ACI CONCRETE FIELD-TESTING TECHNICIAN GRADE
1: 2026/2027 UPDATED EXAM Q&A - Certified Grade 1
Technician Practice Assessment with Graded A+
Rationales
SECTION 1: SAMPLING & SLUMP (ASTM C172 / C143) — 8 Items
Q1: A field technician arrives at the jobsite and the concrete truck has just discharged
approximately 1.5 ft³ of material. According to ASTM C172, what is the technician's
NEXT action?
A. Obtain the sample immediately from the moving stream at mid-truck
B. Reject this load and wait for the next truck
C. Allow the truck to discharge 1/4 to 1/2 yd³ more before sampling
D. Take the sample from the top of the concrete in the wheelbarrow
Correct Answer: C
Rationale: ASTM C172 requires that samples be obtained from the middle portion of the
load, not the beginning or end. Discharging ~1.5 ft³ is insufficient; the technician must
allow 1/4 to 1/3 yd³ (commonly rounded to 1/4 to 1/2 yd³ in practice) to discharge
before collecting the composite sample.
❌ A: Sampling mid-stream is correct, but NOT at the very start of discharge.
,❌ B: Rejection is not required; the load is acceptable once sufficient material has
passed.
❌ D: Sampling from the top of static concrete violates C172 and risks segregated
material.
Q2: A technician performs a slump test on concrete with a nominal maximum
aggregate size (NMAS) of 1.5 inches. Per ASTM C143, which slump cone configuration
is REQUIRED?
A. Standard 12-inch cone only, regardless of aggregate size
B. Large slump cone with 8-inch diameter base
C. Standard cone, but wet-sieving concrete over 1-inch sieve first
D. Standard cone is acceptable; no wet-sieving required for this NMAS
Correct Answer: D
Rationale: ASTM C143 permits the standard slump cone for aggregates up to 1.5 inches
NMAS. Wet-sieving is only required when NMAS exceeds 1.5 inches (Option C would be
correct for 2-inch NMAS).
❌ A: While the standard cone is used, the "regardless" statement is dangerous for
larger aggregates.
❌ B: No "large slump cone" exists in ASTM C143; this is a fabricated distractor.
❌ C: Wet-sieving is NOT required for 1.5-inch NMAS; this applies to aggregates >1.5
inches.
,Q3: During a slump test, the concrete shears off laterally on one side of the cone. The
technician measures a slump of 3.5 inches on the intact side. Per ASTM C143, what is
the REPORTED slump?
A. 3.5 inches—record the measurement from the intact side
B. Zero slump—shear indicates non-workable concrete
C. Record the test as "shear slump" with zero numerical value
D. Discard the result and perform a new test on a fresh portion
Correct Answer: D
Rationale: ASTM C143 Section 7.3 states that if a shear slump occurs (where the
concrete shears off), the test must be repeated using a fresh portion of the sample. A
shear slump indicates the concrete lacks cohesion for valid measurement.
❌ A: Measuring only the intact side violates standard procedure.
❌ B: Zero slump is incorrect; shear slump is not the same as zero slump (true zero
slump is valid).
❌ C: ASTM C143 does not permit reporting shear slump as a numerical value.
Q4: According to ASTM C172, when sampling from a revolving drum truck mixer, the
minimum number of portions required to form a composite sample is:
A. One continuous sample from the middle third of discharge
B. Two portions, one from the beginning and one from the end
C. Two or more portions taken at regularly spaced intervals during discharge
, D. Three portions: at 1/4, 1/2, and 3/4 points of the load
Correct Answer: C
Rationale: ASTM C172 requires two or more portions taken at regularly spaced intervals
during the discharge of the middle portion of the load to form a representative
composite sample.
❌ A: One portion is insufficient for composite representation.
❌ B: Beginning and end portions are specifically excluded from the composite.
❌ D: While three portions are acceptable, ASTM does not mandate specific fractional
points.
Q5: A technician completes a slump test and observes the concrete retains the mold
shape with no measurable subsidence. Per ASTM C143, this is classified as:
A. Zero slump—valid result if no shear occurred
B. Collapse slump—indicates extremely high workability
C. False slump—test must be repeated with vibration
D. Non-conforming concrete—reject the load immediately
Correct Answer: A
Rationale: A true zero slump (no measurable subsidence) is a valid result under ASTM
C143, provided no shear occurred. This indicates very stiff, low-workability concrete
(common in roller-compacted or paving mixes).
1: 2026/2027 UPDATED EXAM Q&A - Certified Grade 1
Technician Practice Assessment with Graded A+
Rationales
SECTION 1: SAMPLING & SLUMP (ASTM C172 / C143) — 8 Items
Q1: A field technician arrives at the jobsite and the concrete truck has just discharged
approximately 1.5 ft³ of material. According to ASTM C172, what is the technician's
NEXT action?
A. Obtain the sample immediately from the moving stream at mid-truck
B. Reject this load and wait for the next truck
C. Allow the truck to discharge 1/4 to 1/2 yd³ more before sampling
D. Take the sample from the top of the concrete in the wheelbarrow
Correct Answer: C
Rationale: ASTM C172 requires that samples be obtained from the middle portion of the
load, not the beginning or end. Discharging ~1.5 ft³ is insufficient; the technician must
allow 1/4 to 1/3 yd³ (commonly rounded to 1/4 to 1/2 yd³ in practice) to discharge
before collecting the composite sample.
❌ A: Sampling mid-stream is correct, but NOT at the very start of discharge.
,❌ B: Rejection is not required; the load is acceptable once sufficient material has
passed.
❌ D: Sampling from the top of static concrete violates C172 and risks segregated
material.
Q2: A technician performs a slump test on concrete with a nominal maximum
aggregate size (NMAS) of 1.5 inches. Per ASTM C143, which slump cone configuration
is REQUIRED?
A. Standard 12-inch cone only, regardless of aggregate size
B. Large slump cone with 8-inch diameter base
C. Standard cone, but wet-sieving concrete over 1-inch sieve first
D. Standard cone is acceptable; no wet-sieving required for this NMAS
Correct Answer: D
Rationale: ASTM C143 permits the standard slump cone for aggregates up to 1.5 inches
NMAS. Wet-sieving is only required when NMAS exceeds 1.5 inches (Option C would be
correct for 2-inch NMAS).
❌ A: While the standard cone is used, the "regardless" statement is dangerous for
larger aggregates.
❌ B: No "large slump cone" exists in ASTM C143; this is a fabricated distractor.
❌ C: Wet-sieving is NOT required for 1.5-inch NMAS; this applies to aggregates >1.5
inches.
,Q3: During a slump test, the concrete shears off laterally on one side of the cone. The
technician measures a slump of 3.5 inches on the intact side. Per ASTM C143, what is
the REPORTED slump?
A. 3.5 inches—record the measurement from the intact side
B. Zero slump—shear indicates non-workable concrete
C. Record the test as "shear slump" with zero numerical value
D. Discard the result and perform a new test on a fresh portion
Correct Answer: D
Rationale: ASTM C143 Section 7.3 states that if a shear slump occurs (where the
concrete shears off), the test must be repeated using a fresh portion of the sample. A
shear slump indicates the concrete lacks cohesion for valid measurement.
❌ A: Measuring only the intact side violates standard procedure.
❌ B: Zero slump is incorrect; shear slump is not the same as zero slump (true zero
slump is valid).
❌ C: ASTM C143 does not permit reporting shear slump as a numerical value.
Q4: According to ASTM C172, when sampling from a revolving drum truck mixer, the
minimum number of portions required to form a composite sample is:
A. One continuous sample from the middle third of discharge
B. Two portions, one from the beginning and one from the end
C. Two or more portions taken at regularly spaced intervals during discharge
, D. Three portions: at 1/4, 1/2, and 3/4 points of the load
Correct Answer: C
Rationale: ASTM C172 requires two or more portions taken at regularly spaced intervals
during the discharge of the middle portion of the load to form a representative
composite sample.
❌ A: One portion is insufficient for composite representation.
❌ B: Beginning and end portions are specifically excluded from the composite.
❌ D: While three portions are acceptable, ASTM does not mandate specific fractional
points.
Q5: A technician completes a slump test and observes the concrete retains the mold
shape with no measurable subsidence. Per ASTM C143, this is classified as:
A. Zero slump—valid result if no shear occurred
B. Collapse slump—indicates extremely high workability
C. False slump—test must be repeated with vibration
D. Non-conforming concrete—reject the load immediately
Correct Answer: A
Rationale: A true zero slump (no measurable subsidence) is a valid result under ASTM
C143, provided no shear occurred. This indicates very stiff, low-workability concrete
(common in roller-compacted or paving mixes).
