowable time between obtaining the first and last portions of the
composite sample shall not exceed:
A. 5 minutes
B. 10 minutes
C. 15 minutes [CORRECT]
,D. 20 minutes
Correct Answer: C
Rationale: ASTM C172 Para (4.1) specifies that the elapsed time shall not exceed 15 minutes
between obtaining the first and final portions of the composite sample. This time limit
ensures the composite sample represents a uniform cross-section of the batch without
significant hydration or segregation affecting different portions.
Q4: When sampling from a revolving drum truck mixer, the sample must be obtained:
A. Before any water or admixtures are added
B. After all water and admixtures are added [CORRECT]
C. During the addition of chemical admixtures only
D. At any point during the mixing cycle
Correct Answer: B
Rationale: ASTM C172 Para (4.2.1) requires sampling from revolving drum truck mixers after
all water and admixtures have been added and mixed. This ensures the sample represents the
fully batched concrete with all components properly incorporated. Sampling before complete
mixing yields unrepresentative results.
Q5: When sampling from a stationary mixer, the sample shall not be taken before what
percentage of the batch has been discharged?
A. 5%
B. 10% [CORRECT]
C. 15%
D. 25%
Correct Answer: B
Rationale: ASTM C172 Para (4.2.2) prohibits sampling before 10% of the batch has been
discharged from stationary mixers. The initial discharge often contains segregated materials
or mortar coating the mixer throat. Waiting until 10% discharge ensures representative
concrete flow from the mixer.
Q6: The minimum sample size required for strength test specimens is:
A. 0.5 cubic foot [14 liters]
B. 1 cubic foot [28 liters] [CORRECT]
C. 1.5 cubic feet [42 liters]
D. 2 cubic feet [56 liters]
,Correct Answer: B
Rationale: ASTM C172 Para (4.3) requires a minimum sample size of 1 cubic foot [28 liters]
when molding strength test specimens. This volume ensures adequate concrete for required
specimens (typically 2-6 cylinders) plus extra for slump, air content, and temperature tests
without remixing or adding concrete after initial molding.
Q7: When combining portions to form a composite sample, you must:
A. Pour them together without mixing
B. Remix the entire composite sample [CORRECT]
C. Let them sit for 5 minutes before combining
D. Discard the first portion and use only the last
Correct Answer: B
Rationale: ASTM C172 Para (4.1) requires remixing the entire composite sample after
combining all portions. This ensures uniformity throughout the sample and eliminates
segregation that may have occurred during sampling. The composite sample must be
protected from sun, wind, and contamination during this process.
Q8: If the nominal maximum aggregate size exceeds the appropriate size for molds or testing
equipment, you must:
A. Test the concrete as-is with larger equipment
B. Wet sieve the sample over a 1-inch [25 mm] sieve [CORRECT]
C. Crush the aggregate to smaller size
D. Use a different sampling method
Correct Answer: B
Rationale: ASTM C172 Para (4.4) requires wet sieving over a 1-inch [25 mm] sieve when
aggregate is larger than appropriate for molds or test apparatus. This removes oversize
aggregate while preserving the mortar fraction. Sieving must be done promptly to prevent
moisture loss affecting air content and slump results.
Q9: When sampling from a paving mixer (non-agitating equipment), the composite sample
must consist of at least:
A. One portion from the beginning of discharge
B. Two portions from the middle of discharge only
C. Three portions taken at regularly spaced intervals during discharge [CORRECT]
D. Five portions taken randomly
, Correct Answer: C
Rationale: ASTM C172 Para (4.2.3) requires at least three portions taken at regularly spaced
intervals during discharge from non-agitating equipment. Paving mixers have greater
segregation potential; multiple portions ensure representative sampling across the entire
batch discharge sequence.
Q10: Protection of concrete samples from environmental conditions includes all EXCEPT:
A. Protection from direct sunlight
B. Protection from wind causing rapid evaporation
C. Protection from contamination by foreign materials
D. Protection from carbonation by covering with wet burlap only [CORRECT]
Correct Answer: D
Rationale: ASTM C172 Para (4.1) requires protection from sun, wind, contamination, and rapid
evaporation. While wet burlap provides moisture retention, it does not protect against
carbonation (which requires impermeable covers). The standard emphasizes environmental
protection during the critical 15-minute sampling window, not carbonation prevention during
initial curing.
Q11: The composite sample for a single set of strength specimens must be obtained from:
A. Different batches mixed on the same day
B. A single batch of concrete [CORRECT]
C. Multiple trucks if they arrive within 5 minutes
D. Any concrete with the same mix design
Correct Answer: B
Rationale: ASTM C172 Para (4.1) defines the composite sample as representative of a single
batch. Each batch requires its own composite sample for testing. Combining concrete from
different batches, even with identical mix designs, creates an unrepresentative sample that
invalidates test results and quality control data.
Q12: When sampling from a truck mixer, the discharge must be running at the:
A. Slowest possible speed
B. Normal operating speed [CORRECT]
C. Maximum possible speed
D. Intermittent stop-start pattern
Correct Answer: B
