ACI Concrete Field-Testing Technician Grade I | 2026/2027
OBJECTIVE ASSESSMENT - EXAM
ACI Concrete Field-Testing Technician Grade I Certification
Exam (Latest Update 2026/2027) Questions & Answers |
Grade A | 100% Correct 2026/2027
Professional Certification Examination
A+ Verified Grade A
Edition: 2026/2027 100% Correct Answers
Passing Score: 75% Five Content Sections
COVER PAGE - 1
,SECTIONS COVERED
Section 1: Sampling Fresh Concrete (ASTM C172) (Questions 1-10)
Section 2: Slump of Hydraulic-Cement Concrete (ASTM C143) (Questions 11-20)
Section 3: Air Content of Freshly Mixed Concrete (ASTM C231 / C173) (Questions 21-30)
Section 4: Density (Unit Weight), Yield, and Temperature (ASTM C138 / C1064) (Questions 31-40)
Section 5: Making and Curing Specimens & Reporting (ASTM C31 / Standards) (Questions 41-50)
EXAMINATION INFORMATION
This examination evaluates knowledge and application of ASTM standards for field testing of freshly mixed concrete as required
for ACI Concrete Field-Testing Technician Grade I certification. Topics include sampling, slump, air content, density, temperature,
specimen fabrication, and reporting. Each question is worth 1 mark. Passing score is 75%.
Section 1: Sampling Fresh Concrete (ASTM C172)
A concrete delivery arrives at a high-rise project and the technician must obtain a composite sample for acceptance
Q1
testing. The truck has been mixing for 45 minutes and the first portion of concrete is being discharged. According to
ASTM C172, what is the minimum number of portions required to form a composite sample from a revolving-drum
truck mixer and when should sampling begin?
A. Two portions taken after at least 10% and before 90% of the load has been discharged.
B. Three portions taken after the first 0.25 m³ has been discharged and before the last 0.25 m³.
C. Four portions taken at equal intervals throughout the entire discharge of the load.
D. One large portion taken from the middle third of the load only.
Correct Answer: A
Rationale:
ASTM C172 requires a composite sample of at least two portions taken at regularly spaced intervals during discharge of the middle portion of
the batch. Sampling must begin after at least 10% of the load has been discharged and be completed before 90% has been discharged.
Taking only one portion or sampling the very first or last concrete does not produce a representative composite sample.
During sampling of concrete from a paving mixer, the technician observes that the concrete is being discharged in a
Q2
continuous ribbon. The project specifications require a sample for air content and slump. What is the correct sampling
procedure for a paving mixer according to ASTM C172?
A. Obtain the entire sample from one location near the center of the discharge stream.
B. Collect five or more portions from different points across the pile after the mixer has discharged the entire batch.
C. Take two portions from the middle of the batch while the mixer is still discharging.
D. Scoop concrete only from the top surface of the discharged pile to avoid contamination.
Correct Answer: B
Rationale:
For paving mixers, ASTM C172 requires the sample to be obtained by collecting five or more portions from different points in the pile after the
entire batch has been discharged. This differs from truck-mixer sampling because the paving mixer produces a single continuous discharge.
Sampling only the top or middle during discharge does not ensure representativeness.
ACI Concrete Field-Testing Technician Grade I Certification Exam 2026/2027 Page 2
, A technician is preparing to sample concrete that contains 37.5 mm maximum-size aggregate. The sample will be
Q3
used for both slump and air-content tests. What is the minimum size of the composite sample required by ASTM
C172 for this aggregate size when both tests will be performed?
A. 14 L (0.5 ft³)
B. 28 L (1 ft³)
C. 21 L (0.75 ft³)
D. 7 L (0.25 ft³)
Correct Answer: A
Rationale:
ASTM C172 specifies a minimum composite sample size of 14 L (0.5 ft³) when the concrete contains aggregate larger than 25 mm and the
sample is intended for strength specimens or multiple tests. For air content and slump alone with smaller aggregate the size may be reduced,
but 14 L is the required minimum for the stated conditions.
Concrete is being placed by pump into a foundation. The technician is directed to sample the concrete at the point of
Q4
placement. The pump hose is approximately 60 m long. According to ASTM C172, where and how should the sample
be obtained?
A. From the truck chute before the concrete enters the pump hopper.
B. From the discharge end of the pump line at the point of placement by collecting two or more portions.
C. From the middle of the pump hopper after the concrete has been agitated for 2 minutes.
D. From any convenient location along the pump line using a sample thief.
Correct Answer: B
Rationale:
When concrete is delivered by pump or conveyor, ASTM C172 requires sampling at the point of placement (discharge end of the line). The
sample must still be a composite of two or more portions. Sampling at the truck does not represent the concrete that actually reaches the forms
after pumping losses or changes.
After collecting a composite sample, the technician notices that the sample contains a large amount of free water that
Q5
has bled to the surface. The time from the start of sampling to the completion of molding of strength specimens must
not exceed 15 minutes. What is the correct action regarding remixing the sample?
A. Do not remix; the free water is part of the original mixture and should remain.
B. Remix the sample thoroughly by shovel or scoop to redistribute the water and aggregate before testing.
C. Decant the free water and discard it before proceeding with any tests.
D. Add dry cement to absorb the free water and then remix.
Correct Answer: B
Rationale:
ASTM C172 requires that the composite sample be remixed thoroughly with a shovel or scoop immediately before conducting any tests or
molding specimens. This redistributes any free water that has bled and ensures the sample remains representative. Discarding water or adding
materials alters the mixture composition.
ACI Concrete Field-Testing Technician Grade I Certification Exam 2026/2027 Page 3
OBJECTIVE ASSESSMENT - EXAM
ACI Concrete Field-Testing Technician Grade I Certification
Exam (Latest Update 2026/2027) Questions & Answers |
Grade A | 100% Correct 2026/2027
Professional Certification Examination
A+ Verified Grade A
Edition: 2026/2027 100% Correct Answers
Passing Score: 75% Five Content Sections
COVER PAGE - 1
,SECTIONS COVERED
Section 1: Sampling Fresh Concrete (ASTM C172) (Questions 1-10)
Section 2: Slump of Hydraulic-Cement Concrete (ASTM C143) (Questions 11-20)
Section 3: Air Content of Freshly Mixed Concrete (ASTM C231 / C173) (Questions 21-30)
Section 4: Density (Unit Weight), Yield, and Temperature (ASTM C138 / C1064) (Questions 31-40)
Section 5: Making and Curing Specimens & Reporting (ASTM C31 / Standards) (Questions 41-50)
EXAMINATION INFORMATION
This examination evaluates knowledge and application of ASTM standards for field testing of freshly mixed concrete as required
for ACI Concrete Field-Testing Technician Grade I certification. Topics include sampling, slump, air content, density, temperature,
specimen fabrication, and reporting. Each question is worth 1 mark. Passing score is 75%.
Section 1: Sampling Fresh Concrete (ASTM C172)
A concrete delivery arrives at a high-rise project and the technician must obtain a composite sample for acceptance
Q1
testing. The truck has been mixing for 45 minutes and the first portion of concrete is being discharged. According to
ASTM C172, what is the minimum number of portions required to form a composite sample from a revolving-drum
truck mixer and when should sampling begin?
A. Two portions taken after at least 10% and before 90% of the load has been discharged.
B. Three portions taken after the first 0.25 m³ has been discharged and before the last 0.25 m³.
C. Four portions taken at equal intervals throughout the entire discharge of the load.
D. One large portion taken from the middle third of the load only.
Correct Answer: A
Rationale:
ASTM C172 requires a composite sample of at least two portions taken at regularly spaced intervals during discharge of the middle portion of
the batch. Sampling must begin after at least 10% of the load has been discharged and be completed before 90% has been discharged.
Taking only one portion or sampling the very first or last concrete does not produce a representative composite sample.
During sampling of concrete from a paving mixer, the technician observes that the concrete is being discharged in a
Q2
continuous ribbon. The project specifications require a sample for air content and slump. What is the correct sampling
procedure for a paving mixer according to ASTM C172?
A. Obtain the entire sample from one location near the center of the discharge stream.
B. Collect five or more portions from different points across the pile after the mixer has discharged the entire batch.
C. Take two portions from the middle of the batch while the mixer is still discharging.
D. Scoop concrete only from the top surface of the discharged pile to avoid contamination.
Correct Answer: B
Rationale:
For paving mixers, ASTM C172 requires the sample to be obtained by collecting five or more portions from different points in the pile after the
entire batch has been discharged. This differs from truck-mixer sampling because the paving mixer produces a single continuous discharge.
Sampling only the top or middle during discharge does not ensure representativeness.
ACI Concrete Field-Testing Technician Grade I Certification Exam 2026/2027 Page 2
, A technician is preparing to sample concrete that contains 37.5 mm maximum-size aggregate. The sample will be
Q3
used for both slump and air-content tests. What is the minimum size of the composite sample required by ASTM
C172 for this aggregate size when both tests will be performed?
A. 14 L (0.5 ft³)
B. 28 L (1 ft³)
C. 21 L (0.75 ft³)
D. 7 L (0.25 ft³)
Correct Answer: A
Rationale:
ASTM C172 specifies a minimum composite sample size of 14 L (0.5 ft³) when the concrete contains aggregate larger than 25 mm and the
sample is intended for strength specimens or multiple tests. For air content and slump alone with smaller aggregate the size may be reduced,
but 14 L is the required minimum for the stated conditions.
Concrete is being placed by pump into a foundation. The technician is directed to sample the concrete at the point of
Q4
placement. The pump hose is approximately 60 m long. According to ASTM C172, where and how should the sample
be obtained?
A. From the truck chute before the concrete enters the pump hopper.
B. From the discharge end of the pump line at the point of placement by collecting two or more portions.
C. From the middle of the pump hopper after the concrete has been agitated for 2 minutes.
D. From any convenient location along the pump line using a sample thief.
Correct Answer: B
Rationale:
When concrete is delivered by pump or conveyor, ASTM C172 requires sampling at the point of placement (discharge end of the line). The
sample must still be a composite of two or more portions. Sampling at the truck does not represent the concrete that actually reaches the forms
after pumping losses or changes.
After collecting a composite sample, the technician notices that the sample contains a large amount of free water that
Q5
has bled to the surface. The time from the start of sampling to the completion of molding of strength specimens must
not exceed 15 minutes. What is the correct action regarding remixing the sample?
A. Do not remix; the free water is part of the original mixture and should remain.
B. Remix the sample thoroughly by shovel or scoop to redistribute the water and aggregate before testing.
C. Decant the free water and discard it before proceeding with any tests.
D. Add dry cement to absorb the free water and then remix.
Correct Answer: B
Rationale:
ASTM C172 requires that the composite sample be remixed thoroughly with a shovel or scoop immediately before conducting any tests or
molding specimens. This redistributes any free water that has bled and ensures the sample remains representative. Discarding water or adding
materials alters the mixture composition.
ACI Concrete Field-Testing Technician Grade I Certification Exam 2026/2027 Page 3
