ACI Concrete Field Testing Technician Grade I Exam 2026 | Verified Questions & Answers with Detailed Solutions

ACI Concrete Field Testing Technician Grade I
Exam 2026 | Verified Questions & Answers
with Detailed Solutions
ACI CONCRETE FIELD TESTING TECHNICIAN — GRADE I EXAM 2026
Verified Questions & Answers with Detailed Solutions | 300 Questions

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Q1. According to ASTM C172, what is the minimum number of grab samples required to
make a composite sample of freshly mixed concrete?
A) One large sample taken from the middle of the load

B) At least two grab samples taken from different portions of the load

C) At least three grab samples taken from different portions of the load

D) Four samples taken from each corner of the truck

E) Five samples combined from different batches

CORRECT ANSWER: C) At least three grab samples taken from different
portions of the load

RATIONALE: ASTM C172 requires a composite sample to consist of a minimum
of two grab samples (though in practice three or more portions from different parts of
the discharge are used). The standard specifies that the sample shall be obtained by
combining and remixing at least two portions taken at regularly spaced intervals during
discharge of the middle portion of the batch.
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Q2. According to ASTM C172, sampling of freshly mixed concrete should NOT be done
from which portion of the truck discharge?

A) The middle portion of the batch
B) The second quarter of the batch discharge

C) The very first and very last portions of the batch discharge

D) Any portion after 30 minutes of mixing

E) Any portion collected in a wheelbarrow

, CORRECT ANSWER: C) The very first and very last portions of the batch
discharge

RATIONALE: ASTM C172 states that the sample shall not be taken from the very
first or very last portion of the batch discharge. These portions may not be
representative of the total batch due to variations in water content and mixture
uniformity at the beginning and end of the pour.

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Q3. What is the maximum time allowed between obtaining the first and last portions of a
composite concrete sample per ASTM C172?

A) 5 minutes

B) 10 minutes
C) 15 minutes

D) 20 minutes

E) 30 minutes

CORRECT ANSWER: C) 15 minutes

RATIONALE: ASTM C172 requires that the time between obtaining the first and
final portions of the composite sample shall not exceed 15 minutes. This ensures that
the sample is representative of concrete from the same batch without significant change
in workability or hydration.

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Q4. After a composite sample is obtained, all testing and specimen making must begin
within how many minutes per ASTM C172?
A) 5 minutes

B) 10 minutes

C) 20 minutes

D) 30 minutes

E) 45 minutes

CORRECT ANSWER: A) 5 minutes

, RATIONALE: ASTM C172 specifies that testing shall start within 5 minutes after
the composite sample has been obtained. This time limit prevents significant changes in
concrete workability and ensures accurate test results reflecting the concrete's condition
at time of sampling.

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Q5. What is the minimum size of a sampling container used to collect a composite
sample of fresh concrete?

A) 1 gallon (4 L)

B) 3 gallons (11 L)
C) 5 gallons (19 L)

D) 10 gallons (38 L)

E) 15 gallons (57 L)

CORRECT ANSWER: C) 5 gallons (19 L)

RATIONALE: ASTM C172 requires that the sampling container be of sufficient
size to accommodate the entire composite sample. In practice, a minimum 5-gallon
bucket or wheelbarrow is used so that all portions can be combined and remixed to
create a representative composite sample.
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Q6. Before testing, the composite sample of freshly mixed concrete should be:

A) Left undisturbed for 5 minutes to allow settlement

B) Remixed with a shovel to ensure homogeneity

C) Transported directly to the lab without remixing

D) Tested immediately without any additional steps

E) Covered with plastic sheeting and left for 10 minutes

CORRECT ANSWER: B) Remixed with a shovel to ensure homogeneity

RATIONALE: Per ASTM C172, the composite sample shall be remixed with a
shovel to ensure uniformity before testing or making specimens. This step is critical

, because the individual grab samples may have slightly different characteristics that
need to be blended together for a representative sample.

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Q7. Which of the following is NOT an acceptable method of sampling freshly mixed
concrete according to ASTM C172?

A) Collecting samples from a stationary mixer during discharge

B) Collecting samples from a revolving drum truck mixer during discharge

C) Collecting samples from a conveyor belt during placement

D) Collecting a single grab sample from the chute after placement is complete

E) Collecting samples from an open-top truck during discharge

CORRECT ANSWER: D) Collecting a single grab sample from the chute after
placement is complete

RATIONALE: ASTM C172 requires a composite sample made of multiple grab
samples from different portions of the discharge. A single grab sample taken after
placement is complete does not represent the entire batch and does not meet the
standard's requirements for a representative sample.

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Q8. When sampling from a revolving drum mixer truck, where should the samples be
collected from?

A) Directly from the drum before discharge

B) From the discharge chute during the middle portion of the batch

C) From the pump line at the point of delivery

D) From the concrete as placed in the forms

E) From the top layer of the concrete in the drum

CORRECT ANSWER: B) From the discharge chute during the middle portion
of the batch